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Climate change has myriad impacts on ecosystems, but the mechanisms by which it affects individual species can be difficult to pinpoint. One strategy to discover such mechanisms is to identify a specific ecological factor related to survival or reproduction and determine how that factor is affected by climate. Here we used Landsat imagery to calculate water clarity for 127 lakes in northern Wisconsin from 1995 to 2021 and thus investigate the effect of clarity on the body condition of an aquatic visual predator, the common loon (Gavia immer). In addition, we examined rainfall and temperature as potential predictors of water clarity. Body mass tracked July water clarity strongly in loon chicks, which grow chiefly in that month, but weakly in adult males and females. Long‐term mean water clarity was negatively related to chick mass but positively related to adult male mass, suggesting that loons foraging in generally clear lakes enjoy good foraging conditions in the long run but might be sensitive to perturbations in clarity during chick‐rearing. Finally, chick mass was positively related to the density of docks, perhaps because angling removes large fishes and thus boosts the abundance of the small fishes on which chicks depend. Water clarity itself declined strongly from 1995 to 2021, was negatively related to July rainfall, and was positively related to July air temperature. Our findings identified both long‐term and short‐term water clarity as strong predictors of loon foraging efficiency, and suggest that climate change, through water clarity, impacts freshwater ecosystems profoundly. Moreover, our results identified the recent decrease in water clarity as a likely cause of population decline in common loons. [ABSTRACT FROM AUTHOR]

Age often indicates phenotypic quality, ecological experience or social status in animals. Consequently, behavioural signals in territorial animals that accurately convey age to potential mates or rivals might provide useful information for both signaller and receiver about the likelihood of aggression. We tested whether male territorial yodels convey information about age in the common loon, Gavia immer. Using a sample of male loons of known age, we found that the dominant frequency of Fintro3, a dominant syllable in the beginning sequence of a male yodel, increases strongly with age, but we were unable to replicate an earlier finding linking Fintro3 to body mass. We hypothesize that older male loons, which yodel more often than young males, might do so as a means to advertise their age and higher likelihood of aggression to potential rivals. • We tested whether male yodels convey information about age in common loons. • Dominant frequency of a dominant syllable (Fintro3) in male yodels increased with age. • Fintro3 was found previously to decrease with body mass, but not in our study. • Age may have a more significant effect on yodel acoustics than body mass. • Older males may yodel more often to advertise their age and likelihood of aggression. [ABSTRACT FROM AUTHOR]

Common loon (Gavia immer (Brünnich, 1764)) foraging patterns and the relative importance of cisco (Coregonus artedi Lesueur, 1818) in the diets of loons were evaluated for the Whitefish Chain of Lakes, a set of coldwater cisco refuge lakes in Minnesota, USA. Environmental DNA metabarcoding of loon fecal samples detected 15 fish species. Yellow perch (Perca flavescens (Mitchill, 1814)), mimic shiner (Notropis volucellus (Cope, 1865)), and cisco were the most prominent prey detected across the study lakes. We observed a shift in fish species consumed, with increases in detections of mimic shiner and cisco DNA among loon fecal samples collected in August and September. In some locations, suitable oxythermal habitat became restricted throughout the summer, forcing cisco into surface waters, which potentially increased their vulnerability to loon predation. Conversely, large foraging aggregations of loons were observed during late summer through fall at locations with ample oxythermal habitat and abundant cisco populations. We hypothesize that cisco were sought by loons as a high-calorie prey resource prior to migration. Conservation efforts directed at preserving water quality in important cisco refuge lakes are likely to benefit common loons through enhancement of both the forage base, for resident and migrating birds, and breeding habitat suitability. [ABSTRACT FROM AUTHOR]

Most studies of vertebrate breeding success have been unable to pinpoint the cause for a simple and almost universal pattern: its steady increase during an animal's lifetime. Yet potential causes of increased breeding success have profound implications for the evolution of reproductive behaviour. An age-related increase might come about through (1) higher breeding investment by older animals, (2) breeding improvement through learning, (3) better reproductive coordination between familiar mates or (4) accumulated benefits of site familiarity. We used mixed models to investigate age-related predictors of hatching and fledging success in a population of common loons, Gavia immer , that contained many known-age breeders and has been under continuous study for 30 years. Hatching success of breeding pairs increased between the female's first and second years on territory but did not increase with further female experience. In contrast, pair hatching success increased in proportion to the cube root of the males' residency on a territory, a pattern that persisted beyond 15 years. Hatching date was earlier for pairs that had spent at least 1 year together and in which the female was young but had spent at least one prior year on the territory. Fledging rate of hatched young was greater among pairs that nested early but decreased with female age, an apparent indication of female reproductive senescence. Overall, breeding pairs fledged more young when the breeding male had many years of experience on the territory and the breeding female had been on territory for at least 1 year and was of moderate age. Our findings highlight the persistent influence of both site familiarity and chronological age on reproductive fitness. • We examined attributes of male and female loons that affect reproductive success (RS). • Territory familiarity improved female RS only between the first and second years. • Age negatively affected RS in young and old females but made no difference in males. • Males showed increases in RS for over 15 years when they remained on familiar territory. • Mate familiarity had little impact on RS, but pairs with ≥1 year together nested earlier. [ABSTRACT FROM AUTHOR]

