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At least 1,711 records · Page 95Linked to original sources
USGS2021

Revealing migratory path, important stopovers and non-breeding areas of a boreal songbird in steep decline

The Olive-sided Flycatcher (Contopus cooperi) is a steeply declining aerial insectivore with one of the longest migrations of any North American passerine. We deployed light-level geolocators and archival GPS tags on breeders in boreal Alaska to determine migratory routes, important stopovers and non-breeding locations. Data from 16 individuals revealed a median 23,555 km annual journey (range: 19,387, 27,292 km) over 95 days (range: 83, 139 days) with wintering occurring in three regions of South America (NW Colombia/Ecuador, central Peru and W Brazil/S Peru). We developed a new method to identify “Important Stopovers” by quantifying intensity of use (a function of bird numbers and stop durations) along migratory routes. We identified 13 Important Stopovers that accounted for ~66% of the annual migratory period, suggestive of refueling activities. Some sites coincided with key areas previously identified for other Neotropi- cal-Nearctic migrants. Percent land “protected” at Impor- tant Stopovers, as defined by IUCN, ranged from 3.8% to 49.3% (mean [95% CI]: 17.3% [9.6, 25.0]). Total migration speed did not differ by season (median: 255 km day-1, range: 182, 295km day-1), despite greater spring travel dis- tances. Birds with longer non-breeding periods, however, migrated north faster. Climate-driven mismatches in migratory timing may be less of a concern for western than for eastern flycatcher populations, given recent con- generic analyses (C. sordidulus, C. virens). However, accel- erated high-latitude changes, may nonetheless impact boreal breeders.

Alaska↗
USGS2007

Potential hazards of environmental contaminants to avifauna residing in the Chesapeake Bay estuary

A search of the Contaminant Exposure and Effects-Terrestrial Vertebrates (CEE-TV) database revealed that 70% of the 839 Chesapeake Bay records deal with avian species. Studies conducted on waterbirds in the past 15 years indicate that organochlorine contaminants have declined in eggs and tissues, although p,p'-DDE, total polychlorinated biphenyls (PCBs) and coplanar PCB congeners may still exert sublethal and reproductive effects in some locations. There have been numerous reports of avian die-off events related to organophosphorus and carbamate pesticides. More contemporary contaminants (e.g., alkylphenols, ethoxylates, perfluorinated compounds, polybrominated diphenyl ethers) are detectable in bird eggs in the most industrialized portions of the Bay, but interpretation of these data is difficult because adverse effect levels are incompletely known for birds. Two moderaterized oil spills resulted in the death of several hundred birds, and about 500 smaller spill events occur annually in the watershed. With the exception of lead, concentrations of cadmium, mercury, and selenium in eggs and tissues appear to be below toxic thresholds for waterbirds. Fishing tackle and discarded plastics, that can entangle and kill young and adults, are prevalent in nests in some Bay tributaries. It is apparent that exposure and potential effects of several classes of contaminants (e.g., dioxins, dibenzofurans, rodenticides, pharmaceuticals, personal care products, lead shot, and some metals) have not been systematically examined in the past 15 years, highlighting the need for toxicological evaluation of birds found dead, and perhaps an avian ecotoxicological monitoring program. Although oil spills, spent lead shot, some pesticides, and industrial pollutants occasionally harm Chesapeake avifauna, contaminants no longer evoke the population level effects that were observed in Ospreys (Pandion haliaetus) and Bald Eagles (Haliaeetus leucocephalus) through the 1970s.

Waterbirds↗
USGS2019

Trends in landbird density at two national parks in fragmented, mixed-use landscapes of the Pacific Northwest

