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At least 595 records · Page 33Linked to original sources
USGS2020

Direct and indirect effects of a keystone engineer on a shrubland-prairie food web

Keystone engineers are critical drivers of biodiversity throughout ecosystems worldwide. Within the North American Great Plains, the black‐tailed prairie dog is an imperiled ecosystem engineer and keystone species with well‐documented impacts on the flora and fauna of rangeland systems. However, because this species affects ecosystem structure and function in myriad ways (i.e., as a consumer, a prey resource, and a disturbance vector), it is unclear which effects are most impactful for any given prairie dog associate. We applied structural equation models (SEM) to disentangle direct and indirect effects of prairie dogs on multiple trophic levels (vegetation, arthropods, and birds) in the Thunder Basin National Grassland. Arthropods did not show any direct response to prairie dog occupation, but multiple bird species and vegetation parameters were directly affected. Surprisingly, the direct impact of prairie dogs on colony‐associated avifauna (Horned Lark [ Eremophila alpestris ] and Mountain Plover [ Charadrius montanus ]) had greater support than a mediated effect via vegetation structure, indicating that prairie dog disturbance may be greater than the sum of its parts in terms of impacts on localized vegetation structure. Overall, our models point to a combination of direct and indirect impacts of prairie dogs on associated vegetation, arthropods, and avifauna. The variation in these impacts highlights the importance of examining the various impacts of keystone engineers, as well as highlighting the diverse ways that black‐tailed prairie dogs are critical for the conservation of associated species.

Wyoming↗
USGS2022

Proceedings of the Highly Pathogenic Avian Influenza and Wild Birds Webinar Series, August 2–5, 2021

In light of ongoing and geographically widespread highly pathogenic avian influenza (HPAI) outbreaks in wild birds throughout much of Eurasia during 2020–21, the Interagency Steering Committee for Avian Influenza Surveillance in Wild Migratory Birds disseminated an informational memorandum in January 2021 to highlight the need for enhanced surveillance and heightened awareness in North America. This was followed by coordination of this August 2021 international HPAI webinar series facilitated by the U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) Veterinary Services Training Program. In addition to heightening awareness, the webinars provided an opportunity for information exchange and facilitated virtual discussions between Federal, State, academic, and international partners on the ongoing Eurasian outbreak, lessons learned from the 2014–15 North American HPAI outbreak, and associated challenges and opportunities.

Open-File Report↗
USGS2007

Modeling tradeoffs in avian life history traits and consequences for population growth

Variation in population dynamics is inherently related to life history characteristics of species, which vary markedly even within phylogenetic groups such as passerine birds. We computed the finite rate of population change (??) from a matrix projection model and from mark-recapture observations for 23 bird species breeding in northern Arizona. We used sensitivity analyses and a simulation model to separate contributions of different life history traits to population growth rate. In particular we focused on contrasting effects of components of reproduction (nest success, clutch size, number of clutches, and juvenile survival) versus adult survival on ??. We explored how changes in nest success or adult survival coupled to costs in other life history parameters affected ?? over a life history gradient provided by our 23 Arizona species, as well as a broader sample of 121 North American passerine species. We further examined these effects for more than 200 passeriform and piciform populations breeding across North America. Model simulations indicate nest success and juvenile survival exert the largest effects on population growth in species with moderate to high reproductive output, whereas adult survival contributed more to population growth in long-lived species. Our simulations suggest that monitoring breeding success in populations across a broad geographic area provides an important index for identifying neotropical migratory populations at risk of serious population declines and a potential method for identifying large-scale mechanisms regulating population dynamics. ?? 2007 Elsevier B.V. All rights reserved.