Identification of geographic linkages among breeding, migratory and wintering common loon Gavia immer populations is needed to inform regional and national conservation planning efforts and compensation of loons lost during marine oil spill events. Satellite telemetry and archival geolocator tags were used to determine the migration patterns and wintering locations of breeding adult and young of the year juvenile common loons captured and marked on lakes in Minnesota, Wisconsin and Michigan. Adult loons typically traveled from breeding lakes, often via larger staging lakes, to the Great Lakes (primarily Lake Michigan) and then on to wintering areas. Most radiomarked juvenile common loons utilized natal lakes or local lakes through mid‐November. Subsequently, the first fall migration of juvenile loons was generally initiated later, and more direct and quicker to wintering areas relative to adults. Among adult (n = 103) and juvenile (n = 23) loons that completed fall migration, most wintered in the Gulf of Mexico (GOM), with smaller proportions wintering off the southern Atlantic Coast or impoundments in the southeastern United States. Spring migration of adults to breeding lakes was less prolonged than fall migration, with adult male loons tending to depart wintering areas earlier than adult females. Juvenile common loons migrated during their first spring from wintering sites in the GOM to summer in the Gulf of St Lawrence/Nova Scotia Coastal region. Juvenile mortality was largely linked to parasitic infection and emaciation; spring appeared to be a survival bottleneck among juvenile loons monitored in our study. Our results identify several areas where common loon conservation efforts could be directed to protect key habitats and minimize stressors during the non‐breeding period. [ABSTRACT FROM AUTHOR]

Understanding how risk factors affect populations across their annual cycle is a major challenge for conserving migratory birds. For example, disease outbreaks may happen on the breeding grounds, the wintering grounds, or during migration and are expected to accelerate under climate change. The ability to identify the geographic origins of impacted individuals, especially outside of breeding areas, might make it possible to predict demographic trends and inform conservation decision‐making. However, such an effort is made more challenging by the degraded state of carcasses and resulting low quality of DNA available. Here, we describe a rapid and low‐cost approach for identifying the origins of birds sampled across their annual cycle that is robust even when DNA quality is poor. We illustrate the approach in the common loon (Gavia immer), an iconic migratory aquatic bird that is under increasing threat on both its breeding and wintering areas. Using 300 samples collected from across the breeding range, we develop a panel of 158 single‐nucleotide polymorphisms (SNP) loci with divergent allele frequencies across six genetic subpopulations. We use this SNP panel to identify the breeding grounds for 142 live nonbreeding individuals and carcasses. For example, genetic assignment of loons sampled during botulism outbreaks in parts of the Great Lakes provides evidence for the significant role the lakes play as migratory stopover areas for loons that breed across wide swaths of Canada, and highlights the vulnerability of a large segment of the breeding population to botulism outbreaks that are occurring in the Great Lakes with increasing frequency. Our results illustrate that the use of SNP panels to identify breeding origins of carcasses collected during the nonbreeding season can improve our understanding of the population‐specific impacts of mortality from disease and anthropogenic stressors, ultimately allowing more effective management. [ABSTRACT FROM AUTHOR]

The article presents a summary of the activities of the Kansas Bird Record Committee for the year 2020 including the number of reports evaluated, resolution of previous year records, and records that were not accepted.

We investigated both social and foraging plasticity in a population of Common Loons (Gavia immer) that overwinter inland on Lake Jocassee Reservoir, South Carolina, using transects and time-activity budgets from 4 January to 10 March 2017. Loons were observed as either solitary individuals (65%) or in groups (35%, i.e., within ≤5 body lengths of another loon). Loons were more social (i.e., in groups) on transects with a river mouth (40.9% ± 7.1) than on transects without a river mouth (24.2% ± 5.4). The mean (± SE) dive duration for solitary loons was 71.3 ± 7.7 s (n = 46, range 15–219 s) and several dives exceeded 2 min (22.2%, 10/46). In contrast, 15 foraging flocks were characterized by numerous shallow dives of <20 s. The mean group size (± SE) was 6.9 ± 0.8 individuals and group foraging bouts lasted 8.3 ± 1.2 min. In addition, Horned Grebes (Podiceps auritus) and Ring-billed Gulls (Larus delawarensis) joined loons forming multispecies foraging flocks, 26.7% and 13.3% of the time, respectively. These data indicate Common Loons wintering at Lake Jocassee are social and exhibit foraging plasticity. [ABSTRACT FROM AUTHOR]

