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Objective: To assess intraocular pressure (IOP) development in cranes and determine the impact of age, weight, species, head position, and sex. Animals Studied: Whooping cranes (WC) (Grus americana), and Mississippi‐sandhill cranes (MSC) (Grus canadensis pulla). Procedures: Chicks were manually restrained on days 1–3, 7, 21, 35, 60, 75, and 120 for routine examinations. IOP was opportunistically measured utilizing the Tonovet Plus® in D setting with the head above the heart (AH) and below the heart (BH). Values were also obtained longitudinally in adults (>120 days old) upon presentation in 1 year. Results: Intraocular pressure was highly correlated with age and weight in chicks. For every kilogram gained, IOP increased 2.46 ± 0.08 mmHg in WC and 2.66 ± 0.11 mmHg in MSC. Once hatched, IOP increased 1.13 ± 0.04 mmHg in WC and 0.87 ± 0.04 mmHg in MSC every 10 days. IOP was similar to adults at 120 days of age. In adult WC, mean IOP AH was 24.0 ± 0.4 mmHg, and BH was 27.9 ± 0.4 mmHg, there was a significant difference regarding head positioning and sex, females (25.3 ± 0.4 mm Hg) had lower IOP than males (26.5 ± 0.4 mmHg). In adult MSC, mean IOP AH was 20.7 ± 0.4 mmHg, and BH was 24.6 ± 0.4 mmHg. The difference between head positioning was significant. Conclusions: This study documents the correlation between IOP and weight or age during early development in cranes, as well as the importance of head positioning. [ABSTRACT FROM AUTHOR]

Wildlife species confront threats from climate and land use change, exacerbating the influence of extreme climatic events on populations and biodiversity. Migratory waterbirds are especially vulnerable to hydrological drought via reduced availability of surface water habitats. We assessed how whooping cranes (Grus americana) modified habitat use and migration strategies during drought to evaluate their resilience to changing conditions and adaptive capacity. We categorized >8000 night‐roost sites used by 146 cranes from 2010 to 2022 and examined relative use during non‐drought, moderate drought, and extreme drought conditions. We found cultivated and uncultivated palustrine and lacustrine wetlands were generally used less during droughts than non‐drought conditions. Conversely, impounded palustrine and lacustrine systems and rivers served more frequently as drought refugia (i.e., used more during drought than non‐drought conditions). Night roosts occurred primarily on private lands (86% overall); public land use decreased with latitude and increased with drought severity, with greatest use (56%) occurring during severe autumn drought in the southern Great Plains. Quantifying use of identified critical habitats in the United States indicated that Cheyenne Bottoms State Waterfowl Management Area and Quivira National Wildlife Refuge were used less during drought, and the Central Platte River and Salt Plains National Wildlife Refuge received similar use during drought compared to non‐drought conditions. Our findings provide insights into compensatory use of habitats, where impounded surface water may function in a complementary fashion with natural wetlands. Collectively, these and other types of wetlands distributed across the migration corridor provided a reliable network of habitat available across the Great Plains. A diversity of wetlands available during variable environmental conditions would be useful in supporting continued recovery of whooping cranes and likely have benefits for a wide array of migratory birds. [ABSTRACT FROM AUTHOR]

Abstract Wildlife species confront threats from climate and land use change, exacerbating the influence of extreme climatic events on populations and biodiversity. Migratory waterbirds are especially vulnerable to hydrological drought via reduced availability of surface water habitats. We assessed how whooping cranes (Grus americana) modified habitat use and migration strategies during drought to evaluate their resilience to changing conditions and adaptive capacity. We categorized >8000 night‐roost sites used by 146 cranes from 2010 to 2022 and examined relative use during non‐drought, moderate drought, and extreme drought conditions. We found cultivated and uncultivated palustrine and lacustrine wetlands were generally used less during droughts than non‐drought conditions. Conversely, impounded palustrine and lacustrine systems and rivers served more frequently as drought refugia (i.e., used more during drought than non‐drought conditions). Night roosts occurred primarily on private lands (86% overall); public land use decreased with latitude and increased with drought severity, with greatest use (56%) occurring during severe autumn drought in the southern Great Plains. Quantifying use of identified critical habitats in the United States indicated that Cheyenne Bottoms State Waterfowl Management Area and Quivira National Wildlife Refuge were used less during drought, and the Central Platte River and Salt Plains National Wildlife Refuge received similar use during drought compared to non‐drought conditions. Our findings provide insights into compensatory use of habitats, where impounded surface water may function in a complementary fashion with natural wetlands. Collectively, these and other types of wetlands distributed across the migration corridor provided a reliable network of habitat available across the Great Plains. A diversity of wetlands available during variable environmental conditions would be useful in supporting continued recovery of whooping cranes and likely have benefits for a wide array of migratory birds.

Research regarding how birds respond to the installation of cameras at nest sites is limited. We installed cameras at nests of Sandhill Cranes Antigone canadensis (Linnaeus, 1758) and federally endangered Whooping Cranes Grus americanaLinnaeus, 1758 in Juneau County, WI, as part of an ongoing study monitoring the reproductive success of Whooping Cranes in WI. The eastern population of Sandhill Cranes has grown, while Whooping Crane population growth has been slow, prompting the need to monitor the reproductive success of cranes on the refuge. We recorded the flight initiation distance during camera installation, the return time after camera installation, as well as measured the distance at which cameras were placed from each nest. We included temperature at camera deployment, age of nest, mode of access, ordinal date, and year in statistical regression models. We found an apparent difference in the observed flight initiation distances between the two species. Sandhill Cranes allowed researchers to approach their nests closer than Whooping Cranes prior to flushing. The post-disturbance return time was influenced by how far away the cameras were placed from the nest and the ambient temperature during camera deploy. Our study may help inform decisions regarding species response to methods and distance when deploying cameras, especially for endangered or disturbance-sensitive species. [ABSTRACT FROM AUTHOR]

Whooping cranes (Grus americana) are naturally seasonal breeders and rely on wetland habitats throughout the annual cycle. However, captive cranes are commonly housed in dry outdoor pens, which may lack key environmental stimuli that in turn compromise reproduction. Our study sought to first, assess seasonal patterns of reproductive hormones in successful versus non-successful bird pairs and second, determine endocrine responses to alterations in enclosure environments. Fecal samples were collected from eight crane pairs year-round for 3 consecutive years, once a week during non-breeding season and three times a week during the breeding season. During Year 1, all pairs were housed in traditional dry pens, whereas during January of Year 2 all pairs were moved to either new dry pens (control, n = 4) or ponded pens (wetland, n = 4) and remained in the same pen until the end of the study. Fecal samples were assessed for gonadal (year-round) and adrenal (breeding season only) hormones. Estrogen and progestagen metabolite concentrations were low during non-breeding season in all females. However, as birds transition into a breeding season, gonadal hormone concentrations significantly increased (p