National parks play a key role in conserving species by providing landscapes where threats from anthropogenic disturbance are reduced. In a recent study of 3 large wilderness parks in the Pacific Northwest, nearly all landbird species were found to be stable or increasing. Nonetheless, contemporary results from the Breeding Bird Survey and mark-recapture studies fuel concerns that some landbirds in the Pacific Northwest are trending in sync with many North America species in widespread decline. Although landbird populations might be thriving in large parks with extensive old-growth forest, those in smaller parks with less intact wilderness and higher ratios of edge-to-interior habitat might reflect the stressors inherent in more human-dominated landscapes. We conducted landbird point-count surveys from 2005 to 2016 in 2 national historical parks situated in the more human-dominated landscapes of this region, San Juan Island National Historical Park and Lewis and Clark National Historical Park. Established primarily to protect cultural resources, these parks lack old-growth forest and consist of relatively small parcels embedded in fragmented, multi-use landscapes. Here, we apply recent developments in point-count analysis to estimate trends in population density for 50 landbird species commonly detected in these small parks, including lagged effects of precipitation and temperature on the annual density of each species, and effects of survey conditions on species detection. All but 3 species exhibited stable densities in both parks, and more than half of the populations analyzed clearly increased in density over the study period. Notable exceptions were single-park declines in Olive-sided Flycatcher ( Contopus cooperi ), Northern Flicker ( Colaptes anratus ), and Hutton's Vireo ( Vireo huttoni ). Annual variation in population density was often related to climate, with generally positive responses to a recent deficit in annual precipitation-as-snow, and more variable responses to higher mean spring temperature. These results reinforce trends estimated for 3 large national parks in the Pacific Northwest, suggesting recent stability of landbird populations in parks of this region, independent of park size or setting.

Northwestern Naturalist↗
USGS2023

Guide for benthic invertebrate studies in support of Natural Resource Damage Assessment and Restoration

This guide is intended to assist with characterizing injury to freshwater benthic macroinvertebrates (BMIs) in Natural Resource Damage Assessment and Restoration (NRDAR) cases. The contents are narrowly focused on insects, crustaceans, snails, and other invertebrate fauna that are typically considered part of BMI communities and are not intended to address studies of injury to larger benthic taxa such as freshwater mussels, crayfish, or benthic fishes or amphibians. Although some percentage of the community functions as predators, BMIs are predominantly primary consumers (for example, scrapers, shredders, and filterer/gatherer feeding groups) that play an essential role in converting carbon and nitrogen from plant tissues into animal biomass for higher-order consumers, especially in flowing waters. Aquatic contaminants can disrupt the quantity and quality of energy transferred (ecosystem function) by reducing invertebrate biomass and diversity. Additionally, the accumulation of toxic residues in invertebrate tissues may be a source of exposure leading to adverse effects in higher trophic levels. The goal of NRDAR BMI assessments is to establish direct linkages of contaminant exposure to injuries reflected by changes in community structure (for example, reduced density and taxa richness) or by effects at the individual population level (for example, survival, growth, and reproduction). BMIs are infrequently the U.S. Department of Interior (DOI)-managed resource in a NRDAR case, with managed resources more frequently including migratory birds, fish, or other insectivorous vertebrates. Therefore, it is critical to have clearly defined objectives for evaluating BMIs and an understanding of how invertebrate data relate to the quantification of injuries to the DOI-managed resource. This guide is intended to assist decisions on whether or not to proceed with BMI studies, use of existing information and data for screening purposes, and what types of studies can support a BMI-injury determination. This document is intended to provide general considerations and best practices for assessing BMIs. Relevant guidance and references are listed throughout the report as sources for specific methods and analysis.

Open-File Report↗
USGS2006

An efficient method of capturing Painted Buntings and other small granivorous passerines

To study survival in the eastern breeding population of the Painted Bunting (Passerina ciris), I developed a technique to capture a large sample of buntings for color marking with leg-bands. This involved the use of bird feeders and an array of three short mist nets located at 40 sites in four states, each site meeting five specific criteria. In five years of mist netting (1999-2003), 4174 captures (including recaptures) of Painted Buntings were made in 3393 net-hours or 123 captures per 100 net-hours. The technique proved to be effective and efficient, and may have broad application for capturing large numbers of small granivorous passerines.

North American Bird Bander↗
USGS1985

Organophosphate insecticide (famphur) topically applied to cattle kills magpies and hawks

A systematic field study of a black-billed magpie ( Pica pica ) population revealed that magpies and red-tailed hawks ( Buteo jamaicensis ) were killed by famphur (=famophos, Warbex®) used as a pouron to control cattle warbles ( Hypoderma sp.). Magpie mortality began on treatment day and continued for more than 3 months (38 found dead); mortality peaked between Day 5 and Day 13. Estimates of magpie density (based on transects) decreased in both the control and treatment areas, but the decrease was greater in the treatment area. A red-tailed hawk found dead on Day 10 had eaten a famphur-contaminated magpie. Another red-tailed hawk was found alive but immobilized, and a third died outside the study area. Brain cholinesterase (ChE) activity was 70-92% depressed in all dead birds examined; famphur residues were detected in all 17 magpies and the 2 hawks analyzed. The amount of famphur obtained by the dead magpies was estimated at 5.2-6.1 mg/kg (based on residue concentrations in the gizzard), which was above the acute oral LD50 for several bird species. The cow hair portion (12%) of the pooled gizzard contents from 13 other dead magpies produced extremely high famphur residues (4,600 ppm). The residues persisted on cattle hair for more than 90 days post-treatment. Magpie populations in the far western states declined between 1968 and 1979, which corresponds with widespread use of famphur, although other factors may be involved.