Together climate and land‐use change play a crucial role in determining species distribution and abundance, but measuring the simultaneous impacts of these processes on current and future population trajectories is challenging due to time lags, interactive effects and data limitations. Most approaches that relate multiple global change drivers to population changes have been based on occurrence or count data alone.We leveraged three long‐term (1995–2019) datasets to develop a coupled integrated population model‐Bayesian population viability analysis (IPM‐BPVA) to project future survival and reproductive success for common loons Gavia immer in northern Wisconsin, USA, by explicitly linking vital rates to changes in climate and land use.The winter North Atlantic Oscillation (NAO), a broad‐scale climate index, immediately preceding the breeding season and annual changes in developed land cover within breeding areas both had strongly negative influences on adult survival. Local summer rainfall was negatively related to fecundity, though this relationship was mediated by a lagged interaction with the winter NAO, suggesting a compensatory population‐level response to climate variability.We compared population viability under 12 future scenarios of annual land‐use change, precipitation and NAO conditions. Under all scenarios, the loon population was expected to decline, yet the steepest declines were projected under positive NAO trends, as anticipated with ongoing climate change. Thus, loons breeding in the northern United States are likely to remain affected by climatic processes occurring thousands of miles away in the North Atlantic during the non‐breeding period of the annual cycle.Our results reveal that climate and land‐use changes are differentially contributing to loon population declines along the southern edge of their breeding range and will continue to do so despite natural compensatory responses. We also demonstrate that concurrent analysis of multiple data types facilitates deeper understanding of the ecological implications of anthropogenic‐induced change occurring at multiple spatial scales. Our modelling approach can be used to project demographic responses of populations to varying environmental conditions while accounting for multiple sources of uncertainty, an increasingly pressing need in the face of unprecedented global change. [ABSTRACT FROM AUTHOR]

Many species show natal habitat preference induction (NHPI), a behavior in which young adults select habitats similar to those in which they were raised. However, we know little about how NHPI develops in natural systems. Here, we tested for NHPI in juvenile common loons (Gavia immer) that foraged on lakes in the vicinity of their natal lake after fledging. Juveniles visited lakes similar in pH to their natal lakes, and this significant effect persisted after controlling for spatial autocorrelation. On the other hand, juveniles showed no preference for foraging lakes of similar size to their natal one. When lakes were assigned to discrete classes based on size, depth, visibility, and trophic complexity, both juveniles from large lakes and small lakes preferred to visit large, trophically diverse lakes, which contained abundant food. Our results contrast with earlier findings, which show strict preference for lakes similar in size to the natal lake among young adults seeking to settle on a breeding lake. We suggest that NHPI is relaxed for juveniles, presumably because they select lakes that optimize short‐term survival and growth. By characterizing NHPI during a poorly studied life stage, this study illustrates that NHPI can take different forms at different life stages. [ABSTRACT FROM AUTHOR]

Populations of many vertebrates are declining and geographic ranges contracting, largely as a consequence of anthropogenic threats. Many reports of such decline, however, lack the breadth and detail to narrow down its causes. Here we describe population decline in the Common Loon (Gavia immer), a charismatic aquatic bird, based on systematic resighting and measurement of a marked population. During our 27-year investigation, age-adjusted chick mass has fallen by 11%, mortality among young and old chicks has increased by 31% and 82%, respectively, and fledging success has declined by 26%. Meanwhile, the return rate of marked nonbreeders ("floaters") has plunged by 53%, and the adult population overall has declined by 22%. Consistent with the thinning ranks of floaters, the rate of territory eviction has decreased by 52% during the study. Despite the decline in floaters, territory occupancy remains unchanged. However, a matrix model, updated with recent estimates for breeding success, juvenile survival, and senescence, yields a recalculated deterministic population growth rate (λ) of 0.94 for our study population, which suggests that declines in vital rates could lead to a loss of 52% of the current population and a decline of 37% in territory occupancy by 2031. Lack of data on floaters in other upper Midwest and New England loon populations leaves their status in doubt. LAY SUMMARY The adult loon population in northern Wisconsin has declined by 22% over the past 27 years. Numbers of chicks and chick mass have declined significantly. The population of young nonbreeders (floaters) has plummeted by 46%. Despite these steep declines, there has been no measurable drop in the number of territorial pairs. The hidden nature of the Wisconsin decline points out that floater populations can mask major drops in breeding populations and throws into question population trends in other loon populations, whose floater populations are largely unknown. [ABSTRACT FROM AUTHOR]