Many migratory bird species have begun shifting their wintering grounds closer to their breeding grounds, shortening their yearly migration distance through a behavior called shortstopping. While multiple studies have investigated possible drivers, it remains unclear why only some populations adopt this behavior.We studied the differential occurrence of shortstopping in two populations of Whooping Cranes (Grus americana): a remnant population where juveniles migrate with their parents, and a reintroduced population consisting largely of captive-reared birds trained to migrate by unrelated conspecifics or by humans. Shortstopping is widespread in the reintroduced population, while the remnant population has not shown any appreciable northward movement of its overwintering sites. We examined potential drivers for this lack of shortstopping, including a lack of suitable habitat north of their current wintering area or social differences between populations.Using characteristics of winter locations used by the reintroduced population, we found that 31.4% of the remnant migration corridor was predicted to be suitable for wintering, suggesting that insufficient habitat suitability is not limiting shortstopping behaviour. However, we found evidence for behavioural differences that might explain the absence of shortstopping in the remnant population: while all juveniles of the remnant population associate with their parents during overwintering, juveniles from the reintroduced population did not associate with older conspecifics in 12 out of 25 observed wintering events, suggesting that the social transmission of winter migration behaviours might be less effective in the reintroduced population. Although social learning is generally believed to increase flexibility in migratory strategies, a strong vertical transmission of behaviour might enforce adherence to established traditions and reduce the uptake of novel behaviours such as shortstopping. We suggest that, besides habitat availability, social factors may also play a role in explaining the absence of shortstopping behaviour in some migratory bird populations.

Increases in population size and reductions in suitable migration stopover habitat associated with drought, water development, and agricultural practices, along with conspecific attraction, are hypothesized mechanisms for increasing flock sizes of migrating Whooping Cranes. During autumn 2021, we observed such a phenomenon during a period of drought in the central Great Plains when 46 Whooping Cranes gathered as a single flock in the central Platte River valley. We provide a detailed account of how this larger aggregation formed from 5 smaller groups, behavioral observations, and environmental conditions experienced during this event including river flow, ambient temperature, and wind and drought conditions. Here, we report considerations for environmental and hydrologic conditions preceding and during this event as well as use patterns and behaviors we observed while the largest single flock of Whooping Cranes ever documented in the United States portion of the migration corridor was in the central Platte River valley. [ABSTRACT FROM AUTHOR]

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Abstract Natal dispersal is a key demographic process for evaluating the population rate of change, especially for long‐lived, highly mobile species. This process is largely unknown for reintroduced populations of endangered avian species. We evaluated natal dispersal distances (NDD) for male and female Whooping Cranes (Grus americana) introduced into two locations in central Wisconsin (Necedah National Wildlife Refuge, or NNWR, and the Eastern Rectangle, or ER) using a series of demographic, spatial, and life history‐related covariates. Data were analyzed using gamma regression models with a log‐link function and compared using Akaike information criterion corrected for small sample sizes (AICc). Whooping Cranes released in the ER dispersed 261% further than those released into NNWR, dispersal distance increased 4% for each additional nesting pair, decreased about 24% for males as compared to females, increased by 21% for inexperienced pairs, and decreased by 3% for each additional year of age. Natal philopatry, habitat availability or suitability, and competition for breeding territories may be influencing observed patterns of NDD. Whooping Cranes released in the ER may exhibit longer NDD due to fragmented habitat or conspecific attraction to established breeding pairs at NNWR. Additionally, sex‐biased dispersal may be increasing in this population as there are more individuals from different natal sites forming breeding pairs. As the population grows and continues to disperse, the drivers of NDD patterns may change based on individual or population behavior.

Captive breeding is an increasingly used conservation strategy for species with a high risk of extinction in the wild, but managing a captive breeding programme can be challenging if there is a deficiency in knowledge about the species' breeding biology. A knowledge gap can make it difficult to evaluate different management options. For avian species, egg hatching success is a key demographic parameter, and data‐logging egg technology can provide important information on optimal species‐specific incubation conditions, which can help inform captive breeding practises and identify efficient captive management options. In the context of a captive breeding programme for endangered Whooping Cranes Grus americana, we investigated associations between hatching success and incubation conditions, including environmental parameters (temperature, relative humidity and egg turning rate), and incubation type (artificial incubation; foster incubation by Sandhill Cranes, Grus canadensis; and Whooping Crane incubation). Finally, we considered both cost and breeding output in an analysis of incubation practises. We found that daily mean temperatures were negatively associated with hatching success, and that hatching success was highest with incubation under Sandhill Cranes. However, incubation by artificial incubators, rather than Sandhill Cranes, provided a trade‐off between cost and breeding output that is likely to be acceptable to many captive programme managers. We encourage other captive breeding programmes to use innovations that help to increase potential release numbers for conservation translocations by considering biological and financial constraints. [ABSTRACT FROM AUTHOR]

We investigated concentrations of blood total mercury (THg) in three extant populations of endangered Whooping Crane (Grus americana). Blood THg was greater in cranes reintroduced during 2001–2008 that range in the eastern US (median = 0.31 ug/g ww) than both wild cranes in central North America (median = 0.11 ug/g ww) and from captivity (median = 0.01 ug/g ww). The median THg blood concentrations in the two free-ranging populations of Whooping Cranes were low compared to reproductive toxic thresholds suggested for other large bird species (> 4.3 ug/g ww), but a singular elevated concentration was observed in one crane (1.04 ug/g ww; 6% of samples from the reintroduced population). These results likely reflect variable dietary Hg exposure among these populations, but should prompt additional biomonitoring to discern risk of greater Hg exposure nearer to the time of breeding and potential effects on productivity. [ABSTRACT FROM AUTHOR]

A portion of the Aransas-Wood Buffalo population of Whooping Cranes (Grus americana) stopover within the Central Platte River Valley (CPRV) annually. Past studies have found Whooping Cranes select herbaceous wetlands over agricultural fields when evaluated at a migration-corridor scale. However, recent studies conducted within the CPRV have reported Whooping Cranes selected agricultural fields and avoided herbaceous landcover classes. We hypothesized that much of this discrepancy was due to differences in landcover classifications used in previous studies, particularly those related to wetland designations. We used multiple existing, fine-scale geospatial data sources considering both landcover and hydrological factors to define unique and regionally specific ecotopes, which are the smallest homogenous and biologically relevant mappable units of analysis in landscape ecology (e.g., meadow-marsh, upland agriculture, etc.). We examined whether ecotope-based landcover, when evaluated at multiple spatial scales (i.e., 400 m and 1000 m), predicted terrestrial Whooping Crane occurrence within the CPRV. We used generalized linear mixed models within an information-theoretic approach to assess Whooping Crane occurrence within the CPRV. We found distinct ecotopes at the 1000-m scale explained nearly 40% of the variation in Whooping Crane occurrence. Ecotope models outperformed models including only their component parts such as flooding frequency and wetland designation. Whooping Cranes occurred more frequently within wetland portions of both agricultural fields and natural herbaceous communities and were less likely to use analogous upland components. We also found that occurrence was positively associated with proximity to the main channel of the Platte River and that Whooping Cranes avoided roads and developed areas, as several other studies have reported. Our findings indicate herbaceous and agricultural wetland areas should be targeted for Whooping Crane conservation efforts within the CPRV and perhaps regionally.