Ecological Modelling↗
USGS2013

Case study: Prioritization strategies for reforestation of minelands to benefit Cerulean Warblers

The central Appalachian landscape is being heavily altered by surface coal mining. The practice of Mountaintop Removal/Valley Fill (MTRVF) mining has transformed large areas of mature forest to non-forest and created much forest edge, affecting habitat quality for mature forest wildlife. The Appalachian Regional Reforestation Initiative is working to restore mined areas to native hardwood forest conditions, and strategies are needed to prioritize restoration efforts for wildlife. We present mineland reforestation guidelines for the imperiled Cerulean Warbler, considered a useful umbrella species, in its breeding range. In 2009, we surveyed forest predicted to have Cerulean Warblers near mined areas in the MTRVF region of West Virginia and Kentucky. We visited 36 transect routes and completed songbird surveys on 151 points along these routes. Cerulean Warblers were present at points with fewer large-scale canopy disturbances and more mature oak-hickory forest. We tested the accuracy of a predictive map for this species and demonstrated that it can be useful to guide reforestation efforts. We then developed a map of hot spot locations that can be used to determine potential habitat suitability. Restoration efforts would have greatest benefit for Cerulean Warblers and other mature forest birds if concentrated near a relative-abundance hot spot, on north- and east-facing ridgetops surrounded by mature deciduous forest, and prioritized to reduce edges and connect isolated forest patches. Our multi-scale approach for prioritizing restoration efforts using an umbrella species may be applied to restore habitat impacted by a variety of landscape disturbances.

Journal American Society of Mining and Reclamation↗
USGS1994

Emperor goose (Chen canagica)

Early naturalists exploring western Alaska were intrigued to find a stocky, blue-gray species of coastal goose unique to that area and nearby Russia. As E. W. Nelson (1887) wrote, "Among the various species of birds more or less peculiar to Alaska this goose is perhaps the most noteworthy." The Emperor Goose nests in the extensive coastal salt marsh habitats of arctic and sub-arctic Alaska and Russia and winters primarily on coastal beaches along ice-free areas of the Aleutian Islands and the Alaska Peninsula. Locally known as the "Beach Goose" from its habit of roosting and feeding near the waters' edge, the diet of this species consists largely of clams, mussels, and algae when wintering and staging in marine and estuarine habitats. When nesting in terrestrial habitats, it eats mostly roots, bulbs, and shoots of vegetation. Although the breeding biology and habitat requirements of this goose have been examined in detail, mostly on the Yukon-Kuskokwim Delta (Y-K Delta) of Alaska, there have been no intensive studies of its wintering or staging biology. Recent studies of migration have confirmed pathways and timing between the Y-K Delta and staging areas on the Alaska Peninsula and wintering areas largely on the Aleutian Islands (Hupp et al. 2007). Observations of substantial molt migrations to the Chukotka Peninsula in eastern Russia (Hupp et al. 2007) suggest a possible change in distribution, or at least a clarification, and raise the possibility of harvest mortality on both continents. Alaska's Emperor Goose population declined precipitously from 139,000 in 1964 to 42,000 in 1986, although its numbers have recovered slightly since then (Fischer et al. 2008). The factors responsible for this quick decline and slow recovery remain poorly known. Hunting, especially subsistence hunting by Native Americans, is probably a factor (Hupp et al. 2008b); coastal oil pollution could also be reducing the survival of overwintering individuals (Byrd et al. 1995); and interspecific competition among brood rearing geese may limit recovery through recruitment (Schmutz and Laing 2002, Lake et al. 2008).

Birds of North America↗
USGS2021

Migration phenology and patterns of American woodcock in central North America derived using satellite telemetry

American woodcock Scolopax minor (hereafter woodcock) migration ecology is poorly understood, but has implications for population ecology and management, especially related to harvest. To describe woodcock migration patterns and phenology, we captured and equipped 73 woodcock with satellite tracking devices in the Central Management Region (analogous to the Mississippi Flyway) of North America and documented migration paths of 60 individual woodcock and 87 autumn or spring woodcock migrations during 2014–2016. Woodcock migration at the scale of the Central Management Region was more synchronous in spring than in autumn, but unlike most other migratory birds, average duration of autumn migration (31 days) was shorter than duration of spring migration (53 days). This difference in migration duration resulted from woodcock making more close-together migratory stopovers during spring migration, not because woodcock had individual stopovers of longer duration. During autumn migration, the number of days, the number of stopovers, migration end date and net migration displacement were negatively related to initiation date and rate of migration, and the number of stopovers and the net migration displacement were negatively related with migration end date. Spring migration duration, end date, the number of stopovers and net migration displacement were negatively related to migration rate and initiation date was positively related to migration rate, suggesting that woodcock that initiated spring migration later had faster migration rates. Juvenile female woodcock began spring migration later than adult female woodcock. Our results provide a basis for comparing current harvest seasons with presence of migrating woodcock during autumn and provide insight into differential harvest of migratory versus local woodcock on breeding areas.