Another report of the Czech Rarities Committee, working under the Czech Society for Ornithology (CSO), includes records of rare bird species in the Czech Republic submitted for assessment to the Committee in the year 2018 and early 2019. During this period, the Committee resolved altogether 85 records – 68 of them (82%) were accepted, 14 were rejected, and one was withdrawn by the author. Besides that, the report also includes 190 records of species which are subject to registration. In 2018, the Committee was composed of the following members: Jiří Horáček (chair), Jiří Šírek (secretary), Martin Vavřík, David Heyrovský, Jaroslav Šimek, and Michal Šindel. In 2018, the first occurrence of the Canvasback (Aythya valisineria) in the Czech Republic was confirmed – however, the observation was classified in the category D. Furthermore, the second record of the American Wigeon (Mareca americana), eighth record of the Ruddy Duck (Oxyura jamaicensis), eighth and ninth records of the Arctic Redpoll (Acanthis hornemanni), 11th record of the Glaucous Gull (Larus hyperboreus), 13th records of the Sociable Lapwing (Vanellus gregarius) and Terek Sandpiper (Xenus cinereus), and 14th record of the Pectoral Sandpiper (Calidris melanotos) were made. Third to eighth records of the Rosy Starling (Pastor roseus), eighth record of the Greater Spotted Eagle (Clanga clanga), and ninth to 11th records of the Common Loon (Gavia immer) since 1989 were accepted. Eight Yellow-browed Warblers (Phylloscopus inornatus) and 24 Long-legged Buzzards (Buteo rufinus) were recorded. Breeding of the Whooper Swan (Cygnus cygnus) was proved for the second time. In the following list, numbers in brackets in each species show the number of accepted records before 1988, in the years 1989–2017, and in 2018. Where provided, compound numbers such as n+2 indicate that, beside the accepted records, there is an uncertain number of reports not yet considered by the Committee. A dash (–) instead of a number means that records from the particular period were not collected. An asterisk (*) in front of the species name marks a new species for the fauna of the Czech Republic, “(r)” in front of the species name marks species whose records are only subject to registration. In the species registered since 2008, the number of records in the years 2008–2017 and in 2018 is given in brackets. The cases when the bird was first found already in the year 2017 and stayed till 2018, and added records from earlier years are shown in italics. We applied the nomenclature of the IOC World Bird List (version 8.2; IOC 2018). The Czech Rarities Committee is a member of the Association of European Records and Rarities Committees (AERC). See http://fkcso.cz and http://www.aerc.eu. [ABSTRACT FROM AUTHOR]

The article lists several references to common names, genera, species, and authors including Anthus spragueii; Barraga´n-Far´ıas KA; and P´erez-Casanova RA.

Bald Eagles (Haliaeetus leucocephalus) and Common Loons (Gavia immer) have been the subject of intensive recovery efforts over 4 decades in New Hampshire. In the last 2 decades, eagles have increased from 1 to 40 territorial pairs, and loons have increased from 208 to 284 territorial pairs. Eagle predation of loons and loon eggs has been documented in a limited but increasing number of cases. We looked for evidence that this predation has begun to limit loon productivity or provoke territorial shifts to avoid predation during the initial period of Bald Eagle population recovery (1998–2013). Using 16 yr of breeding census data, we found support for the prediction that eagle nest proximity may be contributing to >3% of observed loon nest failures. Our findings indicate that eagles may already be exerting a measurable predation pressure. However, at current eagle densities, this pressure does not explain observed local declines in loon abundance. Our counterfactual analysis identified subsets of the data (e.g., loon nest sites on islands) where eagle nest density had the strongest negative association with loon productivity; it may be a useful tool for similar ecological models. [ABSTRACT FROM AUTHOR]

Common loons (Gavia immer) are at risk of elevated dietary mercury (Hg) exposure in portions of their breeding range. To assess the level of risk among loons in Minnesota (USA), we investigated loon blood Hg concentrations in breeding lakes across Minnesota. Loon blood Hg concentrations were regressed on predicted Hg concentrations in standardized 12‐cm whole‐organism yellow perch (Perca flavescens), based on fish Hg records from Minnesota lakes, using the US Geological Survey National Descriptive Model for Mercury in Fish. A linear model, incorporating common loon sex, age, body mass, and log‐transformed standardized perch Hg concentration representative of each study lake, was associated with 83% of the variability in observed common loon blood Hg concentrations. Loon blood Hg concentration was positively related to standardized perch Hg concentrations; juvenile loons had lower blood Hg concentrations than adult females, and blood Hg concentrations of juveniles increased with body mass. Blood Hg concentrations of all adult common loons and associated standardized prey Hg for all loon capture lakes included in the study were well below proposed thresholds for adverse effects on loon behavior, physiology, survival, and reproductive success. The fish Hg modeling approach provided insights into spatial patterns of dietary Hg exposure risk to common loons across Minnesota. We also determined that loon blood selenium (Se) concentrations were positively correlated with Hg concentration. Average common loon blood Se concentrations exceeded the published provisional threshold. Environ Toxicol Chem 2019;38:524–532. Published 2018 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America. [ABSTRACT FROM AUTHOR]