Natal dispersal is a key demographic process for evaluating the population rate of change, especially for long‐lived, highly mobile species. This process is largely unknown for reintroduced populations of endangered avian species. We evaluated natal dispersal distances (NDD) for male and female Whooping Cranes (Grus americana) introduced into two locations in central Wisconsin (Necedah National Wildlife Refuge, or NNWR, and the Eastern Rectangle, or ER) using a series of demographic, spatial, and life history‐related covariates. Data were analyzed using gamma regression models with a log‐link function and compared using Akaike information criterion corrected for small sample sizes (AICc). Whooping Cranes released in the ER dispersed 261% further than those released into NNWR, dispersal distance increased 4% for each additional nesting pair, decreased about 24% for males as compared to females, increased by 21% for inexperienced pairs, and decreased by 3% for each additional year of age. Natal philopatry, habitat availability or suitability, and competition for breeding territories may be influencing observed patterns of NDD. Whooping Cranes released in the ER may exhibit longer NDD due to fragmented habitat or conspecific attraction to established breeding pairs at NNWR. Additionally, sex‐biased dispersal may be increasing in this population as there are more individuals from different natal sites forming breeding pairs. As the population grows and continues to disperse, the drivers of NDD patterns may change based on individual or population behavior. [ABSTRACT FROM AUTHOR]

Electricity generation from renewable‐energy sources has increased dramatically worldwide in recent decades. Risks associated with wind‐energy infrastructure are not well understood for endangered Whooping Cranes (Grus americana) or other vulnerable Crane populations. From 2010 to 2016, we monitored 57 Whooping Cranes with remote‐telemetry devices in the United States Great Plains to determine potential changes in migration distribution (i.e., avoidance) caused by presence of wind‐energy infrastructure. During our study, the number of wind towers tripled in the Whooping Crane migration corridor and quadrupled in the corridor's center. Median distance of Whooping Crane locations from nearest wind tower was 52.1 km, and 99% of locations were >4.3 km from wind towers. A habitat selection analysis revealed that Whooping Cranes used areas ≤5.0 km (95% confidence interval [CI] 4.8–5.4) from towers less than expected (i.e., zone of influence) and that Whooping Cranes were 20 times (95% CI 14–64) more likely to use areas outside compared to adjacent to towers. Eighty percent of Whooping Crane locations and 20% of wind towers were located in areas with the highest relative probability of Whooping Crane use based on our model, which comprised 20% of the study area. Whooping Cranes selected for these places, whereas developers constructed wind infrastructure at random relative to desirable Whooping Crane habitat. As of early 2020, 4.6% of the study area and 5.0% of the highest‐selected Whooping Crane habitat were within the collective zone of influence. The affected area equates to habitat loss ascribed to wind‐energy infrastructure; losses from other disturbances have not been quantified. Continued growth of the Whooping Crane population during this period of wind infrastructure construction suggests no immediate population‐level consequences. Chronic or lag effects of habitat loss are unknown but possible for long‐lived species. Preferentially constructing future wind infrastructure outside of the migration corridor or inside of the corridor at sites with low probability of Whooping Crane use would allow for continued wind‐energy development in the Great Plains with minimal additional risk to highly selected habitat that supports recovery of this endangered species. [ABSTRACT FROM AUTHOR]

Effective outreach for an endangered species often requires an understanding of human dimensions information to guide pro-conservation behavior. To provide a foundation for outreach communication strategies regarding Whooping Crane conservation in Alabama, we administered surveys to local residents, waterfowl hunters, and birders. We tested a theoretical framework using constructs from the cognitive hierarchy, value-belief-norm theory, emotional dispositions, and knowledge about the species to identify the best predictors of attitudes and behavioral intentions toward the conservation of Whooping Cranes. Regression analyzes revealed that a combination of constructs from these frameworks directly predicted attitudes and behavioral intentions toward Whooping Cranes. Findings demonstrated that the best predictors were different across audiences and different for predicting attitudes and behavioral intentions. Each of the predictor variables from the multiple theories provided explanatory power for both attitudes and behavioral intentions and across all audiences. Outreach can use this information to develop content and audience-specific messaging. [ABSTRACT FROM AUTHOR]

Recent detections of large gatherings of Whooping Cranes suggest that flock sizes may be increasing at some stopover locations during both the spring and fall migrations. We used the public sightings database managed by the US Fish and Wildlife Service from 1942 to 2018 to analyze data for long-term trends in group size. We then examined the spatial distribution of large groups to explore potential explanations for these occurrences. The proportion of Whooping Crane groups comprised of 2, 3, and 4–6 individuals showed no trend over time. However, observations of individuals showed a declining trend and groups of 7–9 and ≥10 showed an increasing trend. The frequency of groups observed exceeding 5 and 10 individuals were better predicted by survey year than by Whooping Crane population size suggesting that an increasing population is not the sole driver of large group occurrences. Our results indicate that large groups occur disproportionately within the 50% migration corridor, at staging areas within the first or last 20–30% of the migration path, and near conservation-managed wetlands, particularly within the southern Great Plains. Our results suggest that in addition to population growth, conspecific attraction, location within the migration corridor, and habitat loss may be contributing to large group occurrences. Further research is needed to determine the degree to which these factors influence large Whooping Crane group formation. The gathering of large numbers of Whooping Cranes in a single location presents potential tradeoffs for the species. While increasing group sizes may improve threat detection and avoidance, it comes at a cost of increased disease and mass mortality risk.