central North America↗
USGS2017

The influence of local- and landscape-level factors on wetland breeding birds in the Prairie Pothole Region of North and South Dakota

We examined the relationship between local- (wetland) and landscape-level factors and breeding bird abundances on 1,190 depressional wetlands in the Prairie Pothole Region of North and South Dakota during the breeding seasons in 1995–97. The surveyed wetlands were selected from five wetland classes (alkali, permanent, semipermanent, seasonal, or temporary), two wetland types (natural or restored), and two landowner groups (private or Federal). We recorded 133 species of birds in the surveyed wetlands during the 3 years. We analyzed the nine most common (or focal) species (that is, species that were present in 25 percent or more of the 1,190 wetlands): the Red-winged Blackbird ( Agelaius phoeniceus ), Blue-winged Teal ( Anas discors ), Mallard (Anas platyrhynchos ), American Coot ( Fulica americana ), Gadwall ( Anas strepera ), Common Yellowthroat ( Geothlypis trichas ), Yellow-headed Blackbird ( Xanthocephalus xanthocephalus ), Northern Shoveler ( Anas clypeata ), and Savannah Sparrow ( Passerculus sandwichensis ). Our results emphasize the ecological value of all wetland classes, natural and restored wetlands, and publicly and privately owned wetlands in this region, including wetlands that are generally smaller and shallower (that is, temporary and seasonal wetlands) and thus most vulnerable to drainage. Blue-winged Teal, Northern Shoveler, Gadwall, Common Yellowthroat, and Red-winged Blackbird had higher abundances on Federal than on private wetlands. Abundances differed among wetland classes for seven of the nine focal species: Blue-winged Teal, Northern Shoveler, Mallard, American Coot, Common Yellowthroat, Yellow-headed Blackbird, Red-winged Blackbird. American Coot had higher abundances on restored wetlands than on natural wetlands overall, and Gadwall and Common Yellowthroat had higher abundances on private restored wetlands than on private natural wetlands. The Common Yellowthroat was the only species that had higher abundances on restored private wetlands than on restored Federal wetlands. After adjusting for wetland size and the date and location of the surveys, our results demonstrated that incorporating wetland- and landscape-level factors in models can improve our ability to predict abundances of wetland birds in this region. The top model for eight of the nine focal species included wetland- and landscape-level factors, whereas the best model for Blue-winged Teal included only wetland-level attributes. Although local factors (for example, percent open water or emergent vegetation) in individual wetlands are important factors for some wetland breeding birds, it is important that natural resource managers consider landscape-level factors beyond the local factors in their conservation plans for wetland birds.

North Dakota, South Dakota↗
USGS2018

The Pothole Hydrology-Linked Systems Simulator (PHyLiSS)—Development and application of a systems model for prairie-pothole wetlands