Nesting birds must often cope with harassment from biting insects, but it is difficult to ascertain what effect such pests might have on breeding success and population dynamics. We tested the hypothesis that a black fly (Simulium annulus) that feeds on the blood of nesting Common Loons (Gavia immer) causes nest abandonment in this charismatic diving bird. In addition, we measured effects of fly-induced abandonment on a loon population, and examined potential predictors of fly abundance and nest abandonment. We also tested a second hypothesis, which holds that loon pairs that abandon a nest owing to flies should often remain at the site for their subsequent nesting attempt, since fly outbreaks last only 1-2 weeks. All predictions of the fly-induced abandonment hypothesis were supported, including strong correlations between fly counts and rate of abandonment, reduced incubation during severe fly years, and increased abandonment during cool springs, which promote longevity of the flies. The correlation between nest abandonment and population breeding success suggests that S. annulus reduced the chick fledging rate by as much as 23% in a year of severe infestation. Fly numbers on loons and their nests were highest when temperatures were high and winds were light. Surprisingly, however, exposure to the prevailing wind increased, not decreased, nest abandonment, perhaps because of wave action. Lake size was inversely and female age directly correlated with abandonment rate, possibly due to food limitation in small lakes and senescence of females, respectively. Finally, pairs that abandoned a first nest renested at the same site with much greater frequency than did pairs that lost eggs to a predator, indicating that loons are capable of responding adaptively to a cause of nest failure that is time- but not space-dependent. [ABSTRACT FROM AUTHOR]

We examined the influence of biological and geographical factors on the levels and patterns of organohalogen contaminants in blood of adult common loons ( Gavia immer ) collected from 20 lakes in Alberta, Canada. The loons were captured in the 2006 and 2007 breeding seasons over a 900 m elevation gradient across the eastern slope of the Canadian Rocky Mountains. While PCBs dominated the composition of these contaminants in loons at all sites (∑PCBs >  p,p’ -DDE > ∑PBDEs > ∑Chlordanes > HCB), p,p’ -DDE and ∑PBDEs were also important, averaging approximately 50% and 20% of total PCB concentrations, respectively. ∑PCBs and ∑PBDEs were higher in males than in females. Inter-lake variation was apparent for contaminant concentrations and patterns and were largely explained by dietary signatures (δ 15 N and δ 13 C) and proximity to a large hydroelectric dam. Mean ∑PCB (19.6 ng/g wet weight (ww)) and organochlorine pesticide (OCP) ( p,p’ -DDE: 11.8 ng/g, cis -nonachlor: 0.10 ng/g, trans -nonachlor: 0.32 ng/g, HCB: 0.34 ng/g ww) concentrations in loons were approximately 4- to 17-fold lower than average concentrations reported in common loons from Atlantic Canada and were well below concentrations which have been associated with impaired reproductive success and eggshell thinning in other piscivorous birds. Dominant PBDE congeners were BDE47, BDE99, and BDE100. The regional mean for ∑PBDEs (4.04 ng/g ww) in loons from the present study was within the range reported for ∑PBDEs in nestling bald eagle plasma from British Columbia. This is the first report of PBDEs in loons and the first report of PCBs and OCPs in common loons from Western North America. [ABSTRACT FROM AUTHOR]

ABSTRACT Poisoning from lead fishing tackle has been identified as the leading cause of mortality in adult common loons ( Gavia immer). As a K-selected species, adult survival is a critical component in the population demography of loons, but the population-level effects of mortality from ingested lead tackle on loons have not been quantified. We used a long-term dataset (1989-2012) on common loon mortality in New Hampshire, USA, to describe the types of lead tackle ingested by loons, investigate methods of ingestion of lead tackle, document the number and rate of adult mortalities resulting from lead tackle, and test for a population-level effect of lead tackle on the loon population in New Hampshire. Nearly half (48.6%) of collected adult mortalities resulted from lead toxicosis from ingested lead fishing tackle, representing an adjusted annual mortality rate of 1.7 ± 0.6% (SD) of the statewide population. Jigs accounted for 52.6% and sinkers for 38.8% of the archived lead tackle objects removed from loons, a higher proportion of jigs than has been reported in previous studies. The timing of lead tackle mortalities and a high incidence of accompanying non-lead associated fishing gear (hooks, fishing line, leaders, swivels, wire), which peaked in July and August, suggest that loons obtain the majority of lead tackle from current fishing activity rather than from a reservoir of lead tackle on lake bottoms. To project the statewide loon population in the absence of lead fishing tackle as a stressor, we constructed a retrospective population model, which re-inserted loons that died from lead tackle into the population, and used linear regression to test for a population-level effect. We defined a population-level effect as a difference in the population growth rate (λ). We estimated that lead tackle mortality reduced the population growth rate (λ) by 1.4% and the statewide population by 43% during the years of the study. This study suggests that replacing lead fishing sinkers and jigs weighing ≤28.4 g with non-toxic alternatives would result in an immediate benefit to the loon population in New Hampshire. © 2017 The Wildlife Society. [ABSTRACT FROM AUTHOR]