Accounts of same-sex nesting behaviors have been observed in several wild and captive bird species, but the evolutionary adaptation of this behavior remains unclear. There have been reports of male-male and female-female territorial pairs of Whooping Cranes (Grus americana) in two reintroduced populations. However, this is the first documentation of nesting behavior of a same-sex pair of Whooping Cranes. The incubation rhythm and nesting behaviors of a female-female Whooping Crane pair nesting at McMillan Marsh Wildlife Area in Marathon County, Wisconsin, USA, were documented using a nest camera. The female-female pair displayed comparable nest constancy (99.7%) and incubation behaviors to male-female Whooping Crane pairs in the same population. Both females of the pair incubated the nest; however, the older female incubated for longer periods of time than the younger female (235.8 ± 20.7 min and 168.3 ± 17.2 min, respectively). The pair exchanged incubation duties 5.7 ± 0.2 and 1.1 ± 0.2 times daily during daylight hours and nighttime hours, respectively. The two females incubated the nest for at least 28 days, but fate of the eggs was not determined. Ultimately, the cause of this pairing remains unknown. This behavior could have implications for the breeding success of this small, reintroduced population of Whooping Cranes. [ABSTRACT FROM AUTHOR]

Global biodiversity losses continue despite tremendous growth in the volume of conservation science and many local successes. Research that can achieve conservation science's aims—arresting declines in biodiversity and preventing extinctions—is therefore of ever greater importance. Here, we ask whether conservation science, as currently performed, is progressing in such a way as to maximize its impact. We present a simple framework for how effective conservation research could progress, from identifying problems to diagnosing their proximate and ultimate causes, and from proposing, to designing, implementing, and testing responses. We then demonstrate that for three well‐known examples—South Asian vultures, whooping cranes, and bycatch of procellariform seabirds—published studies appear to follow this sequence, with considerable benefits. However, for a representative sample of the wider conservation literature, we find no evidence of such a progression. Instead, the vast majority of papers remain focused on describing the state of nature or on mechanisms directly causing changes, with very little research on designing or implementing conservation responses. This lack of research on the sorts of questions that might most help conservation science deliver its stated mission strongly suggests we will struggle to translate the huge increase in research activity into real‐world benefits. [ABSTRACT FROM AUTHOR]

We reviewed necropsy records of 124 Whooping Cranes (Grus americana) recovered following reintroduction of 268 individuals from 2001 to 2016 in the eastern US. Causes of death were determined in 62% (77/124) of cases facilitated by active monitoring that limited decomposition and scavenging artifact. The greatest proportions of mortality were caused by predation (0.468; 95% confidence interval 0.356–0.580; 36/77), collision with power lines or vehicles (0.260; 0.162–0.358; 20/77), and gunshot (0.169; 0.085–0.253; 13/77). Six deaths were attributed to infection (0.078; 0.018–0.138; 6/77), including bacterial and fungal etiologies. Lead analysis of 50 liver samples yielded two results with elevated concentrations (3.65 and 10.97 ppm wet weight), and 10 bone samples from partial carcasses lacking suitable liver tissue resulted in one elevated result (48.82 ppm dry weight). These data indicate that underlying subclinical or clinical lead toxicosis may be a factor in up to 5% of deaths attributed to predation or impact trauma. Brain cholinesterase activity testing indicated no exposure to organophosphate or carbamate pesticides (mean±SD=17.32±2.90 µmol/min/g, 31/71). The causes of death and potential underlying factors summarized in this study constitute the first definitive mortality survey of migratory Whooping Cranes based on a high carcass recovery rate. Causes of death by infectious etiologies remained comparatively rare in this study, and occurred as single cases with no evidence of sustained transmission among reintroduced Whooping Cranes. [ABSTRACT FROM AUTHOR]

Migratory birds use numerous strategies to successfully complete twice-annual movements between breeding and wintering sites. Context for conservation and management can be provided by characterizing these strategies. Variations in strategy among and within individuals support population persistence in response to changes in land use and climate. We used location data from 58 marked Whooping Cranes (Grus americana) from 2010 to 2016 to characterize migration strategies in the U.S. Great Plains and Canadian Prairies and southern boreal region, and to explore sources of heterogeneity in their migration strategy, including space use, timing, and performance. Whooping Cranes completed ∼3,900-km migrations that averaged 29 days during spring and 45 days during autumn, while making 11–12 nighttime stops. At the scale of our analysis, individual Whooping Cranes showed little consistency in stopover sites used among migration seasons (i.e. low site fidelity). In contrast, individuals expressed a measure of consistency in timing, especially migration initiation dates. Whooping Cranes migrated at different times based on age and reproductive status, where adults with young initiated autumn migration after other birds, and adults with and without young initiated spring migration before subadult birds. Time spent at stopover sites was positively associated with migration bout length and negatively associated with time spent at previous stopover sites, indicating Whooping Cranes acquired energy resources at some stopover sites that they used to fuel migration. Whooping Cranes were faithful to a defined migration corridor but showed less fidelity in their selection of nighttime stopover sites; hence, spatial targeting of conservation actions may be better informed by associations with landscape and habitat features rather than documented past use at specific locations. The preservation of variation in migration strategies existing within this species that experienced a severe population bottleneck suggests that Whooping Cranes have maintained a capacity to adjust strategies when confronted with future changes in land use and climate. [ABSTRACT FROM AUTHOR]

Biochemical and trace element analyses of blood from wild Whooping Cranes (Grus americana) were performed to assess the health of the only self-sustaining, migratory population in North America. Juvenile cranes (n=31) approximately 49–70 d-old were sampled at Wood Buffalo National Park, Northwest Territories, Canada, in midsummer from 2010 to 2012. Archived serum (n=24) and whole blood (n=31) samples from captive juvenile cranes were selected as age-matched controls. Reference values were calculated for serum biochemical analytes and trace elements in whole blood from the captive juvenile Whooping Cranes reared under controlled conditions and with known health histories. Several statistical differences among blood biochemical and trace element values of the wild and captive juveniles were identified and were likely attributable to dietary differences between the populations. [ABSTRACT FROM AUTHOR]

Juvenile whooping cranes (Grus americana) raised for wild release were found to have an increased incidence of rib fractures at fledging in 2017 compared with the previous 16 years. Serum analysis showed 30-day-old juveniles in 2017 (n = 12) had significantly lower 25-hydroxyvitamin D3 and significantly higher parathyroid hormone concentrations than juveniles in 2010 (n = 6) with no history of rib fractures. Increased serum parathyroid hormone concentrations in the 2017 juveniles persisted to fledging age. Review of dietary and environmental management revealed that juveniles in 2017 were provided a commercial diet with a lower, and perhaps suboptimal, calcium:phosphorus ratio and experienced reduced time outdoors in the first month after hatch, presumably resulting in less ultraviolet B radiation exposure. Mild hyperparathyroidism in precocial whooping cranes may result when dietary constraints and/or outdoor access is compromised and manifest as rib fractures in the absence of traumatic injury. [ABSTRACT FROM AUTHOR]