The North American Prairie Pothole Region covers about 770,000 square kilometers of the United States and Canada (including parts of 5 States and 3 provinces: North Dakota, South Dakota, Montana, Minnesota, Iowa, Saskatchewan, Manitoba, and Alberta). The Laurentide Ice Sheet shaped the landscape of the region about 12,000 to 14,000 years ago. The retreat of the ice sheet left behind low-permeability glacial till and a landscape dotted with millions of depressions known today as prairie potholes. The wetlands that subsequently formed in these depressions, prairie-pothole wetlands, provide critical migratory-bird habitat and support dynamic aquatic communities. Extensive grasslands and productive agricultural systems surround these wetland ecosystems. In prairie-pothole wetlands, the compositions of plant, invertebrate, and vertebrate communities are highly dependent on hydrogeochemical conditions. Regional climate shifts between wet and dry periods affect the length of time that wetlands contain ponded surface water and the chemistry of that ponded water. Land-use change can exacerbate or reduce the effects of climate on wetland hydrology and water chemistry. A mechanistic understanding of the relation among climate, land use, hydrology, chemistry, and biota in prairie-pothole wetlands is needed to better understand the complex, and often interacting, effects of climate and land use on prairie-pothole wetland systems and to facilitate climate and land-use change adaptation efforts. The Pothole Hydrology-Linked Systems Simulator (PHyLiSS) model was developed to address this need. The model simulates water-surface elevation dynamics in prairie-pothole wetlands and quantifies changes in salinity. The PHyLiSS model is unique among other wetland models because it accommodates differing sizes and morphometries of wetland basins, is not dependent on a priori designations of wetland class, and allows for functional changes associated with dynamic shifts in ecohydrological states. The PHyLiSS model also has the capability to simulate wetland salinity, and potential future iterations will also simulate the effects of changing hydrology and geochemical conditions on biota. This report documents the development of the hydrological and geochemical components of the PHyLiSS model and provides example applications.

Open-File Report↗
USGS2022

Pink-footed Shearwater Ardenna creatopus

The Pink-footed Shearwater’s life history is tied to the Humboldt and California upwelling currents in the Eastern Pacific Ocean. It is larger than other shearwaters in its range, other than Flesh-footed Shearwater Ardenna carneipes. It is also distinct in appearance with pinkish bill and feet, pale underparts, and brown to grayish upperparts. It is known to breed on the Juan Fernández Islands and Isla Mocha, off central Chile. Birds spend the non-breeding period in waters off Peru and northward to waters off the west coast of North America. Breeding occurs in colonies, where pairs nest in burrows and the female lays a single egg. Breeding colonies generally are located on steep slopes in both open and forested habitats. During the breeding period, the species forages mainly in waters over the relatively narrow continental shelf as well as over deep offshore waters, depending on breeding colony. During the non-breeding period, individuals concentrate near the continental shelf-break and slope, and in more pelagic waters while making migratory movements. The Pink-footed Shearwater preys on fish and squid by seizing them at the surface or by making shallow dives. Foraging is often in association with albacore, dolphins, other seabirds, and fishing vessels. Pink-footed Shearwater is listed as Vulnerable by the IUCN and Endangered by Chile and Canada. Principal conservation threats are mortality from fisheries bycatch (especially in South American fisheries), and predation and habitat degradation from introduced mammals on breeding islands.

Birds of the World↗
USGS2002

Waterbird conservation for the Americas: The North American waterbird conservation plan, version 1

The North American Waterbird Conservation Plan (the Plan) is the product of an independent partnership of individuals and institutions having interest and responsibility for conservation of waterbirds and their habitats in the Americas. This partnership - Waterbird Conservation for the Americas - was created to support a vision in which the distribution, diversity, and abundance of populations and habitats of breeding, migratory, and nonbreeding waterbirds are sustained or restored throughout the lands and waters of North America, Central America, and the Caribbean. The Plan provides a continental-scale framework for the conservation and management of 210 species of waterbirds, including seabirds, coastal waterbirds, wading birds, and marshbirds utilizing aquatic habitats in 29 nations throughout North America, Central America, the islands and pelagic waters of the Caribbean Sea and western Atlantic, the U.S.-associated Pacific Islands and pelagic inland and pelagic waters of the Pacific. Birds as familiar as herons, loons, pelicans, and gulls, as well as the lesser known albatrosses, petrels, auks, and rails are among the species considered in the Plan. These birds' dependence on aquatic habitats such as wooded swamps, stream corridors, salt marshes, barrier islands, continental shelf waters and open pelagic waters make them especially vulnerable to the myriad threats facing water and wetland resources globally. In addition, the congregatory behavior of many waterbirds increases population risks by concentrating populations in limited areas.