Washington↗
USGS2024

Passive acoustic monitoring and convolutional neural networks facilitate high-resolution and broadscale monitoring of a threatened species

Population monitoring is an essential component of biodiversity conservation and management, but low detection probabilities for rare and/or cryptic species makes estimating abundance and occupancy challenging. Passive acoustic monitoring combined with machine learning algorithms represents a potential path forward to effectively and efficiently monitor the occurrence of rare vocalizing species across entire forest landscapes. Our objectives were to develop and implement a convolutional neural network (PNW-Cnet) to identify vocalizations of a rare and threatened forest nesting bird species – the marbled murrelet ( Brachyramphus marmoratus ) – in the Pacific Northwest, U.S.A., 2018–2021. We used PNW-Cnet predictions from broadscale passive acoustic monitoring data to examine spatiotemporal patterns in the distribution of murrelets. PNW-Cnet showed sufficiently high prediction accuracy (overall precision > 0.9) to enable broadscale population monitoring. Spatiotemporal analysis showed that annual peak murrelet call abundance occurs in ordinal weeks 28–32 (late July–Mid August) but this varied by study area. The greatest number of detections typically occurred in the Olympic Peninsula and Oregon Coast Range where late-successional forest dominates and nearer to ocean habitats. We demonstrate that passive acoustic monitoring can be used to understand intensity of use across broad scales for a rare and cryptic species in addition to the typical detection/non-detection data that are often collected. Passive acoustic monitoring combined with PNW-Cnet offers considerable promise for species distribution modeling and long-term population monitoring for rare species.

Oregon, Washington↗
USGS1986

Marine birds

In this chapter we review existing knowledge of marine birds in the Gulf of Alaska. Three estuarine systems in the Gulf provide critical habitat for migratory shorebirds and waterfowl: 1) the Stikine River Delta, 2) Cook Inlet, and 3) the Copper River Delta. Over 20 million waterbirds are estimated to use the latter system during spring migration. Western sandpipers, dunlin, and northern pintails numerically dominate this migration. Breeding populations of shorebirds and waterfowl in the Gulf are small compared with those elsewhere in Alaska. Of those Gulf regions suitable for nesting waterfowl and shorebirds, the Copper River Delta is the most important. Species diversity and the number of shorebirds wintering in the Gulf are low; however, water- fowl wintering in the Gulf number at least in the low millions. These birds concentrated in sheltered, near-shore regions where their epibenthic and infaunal prey are accessible. Over nine million seabirds (twenty-six species) nest in the Gulf of Alaska at more than 800 sites. Seabird productivity varies markedly. Food availability seems to have a large influence on reproductive success, especially for surface-feeding species such as the black-legged kittiwake. Seabird densities are highest over shelf and shelf-break habitats during spring migration and in summer. Sooty and short-tailed shearwaters dominate the pelagic avifauna both numerically and in terms of biomass. Seabird densities are generally lower in winter than in summer as a result of both a southward migration of some species and offshore dispersal of others. A variety of prey species are used by seabirds in the Gulf; of these, capelin, sand lance, and euphausiids are of greatest importance. Trophically, seabirds in the Gulf range from near primary con- sumers to third-order carnivores, ingesting an estimated 1,120,000 mt during the 120-day summer period.

Alaska↗
USGS1999

Boreal partners in flight: Working together to build a regional research and monitoring program

Boreal regions of western North America regularly support breeding populations of 130 species of landbirds, including 68 Nearctic-Neotropical migrants. Primary conservation concerns within the region include increased timber harvesting, insect outbreaks, fire suppression, mining, impacts of military training activities, urbanization, and recreational activities. Under auspices of Partners in Flight, biologists, land and resource managers, and conservationists from Alaska and western Canada have combined efforts to develop a regional research and monitoring program for landbirds. An experimental monitoring program has been under way during the past four years to test the relative statistical power and cost-effectiveness of various monitoring methods in Alaska. Joint efforts currently include the Alaska Checklist Project on National Wildlife Refuges, 75 Breeding Bird Surveys along the road system, 122 Off-road Point Count routes, 27 Monitoring Avian Productivity and Survivorship banding sites, and 8 migration banding stations. The ultimate goal is to design a comprehensive monitoring program that is sensitive to changes in population size, survival rates, and productivity, but robust enough to accommodate logistical constraints that arise when working in vast, roadless areas with limited funds and staff. Primary challenges that must be faced to assure the long-term future of such a program are obtaining long-term commitment from resource agencies in the region, integrating this program with other national and regional programs that address those species and habitats that are inadequately monitored by established techniques, and developing cooperative research, monitoring, and management programs at the landscape level.