The whooping crane (Grus americana) has been managed in captivity since the 1960s following a substantial genetic bottleneck in the wild population. Through major ex situ conservation efforts, there are 158 whooping cranes managed in North American institutions and chicks are released annually into the wild. Current reintroduction goals for the whooping crane however, are impeded by poor reproduction within the ex situ population, in part because of low egg fertility. Development of improved management techniques to overcome low egg fertility requires a better understanding of factors that influence egg fertility. We collected data for eggs laid at Patuxent Wildlife Research Center from 2005–2014 (n = 438 eggs; n = 23 pairs). We constructed 5 sets of generalized linear mixed‐models, with a Bernoulli‐distributed response variable (fertile or infertile), to address the effects of egg‐specific variables (month laid, sequence, and clutch order of the egg), life‐history events of the male and female (age, rearing method, wing condition, age at first pairing, age at current pairing, and female age at first laying), pair‐specific characteristics (kinship, years paired, chick‐rearing experience, and previous pairings), and captive management decisions (inclusion in the artificial insemination program and pair experience chick‐rearing) on the probability of egg fertility. Our results indicate that female‐specific factors (especially age, age at current pairing, and wing status) and pair‐specific factors of kinship, chick‐rearing experience, copulation, and inclusion in the artificial insemination program influenced fertile egg production. Specifically, the younger a female is when paired with her current social mate, the higher probability that her eggs will be fertile. Furthermore, high kinship reduced fertility, whereas chick‐rearing experience and artificial insemination of females with a donor male other than her social mate increased fertility. Further research on mate selection and reproductive mechanisms is needed to better understand egg laying and egg fertility in the whooping crane. © 2019 The Wildlife Society. Our results recommend providing opportunities for captive birds to engage in natural breeding behaviors including allowing pairs to raise chicks, allowing individuals to retain full use of their wings, and forming sexually compatible pairs early in the female's life to maximize reproductive potential of captively managed whooping cranes. [ABSTRACT FROM AUTHOR]

Migratory birds like endangered whooping cranes (Grus americana) require suitable nocturnal roost sites during twice annual migrations. Whooping cranes primarily roost in shallow surface water wetlands, ponds, and rivers. All these features have been greatly impacted by human activities, which present threats to the continued recovery of the species. A portion of one such river, the central Platte River, has been identified as critical habitat for the survival of the endangered whooping crane. Management intervention is now underway to rehabilitate habitat form and function on the central Platte River to increase use and thereby contribute to the survival of whooping cranes. The goal of our analyses was to develop habitat selection models that could be used to direct riverine habitat management activities (i.e., channel widening, tree removal, flow augmentation, etc.) along the central Platte River and throughout the species’ range. As such, we focused our analyses on two robust sets of whooping crane observations and habitat metrics the Platte River Recovery Implementation Program (Program or PRRIP) and other such organizations could influence. This included channel characteristics such as total channel width, the width of channel unobstructed by dense vegetation, and distance of forest from the edge of the channel and flow-related metrics like wetted width and unit discharge (flow volume per linear meter of wetted channel width) that could be influenced by flow augmentation or reductions during migration. We used 17 years of systematic monitoring data in a discrete-choice framework to evaluate the influence these various metrics have on the relative probability of whooping crane use and found the width of channel unobstructed by dense vegetation and distance to the nearest forest were the best predictors of whooping crane use. Secondly, we used telemetry data obtained from a sample of 38 birds of all ages over the course of seven years, 2010–2016, to evaluate whooping crane use of riverine habitat within the North-central Great Plains, USA. For this second analysis, we focused on the two metrics found to be important predictors of whooping crane use along the central Platte River, unobstructed channel width and distance to nearest forest or wooded area. Our findings indicate resource managers, such as the Program, have the potential to influence whooping crane use of the central Platte River through removal of in-channel vegetation to increase the unobstructed width of narrow channels and through removal of trees along the bank line to increase unforested corridor widths. Results of both analyses also indicated that increases in relative probability of use by whooping cranes did not appreciably increase with unobstructed views ≥200 m wide and unforested corridor widths that were ≥330 m. Therefore, managing riverine sites for channels widths >200 m and removing trees beyond 165 m from the channel’s edge would increase costs associated with implementing management actions such as channel and bank-line disking, removing trees, augmenting flow, etc. without necessarily realizing an additional appreciable increase in use by migrating whooping cranes. [ABSTRACT FROM AUTHOR]

Stopover sites provide important forage resources and protection from predators to the Aransas-Wood Buffalo population of Whooping Cranes (Grus americana) as they migrate 4000 km across the Great Plains each spring and fall. Given the Whooping Crane's expansive migration corridor, sensitivity to human disturbance, small population size, and protected status under the Endangered Species Act, it is challenging to gather detailed information regarding the particular forage resources that the cranes exploit at various stopover locations. On 22 March 2018 we observed and photo-documented an adult Whooping Crane consuming at least 5 individual juvenile channel catfish (Ictalurus punctatus) after it landed 100 m in front of our Sandhill Crane viewing blind on the south channel of the Platte River. Using the average exposed culmen length of an adult Whooping Crane for reference, we estimated that the length of the channel catfish ranged from 97 mm to 117 mm. Growth estimates developed from the Lower Platte River suggest that the depredated channel catfish were just over one year old. To the best of our knowledge, our observations represent the first definitive record of a Whooping Crane consuming fish in the Platte River, as well as the first record of a Whooping Crane depredating a channel catfish in the Great Plains. Given the relatively long distances at which Whooping Cranes are generally viewed (≥650 m), small-bodied fish may be a more common prey item during migration than indicated by current scientific literature. Our note demonstrates how wildlife photography and ecotourism can contribute to our understanding of species' natural histories. [ABSTRACT FROM AUTHOR]

Twice annually, the last remaining wild and self-sustaining migratory population of Whooping Cranes (Grus americana) migrates through central Nebraska on its approximately 3900-km journey between Aransas National Wildlife Refuge on the Gulf Coast of Texas and Wood Buffalo National Park in Alberta, Canada. On 27 March 2018, a juvenile Bald Eagle (Haliaeetus leucocephalus) was observed attacking a Whooping Crane on the Loup River near Rockville, Nebraska. The encounter, documented by a private landowner, was forwarded to the U.S. Fish and Wildlife Service as part of the decades-long citizen-science effort undertaken to track and record public sightings of Whooping Cranes during migration. Crane species have few avian predators, and observations of depredations upon these crane species are rare. The Whooping Crane fended off the Bald Eagle, utilizing a "jump-rake" defense; neither species appeared harmed by the clearly aggressive interaction. The episode was reflective of recent observations of Bald Eagles depredating Sandhill Cranes on the Platte River during the spring migration. To our knowledge, this is the first description in scientific literature of a Bald Eagle attacking a Whooping Crane from the Aransas-Wood Buffalo population. [ABSTRACT FROM AUTHOR]