Book↗
USGS2005

Invertebrate eggs can fly: Evidence of waterfowl-mediated gene flow in aquatic invertebrates

Waterfowl often have been assumed to disperse freshwater aquatic organisms between isolated wetlands, but no one has analyzed the impact of this transport on the population structure of aquatic organisms. For three cladocerans (Daphnia ambigua, Daphnia laevis, and Sida crystallina) and one bryozoan (Cristatella mucedo), we estimated the genetic distances between populations across North America using sequences of several mitochondrial DNA genes and genotypic frequencies at allozyme and microsatellite loci. Waterfowl movements across North America (estimated from band recovery data) explained a significant proportion of the gene flow occurring between populations across the continent for three of the four species, even after controlling for geographic distances between localities. The fourth species, S. crystallina, has propagules less likely to survive desiccation or ingestion by birds. Differences in the capacity to exploit bird-mediated transport are likely to have important consequences for the ecology of aquatic communities and the spread of invasive species.

American Naturalist↗
USGS2014

Delineation of Tundra Swan Cygnus c. columbianus populations in North America: geographic boundaries and interchange

North American Tundra Swans Cygnus c. columbianus are composed of two wellrecognised populations: an Eastern Population (EP) that breeds across northern Canada and north of the Brooks Range in Alaska, which migrates to the eastern seaboard of the United States, and a Western Population (WP) that breeds in coastal regions of Alaska south of the Brooks Range and migrates to western North America. We present results of a recent major ringing effort from across the breeding range in Alaska to provide a better definition of the geographic extent of the migratory divide in Alaska. We also reassess the staging and winter distributions of these populations based on locations of birds tracked using satellite transmitters, and recent recoveries and sightings of neck-collared birds. Summer sympatry of EP and WP Tundra Swans is very limited, and largely confined to a small area in northwest Alaska. Autumn migration pathways of EP and WP Tundra swans abut in southwest Saskatchewan, a region where migrating WP birds turn west, and EP birds deviate abruptly eastward. Overall, from 1989 to 2013 inclusive, 2.6% of recoveries or resightings reported to the USGS Bird Banding Laboratory were of birds that moved from the domain of the population in which they were initially captured to within the range of the other population; a proportion roughly comparable to the results of Limpert et al . (1991) for years before 1990. Of the 70 cross-boundary movements reported since 1989, 39% were of birds marked on breeding areas and 61% were of birds marked on wintering areas. Dispersing swans (i.e. those that made crossboundary movements) did not differ with respect to age or sex from those that did not move between populations. The Brooks Range in northern Alaska effectively separates the two populations within Alaska, but climate-induced changes in tundra breeding habitats and losses of wetlands on staging areas may alter the distribution for both of these populations.

Wildfowl↗
USGS2011

Use of early-successional managed northern forest by mature-forest species during the post-fledging period

In eastern North America, after the young fledge, both adult and juvenile mature-forest birds may use regenerating clearcuts, although which species frequent early-successional forest and during which life stages is not well documented. To assess whether birds nesting in mature forest in north-central Minnesota use regenerating clearcuts 2–10 years old, we netted after birds fledged (2006–2009) and during the breeding season (2009). In addition, we monitored Ovenbird ( Seiurus aurocapilla ) nests and banded nestlings in adjacent mature forest and estimated the age at which juveniles used regenerating clearcuts. While banding, we also recorded nests of any species encountered opportunistically in regenerating clearcuts as evidence of breeding in this cover type. During July and August, we captured 4556 birds of 62 species, of which 1746 (38%) were of 28 mature-forest species. As reported elsewhere, most (76%) mature-forest birds we captured were of only a few species: Ovenbird, American Redstart ( Setophaga ruticilla ), Least Flycatcher ( Empidonax minimus ), and Black-and-white Warbler ( Mniotilta varia ). In 2009, 21% of captures during the nesting period were of mature-forest birds. Comparing dates of fledging from monitored nests to dates of capture in clearcuts implies that nearly all (95%) hatch-year Ovenbirds using clearcuts were independent of adult care. Capture dates of juveniles of other mature-forest species were similar. Although we captured 340 hatch-year Ovenbirds in regenerating clearcuts, we captured only one of 424 Ovenbirds we had banded as nestlings in adjacent mature forest. Within the clearcuts, we encountered nests of five species that typically nest in mature forest.