Understanding and conserving migratory species requires a method for characterizing the seasonal flow of animals among habitats. Source-sink theory describes the metapopulation dynamics of species by classifying habitats as population sources (i.e. net contributors) or sinks (i.e. net substractors). Migratory species may have non-breeding habitats important to the species (e.g. overwintering or stopover habitats) that traditional source-sink theory would classify as sinks because these habitats produce no individuals. Conversely, existing migratory network models can evaluate the relative contribution of non-breeding nodes, but these models make an equilibrium assumption that is difficult to meet when examining real migratory populations., We extend a pathway-based metric allowing breeding habitats, non-breeding habitats and migratory pathways connecting these habitats to be classified as sources or sinks. Rather than being based on whether place- or season-specific births exceed deaths, our approach quantifies the total demographic contribution from a node or migratory pathway over a flexibly defined yet limited time period across an organism's life cycle. As such, it provides a snapshot of a migratory system and therefore does not require assumptions associated with equilibrium dynamics., We first develop a generalizable mathematical notation and then demonstrate how the metric may be used with two case studies: the common loon ( Gavia immer) and Yellowstone cutthroat trout ( Oncorhynchus clarkii bouvieri). These examples highlight how stressors can impact stopover and wintering habitats (loons) and habitat management targeting migratory pathways can improve population status (trout)., Synthesis and applications. Each of the two case studies presented describes how effects at one location are felt by populations in another through the seasonal flow of individuals. The contribution metric we present should be helpful in allocating regulatory and management attention to times and locations most critical to migratory species persistence. [ABSTRACT FROM AUTHOR]

As the value of a limited resource such as a territory increases, animals should invest more in the defence of that resource. Because reproductive success often depends on the quality of a breeding territory, reproductive success or failure may alter the perceived value of territory and affect an animal's investment in territorial defence. We used common loons Gavia immer to test the hypothesis that animals with recent breeding success would show stronger territorial defence than those with no recent breeding success. Surprisingly, successful loons responded less, not more, to a simulated intrusion. However, birds with success in the previous season also increased their territorial response as the breeding season progressed. In conjunction with past data showing that recently successful loons experience an increase in conspecific intrusions on their territories, we interpret our data to suggest that loons with recent success offset the cost of increased intrusions by adopting a more efficient strategy for territorial defence (e.g. limiting investment in resource defence until the time of the season when it is most critical). [ABSTRACT FROM AUTHOR]

Senescence, increased mortality that occurs among animals of advanced age, impacts behavior and ecology in many avian species. We investigated actuarial, reproductive, and behavioral senescence using capture, marking, and resighting data from a 26-year study of common loons Gavia immer. Territorial residents of both sexes exhibited high annual survival (0.94) until their mid 20s, at which point survival fell to 0.76 and 0.77 in males and females, respectively. Sexual symmetry in actuarial senescence is somewhat surprising in this species, because males make a substantially greater investment in territory defense and chick-rearing and because males engage in lethal contests for territory ownership. Survival of displaced breeders (0.80) was lower than that of territorial residents in both young and old individuals. Old males and females also experienced slightly higher annual probability of eviction (0.16 for males; 0.17 for females) than prime-aged breeders (0.13 for both sexes), indicating senescence in territory defense. Prime-aged males reclaimed territories at a high rate (0.49), in contrast to females of the same age (0.33). However, old males resettled with success (0.35) similar to old females (0.31), suggesting that males decline in competitive ability as they age. Nonetheless males, but not females, showed an apparent increase in breeding success over the entire lifetime, a possible indication that very old males make a terminal investment in reproductive output at the cost of survival. [ABSTRACT FROM AUTHOR]

We recorded for the first time the Common Loon (Gavia immer) on the coast of Oaxaca state, Mexico. We observed an over-summering individual bird at the beach known as Playa Azul (07/13/2014), in the municipality of Salina Cruz, Oaxaca. The individual showed a non-breeding plumage, and has been observed in good condition. Due to the scarcity or lack of records by an irregular observation effort, the region could be considered as the natural distribution limit for the species. [ABSTRACT FROM AUTHOR]

We captured 93 wintering adult and subadult Common Loons ( Gavia immer ) in coastal Louisiana from 2011 to 2015 following the Deepwater Horizon oil spill. We tested blood samples for exposure to polycyclic aromatic hydrocarbons (PAHs) and measured physiological variables including hematocrit, hemoglobin and total blood protein. PAH concentrations in loon blood differed from year to year and by age class. High PAH concentrations were significantly related to lower body masses in both adult and subadult birds and higher serum protein levels in adults only. PAH concentrations had marginal relations with both hematocrit and hemoglobin levels. The types of PAHs detected also underwent a major shift over time. The PAHs detected in 2011, 2012, and 2015 were primarily low molecular weight (three carbon rings); however, in 2013, most detected PAHs were high molecular weight (four carbon rings). It is unclear what events led to the increase in PAH concentrations and the shift in type of PAHs over time. [ABSTRACT FROM AUTHOR]

Based on field observations from March 2003 to January 2015 in the Alvarado Wetlands (aw), we present records of 10 bird species found outside of its distribution or despite having their potential distribution in the Alvarado Wetlands, there is a lack or there are a few records in that area. The Common Loon (Gavia immer) and the Masked Booby (Sula dactylatra) were recorded for the first time; the Surf Scoter (Melanitta perspicillata), the Bonaparte's Gull (Chroicocephalus philadelphia), the Ruby-crowned Kinglet (Regulus calendula), and the Prairie Warbler (Setophaga discolor) were recorded for the second time in the area. We also include the Red-legged Honeycreeper (Cyanerpes cyaneus) and the Scarlet Tanager (Piranga olivacea), which are rare in the area, and the Lesser Goldfinch (Spinus psaltria) and the Eurasian Collared-Dove (Streptopelia decaocto), species that have recently expanded their distribution. These records can be attributed to different causes: migratory behaviour, weather, human introduction, habitat modification, and an increased monitoring effort. [ABSTRACT FROM AUTHOR]