Wide channels with short bank vegetation, access to nearby foraging habitat, shallow water areas (<30 cm deep), and absence of disturbance features are factors commonly associated with suitable roost sites for Sandhill Cranes (Antigone canadensis). However, since channel width has typically been evaluated independently of channel depth and flow, it is possible that use of narrow channels is not limited so much by a requirement for wider channels but by deeper water that flows through these narrow channels. We used a discrete-choice modeling framework and 9 years of roost location data to evaluate the influence of channel-width measures and flow per linear unit of channel width on roost-site selection by Sandhill Cranes. Roost-site selection was influenced by maximum unvegetated channel width and flow per unit length of total unvegetated channel width of all channels. The relative selection ratio increased as maximum unvegetated channel width increased to 131 m for small groups (≤500 cranes) and 275 m for large groups (>5000 cranes), but the ratio was statistically similar across a wide range of maximum unobstructed channel widths. Medium-sized Sandhill Crane groups (501–5000 cranes) were less influenced by in-channel vegetated islands, and these groups selected channels based on wide total unvegetated channel widths. Our results also suggest that flows ≤39.05 m3/s (cms; 1379 cfs) in channels that are 275 m in unvegetated width maximize selection ratios for medium and large crane groups, so flows above this level may not improve Sandhill Crane roosting habitat conditions during the spring migration and staging season within the central Platte River. While Sandhill Cranes stage within the central Platte River valley for a longer time interval in the spring, Whooping Cranes (Grus americana) also use the Platte River as a stopover point. Both species share similar indices for roosting habitat, such as unobstructed channel width and shallow water depths. The results of our investigation could be used to identify a range of flows and channel width configurations expected to generate the highest amount of suitable habitat for Sandhill Cranes roosting along the central Platte River. [ABSTRACT FROM AUTHOR]

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Abstract The Mission-Aransas Estuary is the wintering ground for the only sustained wild population of the endangered whooping crane (Grus americana), and blue crabs (Callinectes sapidus) are an important component of their diet as well as being a major food source for important sport fishes such as the red and black drum. Blue crabs also support a commercial crabbing industry, and fisheries data indicate that blue crab populations have been declining since the 1980s. Possible factors leading to decline in blue crab populations include overfishing, increased populations and predation by regulated sport fishes, reduced freshwater inflows into estuaries, and reduced larval recruitment. Little is known about blue crab recruitment dynamics in this region, but restricted passes between coastal estuaries and the Gulf of Mexico along with extended periods of drought that often lead to hypersaline conditions in coastal bays may limit larval recruitment from the Gulf into the bays. To investigate blue crab larval recruitment patterns, citizen scientist volunteers used hogshair settlement collectors to sample five monitoring sites over a four year period. Results show that large numbers of blue crab megalopae are common in nearshore waters of the Gulf of Mexico, but only a small fraction (∼1%) recruit into the estuary. Peak periods of ingress into the estuary occur during fall and winter months, with C. sapidus primarily contributing to the fall peak and C. similis dominating the winter peak. Increased salinity in the estuary during droughts may reduce the ability of blue crab larvae to detect and enter passes into the estuary. Graphical abstract Image 1 Highlights • Small fraction of blue crab larvae in nearshore Gulf of Mexico recruit to estuary. • Seasonal settlement peak of Callinectes sapidus occurs in fall. • Seasonal settlement peak of Callinectes similis occurs in winter. [ABSTRACT FROM AUTHOR]

The capacity to cryopreserve semen from captive cranes facilitates production of offspring from behaviorally incompatible or geographically separated pairs, and allows for long-term preservation of valuable genetic materials. The present study sought to develop effective cryopreservation protocols for whooping ( Grus americana ) and white-naped ( Grus vipio ) cranes, through examining the influences of two permeating (DMA and Me 2 SO) and one non-permeating (sucrose) cryoprotectants, as well as vitamin E on post-thaw sperm survival. In Study 1, ejaculates (whooping: n  = 10, white-naped: n = 8) were collected and cryopreserved in one of six cryo-diluents (crane extender with: DMA; DMA+0.1M sucrose; Me 2 SO; Me 2 SO+0.1M sucrose; 0.1M sucrose; 0.2M sucrose) using a two-step cooling method. Frozen samples were thawed and assessed for overall motility, motion characteristics, membrane integrity, morphology, and ability to bind to the inner perivitelline membrane (IPVM). In Study 2, whooping crane ejaculates ( n  = 17) were frozen in crane extender containing Me 2 SO alone or with vitamin E (5 μg/mL or 10 μg/mL). Frozen samples were thawed and assessed as in Study 1, except the binding assay. White-naped crane sperm were more tolerant to cryopreservation than whooping crane (15% vs 6% post-thawed motility). In both species, sperm cryopreserved in medium containing Me 2 SO alone displayed higher post thaw survival and ability to bind to IPVM than the other cryodiluent treatments. Vitamin E supplementation exerted no benefits to post thaw motility or membrane integrity. The findings demonstrated that there was species specificity in the susceptibility to cryopreservation. Nevertheless, Me 2 SO was a preferred cryoprotectant for sperm from both whooping and white-naped cranes. [ABSTRACT FROM AUTHOR]

A central component of successful wildlife conservation is the understanding of public perceptions toward a species. We administered an online survey to Alabama waterfowl hunters (n = 284) to examine differences in awareness and knowledge of and attitudes toward Whooping Cranes. We investigated if these variables and/or birding specialization influenced likeliness to participate in conservation behaviors. Specialization level was positively related to awareness, knowledge, and conservation attitudes. Respondents with greater knowledge and favorable attitudes toward cranes were more likely to donate to a hypothetical crane conservation fund, and expert birdwatchers were more likely to belong to a birding organization than novice or intermediate birdwatchers. Our research supplements existing birding specialization literature by incorporating cognitive variables specific to Whooping Cranes. Findings suggested that enhancing knowledge regarding Whooping Crane conservation may be an advantageous strategy for promoting conservation and positive behaviors toward the species. [ABSTRACT FROM AUTHOR]

Though an important measure for ecological studies, obtaining foraging data through direct observation is rarely assessed independently. Using field measurements (foraging habitat, food acquisition behavior, and food manipulation time), the summer diet of Whooping Cranes ( Grus americana) in Wisconsin, USA, was determined; foods consumed based on foraging behavior were identified; and ingestion for Sandhill Cranes (Antigone canadensis) was assessed. Based on 102 observations, Whooping Cranes occupying six territories consumed 17 food items (verified with images), of which 90 samples from nine foods were modeled. Food manipulation time predicted food size: ln(y) = 3.50 + 0.45 ln(x) - 0.05 ln(x2) ( r2 = 0.63, P< 0.001). Classification tree analysis identified consumed food using foraging behavior (error rate = 17%). A schematic model with the same three behavioral variables and an additional variable of direct observation identified 93% of 90 items. With Sandhill Cranes, observed swallows predicted actual swallows (y = 1.12x - 6.18 ( r2 = 0.85, 95% CI of slope = 0.79 to 1.45, 95% CI of y-intercept = -50.55 to 38.19)). Field observation of diet and ingestion can be applied to any bird species that uses open habitats where food acquisition behavior and food size vary enough to inform models of foraging behavior. [ABSTRACT FROM AUTHOR]