Minnesota↗
USGS2012

Potential effects of climate change on the distribution of waterbirds in the Prairie Pothole Region, U.S.A.

Wetland-dependent birds are considered to be at particularly high risk for negative climate change effects. Current and future distributions of American Bittern ( Botaurus lentiginosus ), American Coot ( Fulica americana ), Black Tern ( Chlidonias niger ), Pied-billed Grebe ( Podilymbus podiceps ) and Sora ( Porzana carolina ), five waterbird species common in the Prairie Pothole Region (PPR), were predicted using species distribution models (SDMs) in combination with climate data that projected a drier future for the PPR. Regional-scale SDMs were created for the U.S. PPR using breeding bird survey occurrence records for 1971-2000 and wetland and climate parameters. For each waterbird species, current distribution and four potential future distributions were predicted: all combinations of two Global Circulation Models and two emissions scenarios. Averaged for all five species, the ensemble range reduction was 64%. However, projected range losses for individual species varied widely with Sora and Black Tern projected to lose close to 100% and American Bittern 29% of their current range. Future distributions were also projected to a hypothetical landscape where wetlands were numerous and constant to highlight areas suitable as conservation reserves under a drier future climate. The ensemble model indicated that northeastern North Dakota and northern Minnesota would be the best areas for conservation reserves within the U.S. PPR under the modeled conditions.

North Dakota;South Dakota;Minnesota;Iowa↗
USGS2014

West Nile Virus transmission in winter: the 2013 Great Salt Lake Bald Eagle and Eared Grebes Mortality event

West Nile Virus (WNV) infection has been reported in over 300 species of birds and mammals. Raptors such as eagles, hawks and falcons are remarkably susceptible, but reports of WNV infection in Bald Eagles (Haliaeetus leucocephalus) are rare and reports of WNV infection in grebes (Podicipediformes) even rarer. We report an unusually large wild bird mortality event involving between 15,000-20,000 Eared Grebes (Podiceps nigricollis) and over 40 Bald Eagles around the Great Salt Lake, Utah, in November-December 2013. Mortality in grebes was first reported in early November during a period when the area was unseasonably warm and the grebes were beginning to gather and stage prior to migration. Ten out of ten Eared Grebes collected during this period were WNV RT-PCR and/or isolation positive. This is the first report of WNV infection in Eared Grebes and the associated mortality event is matched in scale only by the combined outbreaks in American White Pelican (Pelecanus erythrorhynchos) colonies in the north central states in 2002-2003. We cannot be sure that all of the grebes were infected by mosquito transmission; some may have become infected through contact with WNV shed orally or cloacally from other infected grebes. Beginning in early December, Bald Eagles in the Great Salt Lake area were observed to display neurological signs such as body tremors, limb paralysis and lethargy. At least 43 Bald Eagles had died by the end of the month. Nine of nine Bald Eagles examined were infected with WNV. To the best of our knowledge, this is the largest single raptor mortality event since WNV became endemic in the USA. Because the majority of the eagles affected were found after onset of below-freezing temperatures, we suggest at least some of the Bald Eagles were infected with WNV via consumption of infected Eared Grebes or horizontal transmission at roost sites.