Common Loons (Gavia immer) appear to use physical habitat, human disturbance, and social cues when selecting territories; however, recent loon habitat models suggest that the importance of each of these cues may vary depending on population density. We conducted loon detection surveys on lakes (n = 42) in the Lower Peninsula of Michigan, USA, during 2007-2008, and developed territory occupancy and nest success models. We found that occupancy was positively associated with lake area and the presence of islands, whereas road density (human disturbance) and the number of loon pairs within 10 km (social cue) were not important predictors of occupancy. Similarly, loon nest success was positively associated with lake area and the presence of islands. Both models performed well when applied to an independent dataset of 85 lakes (AUC = 0.743 and 0.724, respectively), indicating that these models could be used for identifying suitable habitat during conservation efforts. Our results suggest that managers should first focus efforts on maintaining or creating nesting islands on lakes, and then assess regional loon occupancy rates once physical habitat conditions are met. Comparing our results with recent loon habitat models, we suggest that social cue covariates are most important at low population densities, whereas physical habitat covariates are dominant predictors of occupancy at higher population densities of loons. Loon response to human disturbance appears to be location-specific, depending on the level of human development around lakes and local conservation efforts, particularly the provision of artificial nest platforms. [ABSTRACT FROM AUTHOR]

In many avian species, breeding site fidelity has been more thoroughly investigated than winter site fidelity, yet the latter may have a greater impact on survivorship. The Common Loon (Gavia immer) is an example of a species whose breeding site fidelity has been well established, but whether it exhibits winter site fidelity remains unknown. Because Common Loons primarily winter in marine waters off coastal shores, winter site fidelity has been challenging to document. We investigated winter site fidelity in Common Loons across North America using satellite transmitters, recaptures, and resightings of previously color-marked individuals. Color-marked adults returned in consecutive years to the same coastal wintering locations in California, Washington, Louisiana, Maryland, and Massachusetts, USA. We estimated adult annual apparent survival as 77% (0.48-0.93) and adult winter site fidelity as 85% (0.35-0.98). This finding has important conservation implications in the aftermath of recent marine oil spills; if Common Loons return to the same contaminated wintering areas annually, decreased fitness and survivorship could result in population-level effects. [ABSTRACT FROM AUTHOR]

In many territorial breeders, conspecifics that intrude during the chick-rearing period pose a threat to survival of young. Defense of young from intruders is costly to parents, so it is likely that intense selective pressure has shaped chick defense so as to maximize parental fitness. We simulated territorial intrusion by exposing adult common loons Gavia immer and their chicks to a decoy and used mixed models to investigate responses. We tested two hypotheses: 1) the value hypothesis, which holds that parents should defend large broods of off spring more strongly because of the greater potential fitness benefits they offer, and 2) the vulnerability hypothesis, which predicts vigorous defense of young off spring, whose small size and limited mobility render them vulnerable to sudden attacks from intruders that approach under water. Under natural conditions, parents spent over 80% of their time within 20 m of chicks younger than two weeks ('young chicks') but 66% or less of their time close to chicks four weeks or older ('old chicks'). Parents of young chicks associated less with the decoy but yodelled and penguin danced more during decoy trials than did parents of old chicks, supporting the conclusion that the parents protected young chicks not by engaging intruders directly but by remaining close to chicks and using vocalization and display to keep intruders at a distance. While these findings lent clear support to the vulnerability hypothesis, the value hypothesis too was supported, as males with two-chick broods were almost three times more likely to yodel than males with singleton chicks. Age of parents was not associated with any aspect of chick defense, but the paucity of known-aged parents in the oldest age classes makes future investigation of age effects warranted. [ABSTRACT FROM AUTHOR]

A field study was conducted in Wisconsin (USA) to characterize in ovo mercury (Hg) exposure in common loons ( Gavia immer). Total Hg mass fractions ranged from 0.17 µg/g to 1.23 µg/g wet weight in eggs collected from nests on lakes representing a wide range of pH (5.0-8.1) and were modeled as a function of maternal loon Hg exposure and egg laying order. Blood total Hg mass fractions in a sample of loon chicks ranged from 0.84 µg/g to 3.86 µg/g wet weight at hatch. Factors other than mercury exposure that may have persistent consequences on development of chicks from eggs collected on low-pH lakes (i.e., egg selenium, calcium, and fatty acid mass fractions) do not seem to be contributing to reported differences in loon chick quality as a function of lake pH. However, it was observed that adult male loons holding territories on neutral-pH lakes were larger on average than those occupying territories on low-pH lakes. Differences in adult body size of common loons holding territories on neutral-versus low-pH lakes may have genetic implications for differences in lake-source-related quality (i.e., size) in chicks. The tendency for high in ovo Hg exposure and smaller adult male size to co-occur in low-pH lakes complicates the interpretation of the relative contributions of each to resulting chick quality. Environ Toxicol Chem 2015;34:1870-1880. © 2015 SETAC [ABSTRACT FROM AUTHOR]