Alaska↗
USGS2019

Ecosystem scale loss of grazing habitat impacted by abundance of dominant herbivores

Grazing lawns, patches of grazing tolerant plants with high nutrient value, provide important habitat for herbivores, and changes in abundance can impact herbivore populations. Grazing lawns are maintained in quality and quantity by repeated grazing and are a result of a positive feedback since the availability of grazing lawn can increase herbivore populations and increased herbivore populations can result in an increase in grazing lawn extent. We sampled aerial imagery from a long-term dataset (>20 yrs) at an internationally important breeding area for avian herbivores to model changes in grazing lawn abundance over time and identify the possible factors impacting those changes, including numbers of breeding birds, their primary predator, and spring phenology. Our data suggests that avian herbivores and their predators likely exert strong impacts on plant communities and may drive vegetation abundance. Decreases in the number of herbivore nests in our study coincided with an almost complete lack of grazing lawn in the mid-2000s. Any factors dictating the amount of grazing lawn available for avian herbivores could strongly influence breeding success and the maximum size of these populations. Our results demonstrate the importance of studying complex interactions among predators, herbivores and plants, and population moderation by both bottom-up and top-down processes.

Ecosphere↗
USGS2023

Demographics and gross pathology of scoters and scaups killed by the Cosco Busan oil spill in California

Unusual wildlife mortality events provide a unique opportunity to collect information on demographics, disease, and body condition in affected wildlife, which may be useful for informing oil spill damage assessments and future spill responses. In November 2007, the Cosco Busan Oil Spill occurred in San Francisco Bay, California, a globally important wintering area for waterfowl. The spill resulted in the mortality of scoters Melanitta spp. and scaups Aythya spp., species that have declined significantly over recent decades. We examined the demography (sex and age ratios) and prevalence of grossly apparent disease (acanthocephalan parasite infection and mycotic disease) in 288 Surf Scoters M. perspicillata , White-winged Scoters M. deglandi , Greater Scaup A. marila , and Lesser Scaup A. affinis killed in the oil spill. The proportions of females and juveniles in examined Surf Scoters was unexpectedly high (0.98:1, females:males, 0.73:1 juveniles:adults) for this species with normally strong male- and adult-biased populations. This disproportionate mortality of female Surf Scoters could result in a greater population impact on this female-limited species, suggesting a mechanism for steep declines in San Francisco Bay scoter numbers in the years after the Cosco Busan oil spill. Significantly greater rates of acanthocephalan infection in juvenile vs. adult Surf Scoters indicated a possible interaction between acanthocephalan parasitism and juvenile-biased mortality in our sample. Birds that died during rehabilitation had significantly greater rates of mycotic disease (10% infected) than birds found dead in the field (3%), indicating that infections began or worsened during rehabilitation. Greater Scaup had proportionally greater rates of infection with mycotic disease (26% of individuals) than other species, indicating that they may be particularly susceptible to the disease. We encourage the documentation of demographics and disease as a regular part of future responses to oil spills, or other mortality events, to gain insight into population impacts and improve rehabilitation efforts of affected populations.

California↗
USGS2016

Wind energy development: Methods to assess bird and bat fatality rates post-construction

Monitoring fatalities at wind energy facilities after they have been constructed can provide valuable information regarding impacts of wind power development on wildlife. The objective of this monitoring is to estimate abundance of a super-population of carcasses that entered the area within a designated period of time. By definition, the population is not closed and carcasses can enter as they are killed through collision with turbines, and leave as they are removed by scavengers or decompose to a point where they are not recognizable. In addition, the population is not inherently mobile, but can only change location through some external force. A focus on number of animal carcasses comprising the super-population, combined with peculiar traits that resist classic assumptions, distinguish fatality estimation at wind-power facilities from more classic abundance estimates that can be addressed through mark-recapture techniques or other well-known abundance estimators. We review the available methods to estimate the super-population of carcasses at wind power facilities. We discuss the role of these estimates in determining appropriate levels of minimization and mitigation of impacts to individual species of concern. We discuss the potential to extrapolate these measurements to reflect the cumulative effect of the industry on individual species. Finally, we suggest avenues of research needed to strengthen our understanding of the effect wind power development has, and might have in the future, on wildlife on this continent and worldwide.

