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Midcontinent sandhill cranes (Antigone canadensis) are managed as a single population, but hunting regulations are structured so harvest is targeted towards the more numerous lesser sandhill cranes (A. c. canadensis). However, research indicates that greater sandhill cranes (A. c. tabida) have been disproportionally exposed to harvest at a rate exceeding their proportion within the midcontinent population. In addition, harvest has increased 22% per year in the U.S. Central Flyway states. The midcontinent population appears to be growing in recent years, but variability in annual abundance estimates has increased substantially. With limited resources and harvest management uncertainty increasing, we developed methods for a citizen science, photography‐based harvest survey to estimate age and subspecies composition of harvested midcontinent sandhill cranes. To develop survey methods, we collected physical parts from 284 sandhill cranes in North Dakota in 2019 and 2020. We manually measured the culmen and tarsus using calipers, and digitally measured these parts using photographs and computer software. All digitally derived measurements were 2.5% to 5.9% larger than manual measurements; therefore, we developed linear models that adjusted digital measurements, facilitating subspecies prediction using an existing morphometric‐based technique. In 2021, we requested an equal number of hunters to participate using 2 data collection methods to test if hunters could reliably take photographs suitable for digital measurement. Collection method 1 involved photographing the head and leg simultaneously, and Collection method 2 involved photographing the head only. Hunters submitted a total of 239 photographs. Only 80 of these photographs were submitted using Collection method 1, and 72% were suitable for digital measurement. Conversely, hunters submitted twice as many photographs using Collection method 2, and 88% of these photographs were deemed suitable. Although obtaining the tarsus measurement slightly improved subspecies predictability, Collection method 2 increased participation and usable data. We believe our results could be used to develop an operational survey of age and subspecies composition of midcontinent sandhill cranes, wherein a sample of crane hunters throughout the midcontinent population range would be asked to electronically submit a photograph of the head of each bird they harvest. A time series of age and subspecies composition of this population would provide managers with valuable information and improve harvest management at minimal additional cost and burden, compared to a traditional parts collection survey administered by mail. [ABSTRACT FROM AUTHOR]

Copyright of Avian Conservation & Ecology is the property of Resilience Alliance and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Age-structured population models require reliable estimates of cohort-specific survival rates, yet vital rates of younger age classes are often difficult to estimate because of the logistical challenges of monitoring young animals. As part of a study of sandhill cranes Antigone canadensis in the zone of contact between breeding distributions of the Eastern Population and Midcontinent Population in Minnesota, we monitored first summer survival of 34 sandhill cranes (hereafter colts) by using very-high-frequency and global positioning system–global system for mobile communications transmitters. We estimated daily survival probabilities from 19 to 120 d posthatch by using a generalized linear model accounting for interval censoring, resulting in an estimated period survival rate of 0.52 (90% CI, 0.36–0.71) over summer (100 d). Estimated daily probabilities of survival increased as colts became older and fledged (at 70–75 d posthatch), when they presumably became less vulnerable to predation. Causes of mortality were mostly unknown aside from one case of a collision with a vehicle. There is a scarcity of published colt survival rate estimates for sandhill cranes, and what is available varies widely by study site. Region-specific sandhill crane colt survival rate estimates can inform future management efforts and inform population dynamics research and overall natural history knowledge of sandhill cranes. [ABSTRACT FROM AUTHOR]

Two crane species, whooping cranes (Grus americana) and sandhill cranes (Antigone canadensis), overwinter along the Texas Gulf Coast. Periodic, extreme drought conditions have prompted concerns that potential freshwater limitations could hinder conservation of cranes, especially endangered whooping cranes. In response, land managers constructed and maintained freshwater ponds in upland areas near saltmarshes on the wintering grounds. We monitored 30 of those constructed ponds using camera traps (1 Oct 2013–31 May 2014) to quantify crane visits. For each species, we modeled pond visits as a function of migration phenology and environmental variables at 2 scales. Pond‐scale variables included distance to saltmarsh and monthly salinity, and broad‐scale variables included bay salinity, drought index, and tide level. We found pond visits by both crane species followed migration phenology with the greatest pond use in January–February. Both crane species visited ponds more on the mainland than on Matagorda Island. Sandhill crane visits were fewer at ponds with higher salinities and those filled by well water. Cranes visited ponds during the diurnal period and tended to avoid visiting ponds during the first 10% of the day. Pond visits by whooping cranes were ≤0.15 times/pond/day and by sandhill cranes were ≤0.28 times/pond/day. Our results suggested crane visits to constructed ponds may not be as frequent as once assumed nor driven by tidal and salinity conditions in the bay. The greater number of crane visits to constructed ponds on the mainland compared to Matagorda Island may be related to shrub encroachment around natural freshwater swale wetlands on the mainland, which is not as prevalent of a problem on the island. With proper management, swales on the mainland may provide alternatives to constructed ponds for cranes to obtain freshwater and forage. [ABSTRACT FROM AUTHOR]