Defining and identifying changes to seasonal ranges of migratory species is required for effective conservation. Historic sightings of migrating whooping cranes (Grus americana) have served as sole source of information to define a migration corridor in the Great Plains of North America (i.e., Canadian Prairies and United States Great Plains) for this endangered species. We updated this effort using past opportunistic sightings from 1942–2016 (n = 5,055) and more recent (2010–2016) location data from 58 telemetered birds (n = 4,423) to delineate migration corridors that included 50%, 75%, and 95% core areas. All migration corridors were well defined and relatively compact, with the 95% core corridor averaging 294 km wide, although it varied approximately ±40% in width from 170 km in central Texas to 407 km at the international border of the United States and Canada. Based on historic sightings and telemetry locations, we detected easterly movements in locations over time, primarily due to locations west of the median shifting east. This shift occurred from northern Oklahoma to central Saskatchewan at an average rate of 1.2 km/year (0.3–2.8 km/year). Associated with this directional shift was a decrease in distance of locations from the median in the same region averaging -0.7 km/year (-0.3–-1.3 km/year), suggesting a modest narrowing of the migration corridor. Changes in the corridor over the past 8 decades suggest that agencies and organizations interested in recovery of this species may need to modify where conservation and recovery actions occur. Whooping cranes showed apparent plasticity in their migratory behavior, which likely has been necessary for persistence of a wetland-dependent species migrating through the drought-prone Great Plains. Behavioral flexibility will be useful for whooping cranes to continue recovery in a future of uncertain climate and land use changes throughout their annual range. [ABSTRACT FROM AUTHOR]

The United States is rapidly expanding production of renewable energy to meet increased energy demands and reduce greenhouse gas emissions. Wind energy is at the forefront of this transition. A central challenge is understanding the nexus between wind energy development and its capacity for negative effects on wildlife causing population declines and habitat loss. Collaboration among conservationists and developers, early in the planning process, is crucial for minimizing wind-wildlife conflicts. Such collaborations require data showing where wind and wildlife impacts occur. To meet this challenge and inform decision-making, we provide natural resource agencies and stakeholders information regarding where future wind turbines may occur, and the potential affects on natural resource management, including the conservation of priority species and their habitats. We developed a machine learning model predicting suitability of wind turbine occurrence (hereafter, wind turbine suitability) across an eight-state region in the United States, representing some of the richest areas of wind potential. Our model incorporates predictor variables related to infrastructure, land ownership, meteorology, and topography. We additionally created a constraint layer indicating areas where wind would likely not be developed because of zoning, protected lands, and restricted federal agency proximity guidelines. We demonstrate how the predictive wind turbine suitability model informs conservation planning by incorporating animal movement models, relative abundance models coupled with spatial conservation planning software, and population density models for three exemplar, high priority species often affected by wind energy: whooping cranes (Grus americana), golden eagles (Aquila chrysaetos), and lesser prairie-chickens (Tympanuchus pallidicinctus). By merging the wind turbine and biological models, we identified conservation priority areas (i.e., places sharing high suitability for wind turbines and species use), and places where wind expansion could minimally affect these species. We use our "species-wind turbine occurrence relationships" to demonstrate applications, illustrating how forecasting areas of wind turbine suitability promotes wildlife conservation. These relationships inform wind energy siting to reduce negative ecological impacts while promoting environmental and economic viability. [ABSTRACT FROM AUTHOR]

• Follicular development of in the whooping crane female (Grus americana) can be monitored by weekly ultrasound examination. • Follicular dynamics and hormonal patterns of the female whooping crane are similar to those of other avian species. • The failure of small, yolky follicles to enter the follicular hierarchy that are responsive to follicle stimulating hormone was the likely cause of no egg production in the whooping crane. • Small yolk laden follicles are responsive to follicle stimulating hormone. However, their failure to enter the follicular hierarchy during non-laying cycles of female whooping cranes was considered causative of a lack of egg production. For endangered species managed ex situ , production of offspring is a key factor to ensure healthy and self-sustaining populations. However, current breeding goals for the whooping crane (Grus americana) are impeded by poor reproduction. Our study sought to better understand mechanisms regulating ovarian function in ex situ managed whooping cranes and the regulatory function of the hypothalamic-pituitary–gonadal (HPG) axis in relation to follicle formation and egg laying. To characterize hormonal regulation of follicular development and ovulation, we collected weekly blood samples from six female whooping cranes during two breeding seasons, for a total of 11 reproductive cycles. The plasma samples were assessed for follicle stimulating hormone, luteinizing hormone, estradiol, and progesterone and the yolk precursors vitellogenin and very low-density lipoprotein. Ultrasonographic examination of the ovary was conducted at the time of blood collection. Preovulatory follicles (>12 mm) were present in laying cycles (n = 6) but absent in non-laying cycles (n = 5). The patterns of plasma hormone and yolk precursor concentrations corresponded to the stage of follicle development. Specifically, gonadotropin and yolk precursor concentrations increased as follicles transitioned from the non-yolky to yolky stage but did not increase further as the follicle advanced to preovulatory and ovulatory stages. Estrogen and progesterone concentrations increased as follicle size increased and reached peak concentrations (P < 0.05) when follicles developed to ovulatory and preovulatory stages, respectively. While overall mean circulating gonadotropin, progesterone, and yolk precursor concentrations did not differ for laying versus non-laying cycles, mean plasma estradiol in laying cycles was significantly higher than that in non-laying cycles. In summary, the findings suggested that disruption of mechanisms regulating follicle recruitment is likely responsible for the oviposition failure of the captive female whooping crane. [ABSTRACT FROM AUTHOR]

Available stopover habitats with quality foraging opportunities are essential for migrating waterbirds, including Whooping Crane (Grus americana). Several studies have evaluated habitats used by Whooping Crane for roosting throughout its migration corridor; however, habitats associated with foraging and other diurnal activities have received less attention. We used data collected from 42 Whooping Crane individuals that included 2169 diurnal use locations within 395 stopover sites evaluated during spring 2013 to fall 2015 to assess diurnal habitat selection throughout the U.S. portion of the migration corridor. We found that Whooping Crane selected wetland land-cover types (i.e., open water, riverine, and semipermanent wetlands) and lowland grasslands for diurnal activities over all other land-cover types that we evaluated, including croplands. Whooping Crane generally avoided roads, and avoidance varied based on land-cover class. There has been considerable alteration and destruction of natural wetlands and rivers that serve as roosting and foraging sites for migrating Whooping Crane. Given recent droughts and the likelihood of future landscape changes within the migration corridor, directing conservation efforts toward protecting and enhancing wetland stopover areas may prove critical for continued growth of the last remaining wild population of Whooping Crane. Future studies of this Whooping Crane population should focus on specific wetland complexes and riverine sites throughout the migration corridor to identify precise management actions that could be taken to enhance and protect these imperilled land-cover types.