Human-Wildlife Interactions↗
USGS2022

Prioritizing habitats based on abundance and distribution of molting waterfowl in the Teshekpuk Lake Special Area of the National Petroleum Reserve, Alaska

The National Petroleum Reserve in Alaska (NPR-A) encompasses more than 9.5 million hectares of federally managed land on the Arctic Coastal Plain of northern Alaska, where it supports a diversity of wildlife, including millions of migratory birds. Within the NPR-A, Teshekpuk Lake and the surrounding area provide important habitat for migratory birds and this area has been designated by the Bureau of Land Management as the Teshekpuk Lake Special Area (TLSA) because numerous waterfowl species use the area for breeding and molting. Our goal was to provide a mechanism for land managers to assess relative value of areas for molting waterfowl. This approach was based on the population densities of Pacific black brant ( Branta bernicla nigricans ) and cackling geese ( Branta hutchinsii ) and pre-defined thresholds for the minimum fraction of the population contained within selected areas. Prioritizations were based on long-term records of population density combined with global-positioning system data to reveal small-scale patterns of habitat use. The highest population density of the Pacific black brant was found along the Beaufort Sea coast on the eastern edge of the study area, whereas cackling geese were somewhat more widely distributed. Depending on the criteria used for prioritization and width of protective buffers placed around selected units, 52–85% of the Goose Molting Area was identified as high-priority area. The effectiveness of this approach to protection of molting birds assumes that buffers around high value units are wide enough to provide adequate protection from disturbance related to oil and gas development.

Alaska↗
USGS2022

Optimizing surveys of fall-staging geese using aerial imagery and automated counting

Ocular aerial surveys allow efficient coverage of large areas and can be used to monitor abundance and distribution of wild populations. However, uncertainty around resulting population estimates can be large due to difficulty in visually identifying and counting animals from aircraft, as well as logistical challenges in estimating detection probabilities. Photographic aerial surveys can mitigate these challenges and can allow flight at higher altitudes to minimize disturbance of birds and improve safety for surveyors. We evaluated a photographic aerial survey that incorporated a systematic sampling design with automated photo capture and processing for fall-staging geese at Izembek Lagoon, Alaska, in 2017–2019. Ocular aerial surveys have been completed at Izembek Lagoon for >40 years. For the new photo survey, we used a commercial system to automatically trigger cameras at preset points. We then applied a machine-learning algorithm trained to automatically identify and count geese in our photos, manually corrected those counts, and quantified the algorithm's accuracy. We translated corrected counts into density and extrapolated mean density across the entire lagoon to estimate total population size for Pacific brant ( Branta bernicla ) and cackling geese ( B. hutchinsii ). The automated algorithm undercounted geese, but successfully identified the small subset of photos containing geese. Manual correction was therefore needed only for photos automatically identified as containing geese, allowing substantial reduction of workload. Manually-corrected, photo-based estimates of Pacific brant and cackling goose population sizes were larger and more precise than ocular estimates in all 3 years. To reduce costs with little penalty for variance around population estimates, the photographic survey design could be optimized by reducing the number of transects to ~67% of the current number while still manually correcting all photos in which the automated algorithm detected geese. Further years of both ocular and photo surveys would be needed to calibrate the photo estimates against the >40-year timeseries of the ocular survey, after which the photo series could successfully guide management of Pacific brant. As technologies continue to advance, we expect photographic surveys with automated counting to be easily implemented and advantageous to many monitoring programs.

Alaska↗
USGS2001

What caused the population decline of the Bridled White-eye on Rota, Mariana Islands?