Sandhill cranes (Antigone canadensis) were broadly extirpated from much of their historical range in North America at the beginning of the twentieth century. Various conservation‐related legislation, such as the United States Migratory Bird Treaty Act, have assisted with population recovery. The eastern population of sandhill cranes has been growing rapidly since the 1980s and is thought to have expanded its geographic range to Quebec, Canada. Understanding the colonization and habitat use by the species in previously unoccupied breeding areas is necessary to develop and apply management measures. Using a dynamic occupancy modeling approach, we investigated the recent colonization and extirpation patterns of sandhill cranes in Quebec from 2004–2019. We combined data from 3 data sets (helicopter surveys, breeding bird atlas surveys, and eBird) to increase the spatial coverage and the number of species occurrence records while accounting for imperfect detection probability. Detection probability was highest for the helicopter survey (0.70), whereas the 2 other data sets had relatively low detection levels (0.10–0.26). Based on a simulation study, we found that excluding the eBird data from the analysis produced more biased estimates than excluding the atlas and helicopter survey data sets. Throughout the study, sandhill cranes seemed to have completed their colonization of western Quebec and only recently started to nest in eastern areas. Initial occupancy increased with wetland cover and colonization probability increased weakly with the cover of agricultural areas, suggesting that in our study area sandhill cranes rely essentially on natural wetlands during the breeding season. [ABSTRACT FROM AUTHOR]

Collisions with anthropogenic structures by long-distance migrants and threatened and endangered species are a growing global conservation concern. Increasing the visibility of these structures may reduce collisions but may only be accepted by local residents if it does not create a visual disturbance. Recent research has shown the potential for ultraviolet (UV) light, which is nearly imperceptible to humans, to mitigate avian collisions with anthropogenic structures. We tested the effectiveness of two UV (390–400 nm) Avian Collision Avoidance Systems (ACASs) at reducing collisions at two 260-m spans of marked power lines at the Iain Nicolson Audubon Center at Rowe Sanctuary, an important migratory bird stopover location in Nebraska. We used a randomized design and a tiered model selection approach employing generalized linear models and the Akaike Information Criterion to assess the effectiveness of ACASs considering environmental (e.g., precipitation) and detection probability (e.g., migration chronology) variables. We found focal (assessed power line) and distal (neighboring power line) ACAS status and environmental variables were important predictors of avian collisions. Our top model suggests that the focal ACAS illumination reduced collisions by 88%, collisions were more likely at moderate (10–16 km/h) compared to lower or higher wind speeds, and collision frequency decreased with precipitation occurrence. Our top model also indicates that the distal ACAS illumination reduced collisions by 39.4% at the focal power line when that ACAS was off, suggesting a positive “neighbor effect” of power line illumination. Although future applications of ACASs would benefit from additional study to check for potential negative effects (for example, collisions involving nocturnal foragers such as bats or caprimulgiform birds drawn to insects), we suggest that illuminating power lines, guy wires, towers, wind turbines, and other anthropogenic structures with UV illumination will likely lower collision risks for birds while increasing human acceptance of mitigation measures in urban areas.

Infrastructure development can affect avian populations through direct collision mortality. Estimating the exposure of local bird populations to the risk of direct mortality from infrastructure development requires site‐ and species‐specific data, which managers may find difficult to obtain at the scale over which management decisions are made. We quantify the potential exposure of sandhill cranes (Antigone canadensis) to collision with horizontal structures (e.g., transmission lines) within vital wintering grounds of the Middle Rio Grande Valley (MRGV), New Mexico, USA, 2014–2020. Limited maneuverability and visual acuity make sandhill cranes vulnerable to collisions with infrastructure bisecting their flight paths. We used data from 81 global positioning system (GPS)‐tagged cranes to estimate the spatially explicit flight height distribution along the MRGV, the passage rate across hypothetical transmission lines, and the resulting exposure rate (exposed passes/crane/day). The exposure rate ranged from 0–0.28 exposed passes/crane/day (median = 0.015) assuming an exposure zone of 7–60 m above ground level, and identified hotspots of potential exposure within the MRGV. Mapped exposure rates can assist in the siting of proposed high‐voltage transmission lines, or other infrastructure, to limit effects on sandhill cranes and other avian species at risk of collision. Our approach can be replicated and applied in similar situations where birds are exposed to possible collision with power lines. © 2021 The Wildlife Society. [ABSTRACT FROM AUTHOR]