PLOS Current Outbreaks↗
USGS1997

Dramatic fluctuations in liver mass and metal content of eared grebes ( Podiceps nigricollis ) during autumnal migration

Adult eared grebes exhibit threefold fluctuation in body mass and up to a fivefold variation in liver weight during the course of their annual breeding and migratory cycle. Concentrations of 20 metals or metalloids were quantified in the liver from eared grebes obtained at three phases of their annual cycle: newly arrived migrants (July-August-September), staging (October-November), and immediate post-migration (December-January). Values for twelve elements (Al, B, Cd, Cr, Cu, Fe, Hg, Mg, Mn, Ni, Se, and Zn) that were detected in more than one-half of the samples were low. Hepatic concentrations of elements known to be toxic to free-ranging birds (e.g., Cd, Hg, Pb, Se) were well below known effect thresholds. No differences in metal concentrations were observed between newly arrived migrants and staging birds despite the large increases in body and liver mass. However, in the immediate post-migration period after body and liver mass have rapidly declined, Al values decreased, whereas Se and Zn concentrations actually increased. Total liver burdens of elements tended to be greatest in staging grebes compared to other collection periods, and paralleled changes in body and liver mass. The need for temporally- and physiologically-matched reference birds, and at least knowledge of circannual organ mass fluctuations, appears to be a requirement for ecotoxicological exposure assessments in species such as the eared grebe. Generation of additional avian toxicity data from controlled dosing studies during potentially vulnerable phases of their annual cycle (e.g., molt, post-migration) seems warranted. Although it is commonly accepted that hepatic metal concentrations are principally affected by contaminant exposure, we have shown differential alterations related to the stage of the annual cycle. Our findings may be of broad significance, as well as of immediate importance in resolving the cause of the die-off of approximately 150,000 eared grebes (perhaps 7% of the North American population) at the Salton Sea in 1991-1992.

Bulletin of Environmental Contamination and Toxico↗
USGS2000

Migration strategies and wintering areas of North American ospreys as revealed by satellite telemetry

Since 1995 we have trapped and tagged 110 Ospreys ( Pandion haliaetus ) from 12 study sites in 8 states (Fig. 1). This total includes 71 females, 32 males and 7 juveniles. Our study areas encompass the major Osprey population concentrations found in the United States including the Western States, the Great Lakes region and the Eastern Seaboard. Tagging of nesting pairs along with three complete family groups revealed that departure times from nesting areas varied by gender; with females leaving before the juveniles and the males departing last. Neither nesting pairs, nor families, migrated or wintered together (Fig. 2). Departure dates from the breeding areas ranged from 12 July to 1 October. Migration routes differed between populations but not gender (Fig. 3). Western Ospreys migrated through California and to a lesser degree other western states and then into Mexico. Minnesota Ospreys migrated along three routes; 1) through the central U.S. and then along the east coast of Mexico, 2) along the Mississippi River then across the Gulf of Mexico, or 3) through the Southeastern U.S., then across the Caribbean. East Coast birds migrated along the Eastern Seaboard of the U.S. through Florida and across the Caribbean.

Arkansas, Illinois, Iowa, Louisiana, Minnesota, Mi↗
USGS2004

Winter survival of lesser scaup in east-central Florida

The North American continental population of lesser scaup (Aythya affinis) has been declining since the mid-1980s. Seasonal survival estimates may provide insights about the ecological basis for this decline, but such data are not available. We estimated post-harvest winter survival of lesser scaup in east-central Florida, USA, where 62% of the Atlantic Flyway population winters. The Kaplan-Meier survival estimate from 11 January to 14 March 2002 was 0.95 ?? 0.04 (SE) for females and 0.90 ?? 0.09 for males. These estimates were not different (P = 0.64), and pooled survival was 0.93 ?? 0.04. Temporary emigration (movement out of and return to the study area) was exhibited by 25% of the birds during survey periods, but absences were short and were believed to have had little effect on precision of survival estimates. Our findings suggested that natural mortality at Merritt Island National Wildlife Refuge (MINWR) and surrounding estuarine areas was relatively low. Our results also indicate that habitat quality in this portion of east-central Florida was sufficient to meet overwintering requirements and likely contributed to the reported survival rates. Estimating survival during other stages of the annual cycle, as well as an overall winter estimate reflecting harvest mortality, is necessary to determine whether low survival rates are responsible for continental population declines.

Journal of Wildlife Management↗