The Bridled White-eye ( Zosterops conspicillatus rotensis ) was Once thought to be common and widespread on Rota, Commonwealth of the Northern Mariana Islands, but is now restricted to several patches of native limestone forest in and adjacent to the Sabana region. Surveys conducted in 1990 indicated that the population had declined by 87% between 1982 and 1990 for unknown reasons. The low density and restricted habitat association of the Bridled White-eye on Rota contrasts with the situation on Saipan, Tinian, Agiguan, and formerly on Guam, where the Bridled White-eye is the most common forest bird and occurs at all elevations and in all habitat types. We surveyed the entire range of the Rota Bridled White-eye in 1996 to estimate its current numbers and distribution. We also reviewed existing information on the white-eye and evaluated potential causes of its decline, including predation by Black Drongos ( Dicrurus macrocercus ), rats ( Rattus spp.), and the brown tree snake Boiga irregularis ); pesticides; avian disease; and habitat loss and alteration. We found that 94% of the extant population of 1,165 white-eyes on Rota was restricted to four patches of old-growth, native limestone forest covering only 259 ha. We believe that the population decline and current localized distribution is primarily a result of habitat changes due to agricultural development and typhoons, but the absence of white-eyes from several stands of native forest above 200 m remains unexplained. The Rota white-eye may be a different species from white-eyes found on Saipan, Tinian, Agiguan, and Guam, with different habitat preferences.

Rota↗
USGS2016

Experience drives innovation of new migration patterns of whooping cranes in response to global change

Anthropogenic changes in climate and land use are driving changes in migration patterns of birds worldwide. Spatial changes in migration have been related to long-term temperature trends, but the intrinsic mechanisms by which migratory species adapt to environmental change remain largely unexplored. We show that, for a long-lived social species, older birds with more experience are critical for innovating new migration behaviours. Groups containing older, more experienced individuals establish new overwintering sites closer to the breeding grounds, leading to a rapid population-level shift in migration patterns. Furthermore, these new overwintering sites are in areas where changes in climate have increased temperatures and where food availability from agriculture is high, creating favourable conditions for overwintering. Our results reveal that the age structure of populations is critical for the behavioural mechanisms that allow species to adapt to global change, particularly for long-lived animals, where changes in behaviour can occur faster than evolution.

Nature Communications↗
USGS2019

Functional divergence of thyrotropin beta-subunit paralogs gives new insights into salmon smoltification metamorphosis

Smoltification is a metamorphic event in salmon life history, which initiates downstream migration and pre-adapts juvenile salmon for seawater entry. While a number of reports concern thyroid hormones and smoltification, few and inconclusive studies have addressed the potential role of thyrotropin (TSH). TSH is composed of a α-subunit common to gonadotropins, and a β-subunit conferring hormone specificity. We report the presence and functional divergence of duplicated TSH β-subunit paralogs (tshβa and tshβb) in Atlantic salmon. Phylogeny and synteny analyses allowed us to infer that they originated from teleost-specific whole genome duplication. Expression profiles of both paralogs in the pituitary were measured by qPCR throughout smoltification in Atlantic salmon from the endangered Loire-Allier population raised at the Conservatoire National du Saumon Sauvage. This revealed a striking peak of tshβb expression in April, concomitant with downstream migration initiation, while tshβa expression remained relatively constant. In situ hybridization showed two distinct pituitary cell populations, tshβa cells in the anterior adenohypophysis, and tshβb cells near to the pituitary stalk, a location comparable to the pars tuberalis TSH cells involved in seasonal physiology and behaviour in birds and mammals. Functional divergence of tshβ paralogs in Atlantic salmon supports a specific role of tshβb in smoltification.

Scientific Reports↗
USGS2017

Time within reproductive season, but not age or inbreeding coefficient, influences seminal and sperm quality in the whooping crane (Grus americana)

All living whooping cranes ( Grus americana ) are descended from 16 or fewer birds that remained alive in the early 1940s, a bottleneck that puts the species at potential risk for inbreeding depression. Although AI is commonly used in the management of the captive population of this species, little is known about seminal traits or factors affecting sperm quality in the whooping crane. In the present study, semen samples were collected from 29 adult males (age 3–27 years) during the early (March), mid (April) and late (May) breeding season over 2 consecutive years. The effects of donor age, time within reproductive season and level of inbreeding on seminal characteristics were analysed using regression and information–theoretic model selection. Only time within reproductive season significantly affected seminal traits, with total numbers of spermatozoa and proportions of pleiomorphisms increasing across the season. We conclude that, even with a highly restricted number of founders, there is no discernible influence of inbreeding (at the levels described) on sperm output or quality. Furthermore, although there is variance in seminal quality, the whooping crane produces significant numbers of motile spermatozoa throughout the breeding season, similar to values reported for the greater sandhill crane ( Grus canadensis tabida ).

Reproduction, Fertility and Development↗