Sandhill cranes (Antigone canadensis) inhabiting the midcontinent of North America have been hunted since the 1960s under management goals of maintaining abundance, retaining geographic distribution, and maximizing sustainable harvest. Some biologists have raised concerns regarding harvest sustainability because sandhill cranes have lower reproductive rates than other game birds. We summarized demographic information in an age‐structured matrix model to better understand population dynamics and harvest. Population indices and recovered harvest since the early 1980s suggest midcontinent sandhill cranes have experienced an average long‐term annual growth of 0.9%; meanwhile, harvest has increased 1.8% annually. Adult survival and recruitment rates estimated from field data required modest adjustments (1–3%) so that model‐derived growth rates matched growth estimated from a long‐term survey (0.887 adult survival and 0.199 females/breeding female). Considering 0.9% long‐term annual growth, sandhill cranes could be harvested at a rate of 6.6% if harvest was additive to natural mortality (assumed to be 0.05) or 11.3% if harvest mortality compensated for natural mortality. Life‐history characteristics for long‐lived organisms and demographic evidence suggested that hunter harvest was primarily additive. Differential harvest rates of segments of sandhill cranes in the midcontinent population derived from differential exposure to hunting suggested potentially unsustainable harvest for greater sandhill cranes (A. c. tabida) from 2 breeding segments. Overall, demographic evidence suggests that the harvest of sandhill cranes in the midcontinent population has been managed sustainably. Monitoring activities that reduce nuisance variation and estimate vital and harvest rates by subspecies would support continued management of sandhill cranes that are of interest to hunters and bird watchers. Published 2020. This article is a U.S. Government work and is in the public domain in the USA. Long‐term survey estimates and population model results suggest that harvest of sandhill cranes from the midcontinent population has been implemented sustainably. Managing this population as a single entity involves potential risks to specific groups of sandhill cranes; therefore, improved monitoring activities that reduce nuisance variation and estimate vital and harvest rates would support continued management. [ABSTRACT FROM AUTHOR]

Copyright of Avian Conservation & Ecology is the property of Resilience Alliance and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sandhill Cranes Antigone canadensis exhibit delayed sexual maturity and breeding, and therefore juvenile Cranes searching for suitable territories to occupy have different ecological constraints on movements than adults, which must defend a territory and raise young. We used fine‐scale GPS telemetry data to characterize and compare movements of adult and juvenile Cranes near the boundary between two populations in Minnesota, USA, from arrival on natal areas in the spring until staging prior to autumn migration. Juvenile and adult Cranes had marked differences in movement patterns throughout the breeding season. Juveniles were more likely than adults to display long‐distance movements: they revisited areas less frequently throughout the breeding season and they had lower average residence times. [ABSTRACT FROM AUTHOR]

ABSTRACT Sandhill cranes (Antigone canadensis) are long‐lived birds with relatively low recruitment rates, making accurate knowledge of abundance and distribution critical for well‐informed harvest management. Minnesota, USA, is one of few states containing portions of 2 distinct breeding populations of greater sandhill cranes (A. c. tabida)—the Mid‐continent Population (MCP) and Eastern Population (EP). Historically, the breeding range of MCP cranes in Minnesota was restricted to the extreme northwestern portion of the state, whereas the breeding range of EP cranes was limited to the east–central part of the state with a large area of separation between the 2 populations. Whereas MCP cranes have exhibited stable population estimates over time, EP cranes are currently experiencing a significant increase in population size and a concurrent expansion of breeding range. Our objectives were to evaluate the current range boundaries of the 2 populations in Minnesota and determine whether the populations overlap on their breeding areas and autumn staging grounds. We captured and attached Global Positioning System–Global System for Mobile Communications transmitters to 50 cranes in the zone between the historical breeding‐range boundaries of the 2 populations. Movements of cranes revealed that EP cranes have greatly expanded their breeding range in Minnesota while MCP cranes have experienced more moderate range expansion in the state. Results of this study provide the first documentation of overlap between the breeding ranges of EP and MCP sandhill cranes. Our results also suggest that staging areas in northwestern Minnesota, where recreational harvest targeted at MCP cranes was allowed beginning in 2010, are being used by both populations and there is overlap in migration corridors, as evidenced by 4 cranes that used both the Mississippi and Central Flyways. © 2017 The Wildlife Society.