Pair bonds can provide social benefits to long-term monogamous species alongside their benefits for reproduction. However, little is known about when these bonds form, in particular how long they are present before breeding. Previous studies of pair formation in long-term monogamous birds have been rather data-limited, but for many migratory birds they report pair formation on the wintering grounds. We provide the first systematic investigation of prebreeding association patterns of long-term monogamous pairs by examining entire life histories based on tracking data of migratory whooping cranes, Grus americana . We found that a substantial portion (62%) of breeding pairs started associating at least 12 months before first breeding, with 16 of 58 breeding pairs beginning to associate over 2 years before first breeding. For most pairs, these associations with future breeding partners also became unique and distinguishable from association patterns with nonpartner individuals 12 months before first breeding. In addition, 60% of pair associations began before at least one partner had reached nominal sexual maturity. Most pairs began associating in the late spring upon arrival at the summer grounds, while associations beginning at other times of the year were rare. Patterns in the associations of pairs prior to breeding can point to the potential benefits of prebreeding relationships, for instance providing support in competitive interactions or increasing partner familiarity. [ABSTRACT FROM AUTHOR]

Eleven of 15 species of cranes (family: Gruidae) are considered vulnerable or endangered, and the increase of agriculture and aquaculture at the expense of natural wetlands and grasslands is a threat to Gruidae worldwide. A reintroduced population of Whooping Crane (Grus americana) was studied in coastal and agricultural wetlands of Louisiana and Texas, USA. The objectives were to compare Whooping Crane movements across seasons, quantify multiscale habitat selection, and identify seasonal shifts in selection. Whooping Cranes (n = 53) were tracked with satellite transmitters to estimate seasonal core-use areas (50% home range contours) via Brownian bridge movement models and assess habitat selection. Whooping Crane core-use areas (n = 283) ranged from 4.7 to 438.0 km², and habitat selection changed seasonally as shallow-water availability varied. Whooping Crane core-use areas were composed of more fresh marsh in spring/summer, but shifted towards rice and crawfish (Procambarus spp.) aquaculture in the fall/winter. Within core-use areas, aquaculture was most strongly selected, particularly in fall when fresh marsh became unsuitable. Overall, the shifting of Whooping Crane habitat selection over seasons is likely to require large, heterogeneous areas. Whooping Crane use of agricultural and natural wetlands may depend on spatio-temporal dynamics of w-ater depth. [ABSTRACT FROM AUTHOR]

Breeding sandhill cranes Antigone canadensis and released captive-reared whooping cranes Grus americana have coexisted in central Wisconsin since 2001. Despite 15 y of reintroduction efforts, the reproductive success of these whooping cranes has been near zero. Preliminary data suggest sandhill cranes nesting in central Wisconsin have apparent nest success rates that are similar to those reported from other populations in the region (∼50%). One hypothesized cause of the whooping crane population's low reproductive success is nest abandonment induced by blood-feeding ornithophilic black flies Diptera: Simuliidae. Species-specific differences in selection of nest sites could influence the abundance of black flies at nests and affect reproductive success rates. We measured multiple vegetative and hydrologic characteristics at 35 sandhill crane nests, 20 whooping crane nests, and 164 randomly selected locations at 5- and 200-m scales. We were unable to detect a species-specific difference in vegetation characteristics within 5 m of nest sites. At the 200-m scale, sandhill cranes built nests at sites with slightly greater coverage of woody vegetation than whooping cranes. Differences observed between nest sites of sandhill and whooping cranes appeared to be slight and likely insufficient to explain the dramatic differences in reproductive success in central Wisconsin. [ABSTRACT FROM AUTHOR]

Location error occurs when the true location is different than the reported location. Because habitat characteristics at the true location may be different than those at the reported location, ignoring location error may lead to unreliable inference concerning species-habitat relationships., We explain how a transformation known in the spatial statistics literature as a change of support (COS) can be used to correct for location errors when the true locations are points with unknown coordinates contained within arbitrary shaped polygons., We illustrate the flexibility of the COS by modelling the resource selection of Whooping Cranes ( Grus americana) using citizen contributed records with locations that were reported with error. We also illustrate the COS with a simulation experiment., In our analysis of Whooping Crane resource selection, we found that location error can result in up to a five-fold change in coefficient estimates. Our simulation study shows that location error can result in coefficient estimates that have the wrong sign, but a COS can efficiently correct for the bias. [ABSTRACT FROM AUTHOR]

Birds are altering the phenology of critical life history events, including migration, in response to the effects of global climate change. Whooping Cranes ( Grus americana) are one of the most critically endangered birds in the world. Their remnant population, referred to as the Aransas-Wood Buffalo Population, numbers between 300-400 individuals and migrates between the U.S. Gulf of Mexico coast and north-central Canada twice each year. Previous analyses suggested Whooping Crane migration was temporally constant in spring and fall. New analyses of observations spanning 1942-2016 show Whooping Crane migration is now occurring earlier in spring by approximately 22 days and later in fall by approximately 21 days. Spring temperatures have also increased in the migration corridor during the same period; however, there is no apparent temperature pattern during the fall. In spring, earlier migrating Whooping Cranes stopped over for longer periods of time compared to late-migrating cranes. This result may be partially explained by single Whooping Cranes migrating with earlier migrating Sandhill Cranes ( Antigone canadensis). These results have important conservation implications as the timing of Whooping Crane migration and availability of the habitat and foraging resources, including those associated with agriculture, on which this species relies will be increasingly affected by climate change. [ABSTRACT FROM AUTHOR]

Summary: Identifying climatic drivers of an animal population's vital rates and locating where they operate steers conservation efforts to optimize species recovery. The population growth of endangered whooping cranes (Grus americana) hinges on juvenile recruitment. Therefore, we identify climatic drivers (solar activity [sunspots] and weather) of whooping crane recruitment throughout the species’ life cycle (breeding, migration, wintering). Our method uses a repeated cross‐validated absolute shrinkage and selection operator approach to identify drivers of recruitment. We model effects of climate change on those drivers to predict whooping crane population growth given alternative scenarios of climate change and solar activity. Years with fewer sunspots indicated greater recruitment. Increased precipitation during autumn migration signified less recruitment. On the breeding grounds, fewer days below freezing during winter and more precipitation during breeding suggested less recruitment. We predicted whooping crane recruitment and population growth may fall below long‐term averages during all solar cycles when atmospheric CO2 concentration increases, as expected, to 500 ppm by 2050. Species recovery during a typical solar cycle with 500 ppm may require eight times longer than conditions without climate change and the chance of population decline increases to 31%. Although this whooping crane population is growing and may appear secure, long‐term threats imposed by climate change and increased solar activity may jeopardize its persistence. Weather on the breeding grounds likely affects recruitment through hydrological processes and predation risk, whereas precipitation during autumn migration may influence juvenile mortality. Mitigating threats or abating climate change should occur within ≈30 years or this wild population of whooping cranes may begin declining. [ABSTRACT FROM AUTHOR]