While wind power is a promising source of renewable energy, there have been persistent questions about the safety of migrating birds in the presence of wind farms. In this paper we develop a framework that allows us to consider the costs and benefits of a very simple strategy: curtailing (turning off) the turbines during high-risk periods for endangered species. We develop a model that allows us to find the lowest financial cost strategy (where cost is represented in dollars) for the curtailing operation, given a specific goal for bird mortality reduction. We apply the model to a specific case study: the proposed Cape Wind project and the vulnerability of the common loon ( Gavia immer ), during one month of the migratory season. We calculate probability distributions over energy produced, price, and revenue to the wind farm, as well as over the numbers of loon mortality, and perform an uncertainty analysis. As an example, we find that with the goal of reducing 10% of the expected bird deaths during the month of March, the cost per bird averages $170, using the most cost effective curtailment strategy. [ABSTRACT FROM AUTHOR]

Biologists now use a variety of survey platforms to assess the spatial distribution and abundance of marine birds, yet few attempts have been made to integrate data from multiple survey platforms to improve model accuracy or precision. We used density surface models (DSMs) to incorporate data from two survey platforms to predict the distribution and abundance of a diving marine bird, the Common Loon (Govia immer). We conducted strip transect surveys from a multiengine, fixed-wing aircraft and line surveys from a 28 m ship during winter 2009-2010 in a 3,800 km2 study area off the coast of Rhode Island, USA. We accounted for imperfect detection and availability bias due to Common Loon diving behavior. We incorporated spatially explicit environmental covariates (water depth and latitude) to provide predictions of the spatial distribution and abundance of wintering Common Loons. The combined-platform DSM estimated the highest Common Loon densities (>20 individuals km-2) in nearshore waters <35 m deep, with an average daily abundance of 5,538 (95% Cl = 4,726-6,489) individuals in the study area. The combined-platform model offered substantial improvement in the precision of abundance estimates from the ship-platform model, and modest improvement in the precision of the aerial-platform model. The combined model had relatively low predictive power, which previous research indicates is primarily a consequence of the dynamic marine environment. We show that the DSM approach presents a flexible framework for developing spatially explicit models of a marine bird from different survey protocols. [ABSTRACT FROM AUTHOR]

Registramos observaciones sobresalientes de aves en el sur del estado de Veracruz. Se reporta la tercera localidad donde se ha registrado la polluela pechigris (Laterallu sexilis) para el país, el primer registro para el estado del rascón cuello rufo (Aramides axillaris), el segundo registro de colimbo mayor (Gavia immer) para el sur del estado, así como el registro de una pareja de hocofaisanes (Crax rubra) en el área de manglar de Sontecomapan. [ABSTRACT FROM AUTHOR]

ABSTRACT Water-level management is widespread and illustrates how contemporary climate can interact directly and indirectly with numerous biological and abiotic factors to influence reproductive success of wildlife species. We studied common loons, an iconic waterbird sensitive to timing and magnitude of water-level changes during the breeding season, using a before-after-control-impact design on large lakes in Voyageurs National Park (Minnesota, USA), to assess the effect of anthropogenic changes in hydroregime on their nesting success and productivity. We examined multiple competing a priori hypotheses in an information-theoretic framework, and predicted that magnitude of changes in loon productivity would be greater in the Namakan Reservoir, where water-level management was altered to mimic a more natural hydroregime, than in Rainy Lake, where management remained relatively unchanged. We determined outcomes from 278 nests during 2004-2006 by performing boat-based visits every 3-5 days, and measuring hydrologic, vegetative, and microtopographic covariates. Relative to comparably collected data for 260 total loon pairs during 1983-1986, productivity (chicks hatched/territorial pair) increased 95% in the Namakan Reservoir between the 2 time periods. Nest success declined in both lakes over the 2 study periods but less so in the Namakan Reservoir than in Rainy Lake. Flooding was a primary cause of nest failures (though second nests were less likely to flood). Nest predation appears to have increased considerably between the 2 study periods. Top-ranked models suggested that timing of nest initiation, probability of nest flooding, probability of nest stranding, and probability of nest success were each related to 2-4 factors, including date of initiation, timing of initiation relative to peak water levels, changes in the elevation of the nest edge, maximum water-level change between initiation and peak water levels, and maximum water-level change between initiation and nest outcome. The top model for all variables except stranding each garnered ≥82% of total model weight. Results demonstrate that water-level management can be altered to benefit productivity of common loons. However, nuanced interactions between land-use change, invasive species, human development, recreation, climate change, and recovery of top predators may often complicate both management decisions and interpretation of water-level impacts on wildlife. © 2013 The Wildlife Society. [ABSTRACT FROM AUTHOR]