Breeding Bird Survey (BBS) data indicate that the Florida population of the nonmigratory Florida Sandhill Crane (Antigone canadensis pratensis) has been increasing for 50 years despite substantial habitat loss and a recent period of extended drought. We generated BBS route-specific population trends for 1966-2016 to identify locations in Florida that had experienced significant increases or declines to better understand the statewide population growth. We also assessed whether changes in land cover over time were correlated with local increases or decreases in the Sandhill Crane population. Finally, we explored how drought during the breeding season affected the number of cranes detected during the BBS and the number of young cranes detected in a fall post-reproductive survey we conducted during 1991-2016. Of the 42 BBS routes on which cranes were observed in ≥ 4 years, populations increased on 17 (40%) and declined on one (2%), and no change was detected on 24 (57%). Routes with positive population growth occurred throughout the breeding range, with one hot spot of growth occurring in the northwest region of central Florida. Change in five primary land cover types (grassland, wetland, scrub/successional, woodland, urban) during 1985-2016 did not predict changes in Sandhill Crane populations. Drought conditions during a prior year's breeding season were negatively correlated with BBS counts, and within-season drought conditions were negatively correlated with juvenile crane counts on the post-reproductive surveys. Productivity rates in all but the driest years were similar to those associated with stable or growing crane populations. Continued monitoring is warranted because the longevity of adult cranes could mask an impending population decline and because little is known about the cranes that reside in the suburban landscapes that make up an increasingly large proportion of Florida's landscapes.

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]

Sandhill Cranes ( Antigone canadensis) of the midcontinent population (MCP) and Rocky Mountain population (RMP) are migratory game birds with stable populations that travel between Canada and the southern US and Mexico. In the winters of 2012-14, we performed gross and histologic examinations of 43 hunter-harvested Sandhill Cranes in Texas (MCP) and New Mexico (RMP) to assess the impact of disease on populations. Lesions were significantly more common in the MCP relative to the RMP, likely reflecting differential environmental exposure to pathogens and parasites. Grossly, liver nodules and esophageal granulomas were present in 8-39% of birds. In feces from over half of birds, we found coccidian oocysts with mitochondrial gene sequences identical to those of Eimeria gruis and Eimeria reichenowi previously obtained from sympatric Whooping Cranes ( Grus americana). Over one-quarter of birds had liver and cardiac lesions suggestive of disseminated visceral coccidiosis. We documented proliferative colitis due to Cryptosporidium in a wild Sandhill Crane. Additionally, several endoparasites were found in histologic sections from several cranes, including a bird with respiratory trematodiasis and two birds with Tetrameres sp. in the proventriculus associated with ductal ectasia. In addition to describing lesions and parasites that impact Sandhill Crane health, these pathology data may also be relevant for the conservation of endangered Whooping Cranes using a surrogate species approach. [ABSTRACT FROM AUTHOR]

ABSTRACT Sandhill cranes ( Antigone canadensis) are long-lived birds with relatively low recruitment rates, making accurate knowledge of abundance and distribution critical for well-informed harvest management. Minnesota, USA, is one of few states containing portions of 2 distinct breeding populations of greater sandhill cranes ( A. c. tabida)-the Mid-continent Population (MCP) and Eastern Population (EP). Historically, the breeding range of MCP cranes in Minnesota was restricted to the extreme northwestern portion of the state, whereas the breeding range of EP cranes was limited to the east-central part of the state with a large area of separation between the 2 populations. Whereas MCP cranes have exhibited stable population estimates over time, EP cranes are currently experiencing a significant increase in population size and a concurrent expansion of breeding range. Our objectives were to evaluate the current range boundaries of the 2 populations in Minnesota and determine whether the populations overlap on their breeding areas and autumn staging grounds. We captured and attached Global Positioning System-Global System for Mobile Communications transmitters to 50 cranes in the zone between the historical breeding-range boundaries of the 2 populations. Movements of cranes revealed that EP cranes have greatly expanded their breeding range in Minnesota while MCP cranes have experienced more moderate range expansion in the state. Results of this study provide the first documentation of overlap between the breeding ranges of EP and MCP sandhill cranes. Our results also suggest that staging areas in northwestern Minnesota, where recreational harvest targeted at MCP cranes was allowed beginning in 2010, are being used by both populations and there is overlap in migration corridors, as evidenced by 4 cranes that used both the Mississippi and Central Flyways. © 2017 The Wildlife Society. [ABSTRACT FROM AUTHOR]