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At least 1,711 records · Page 95Linked to original sources
USGS2025

Waterfowl endozoochory: Traits drive plant-bird dispersal interactions in North America

Plant biogeography and ongoing changes in plant distributions are influenced by long-distance dispersal (LDD) of seeds, and migratory waterfowl (Anatidae: Ducks, geese and swans) are particularly important for the dispersal of plants in and around wetlands through gut passage (endozoochory). However, this dispersal is not contemplated by classical dispersal syndromes; hence, currently we have limited understanding of what angiosperm traits predict seed dispersal by waterfowl and any differences due to avian trait variation among waterfowl species. We conducted a literature search for data on the presence of seeds in the alimentary canal or faeces of North American waterfowl as a proxy for dispersal interactions, since an important fraction of these seeds survives gut passage. We present a list of North American flowering plant species ( N = 536) from 95 families potentially dispersed by 38 waterfowl species, together with traits of these plants and their vectors. Owing largely to limited sampling effort, 47% of plant species and 35% of plant genera recorded were only found in a single waterfowl species. A suite of analytical approaches revealed major differences in the traits of plants whose seeds are ingested and likely dispersed between foraging groups (guilds) and in relation to other waterfowl traits. Diving ducks and sea ducks are associated with sublittoral plants that have submerged or floating leaves, and hence with the classical hydrochory syndrome. Dabbling ducks and herbivorous waterfowl (notably geese) are associated with terrestrial herbaceous plants, and also with the unspecialised dispersal syndrome common in terrestrial plants. Plants with larger seeds or of greater height are more likely to be dispersed by dabbling ducks, whereas shorter plants are more likely to be dispersed by geese than by other waterfowl. Network analyses of interactions between waterfowl species and plant traits were generally consistent with these results, but also provided evidence that not all geese, dabbling ducks, or sea duck species are alike in their interactions with plants along the terrestrial–aquatic gradient, but instead occupy distinct dispersal niches. The traditional classification of waterfowl into guilds therefore does not accurately reflect their differing roles in the ingestion and dispersal of plant seeds. Aquatic plant species had more vector species than terrestrial ones. Detailed studies of waterfowl endozoochory and more trait determinations for North American plants are needed to facilitate predictions of LDD as waterfowl population sizes and migration patterns vary in the future with climate change.

Freshwater Biology↗
USGS2009

A spatial model of bird abundance as adjusted for detection probability

Modeling the spatial distribution of animals can be complicated by spatial and temporal effects (i.e. spatial autocorrelation and trends in abundance over time) and other factors such as imperfect detection probabilities and observation-related nuisance variables. Recent advances in modeling have demonstrated various approaches that handle most of these factors but which require a degree of sampling effort (e.g. replication) not available to many field studies. We present a two-step approach that addresses these challenges to spatially model species abundance. Habitat, spatial and temporal variables were handled with a Bayesian approach which facilitated modeling hierarchically structured data. Predicted abundance was subsequently adjusted to account for imperfect detection and the area effectively sampled for each species. We provide examples of our modeling approach for two endemic Hawaiian nectarivorous honeycreepers: 'i'iwi Vestiaria coccinea and 'apapane Himatione sanguinea. ?? 2009 Ecography.

Ecography↗
USGS2022

Microbiomes associated with avian malaria survival differ between susceptible Hawaiian honeycreepers and sympatric malaria-resistant introduced birds

Of the estimated 55 Hawaiian honeycreepers (subfamily Carduelinae) only 17 species remain, nine of which the International Union for Conservation of Nature considers endangered. Among the most pressing threats to honeycreeper survival is avian malaria, caused by the introduced blood parasite Plasmodium relictum , which is increasing in distribution in Hawaiʻi as a result of climate change. Preventing further honeycreeper decline will require innovative conservation strategies that confront malaria from multiple angles. Research on mammals has revealed strong connections between gut microbiome composition and malaria susceptibility, illuminating a potential novel approach to malaria control through the manipulation of gut microbiota. One honeycreeper species, Hawaiʻi ʻamakihi ( Chlorodrepanis virens ), persists in areas of high malaria prevalence, indicating they have acquired some level of immunity. To investigate if avian host-specific microbes may be associated with malaria survival, we characterized cloacal microbiomes and malaria infection for 174 ʻamakihi and 172 malaria-resistant warbling white-eyes ( Zosterops japonicus ) from Hawaiʻi Island using 16S rRNA gene metabarcoding and quantitative polymerase chain reaction. Neither microbial alpha nor beta diversity covaried with infection, but 149 microbes showed positive associations with malaria survivors. Among these were Escherichia and Lactobacillus spp . , which appear to mitigate malaria severity in mammalian hosts, revealing promising candidates for future probiotic research for augmenting malaria immunity in sensitive endangered species.

Hawaii↗
USGS1968

Chlorinated hydrocarbons and eggshell changes in raptorial and fish-eating birds

Catastrophic declines of three raptorial species in the United States have been accompanied by decreases in eggshell thickness that began in 1947, have amounted to 19 percent or more, and were identical to phenomena reported in Britain. In 1967, shell thickness in herring gull eggs from five states decreased with increases in chlorinated hydrocarbon residues.

Science↗
USGS2023

Structure of breeding calls in three closely related bird species (Calidris Merrem, 1804; Scolopacidae)

We studied calls of three sandpiper species to document species’ similarities and differences. We hypothesized that functionally different calls would differ in degree of divergence. We studied two nuptial calls (complex “Song” and rhythmically repeated aerial call, RRC) of males, and a general-purpose call (“alarm” trill, AT) given by parents of both sexes in the presence of humans and other potential predators, in great knot, Calidris tenuirostris (Horsfeld, 1821); surfbird, Calidris virgata (Gmelin, 1789); and red knot, Calidris canutus (Linnaeus, 1758). Calls diverged unevenly across species—RRCs and Song diverged the most and ATs the least. Vocalizations of great knot and surfbird were most similar to one another, in agreement with a recently proposed phylogeny. Despite species differences in single acoustic traits, calls were evolutionarily conservative at higher structural levels, such as rhythmic temporal delivery of RRCs and harmonic structure (e.g., the fundamental frequency was suppressed in some call types). Some acoustic qualities that differed across species were similar across call types within species (e.g., tonality in red knot calls). Trait similarity across different calls suggests that a species’ calls cannot evolve independently of one another: common mechanisms of vocal production across different calls may impede differentiation within a species’ repertoire.

Canadian Journal of Zoology↗
USGS2009

Evidence that pairing with genetically similar mates is maladaptive in a monogamous bird

Background Evidence of multiple genetic criteria of mate choice is accumulating in numerous taxa. In many species, females have been shown to pair with genetically dissimilar mates or with extra-pair partners that are more genetically compatible than their social mates, thereby increasing their offsprings' heterozygosity which often correlates with offspring fitness. While most studies have focused on genetically promiscuous species, few studies have addressed genetically monogamous species, in which mate choice tends to be mutual. Results Here, we used microsatellite markers to assess individual global heterozygosity and genetic similarity of pairs in a socially and genetically monogamous seabird, the black-legged kittiwake Rissa tridactyla . We found that pairs were more genetically dissimilar than expected by chance. We also identified fitness costs of breeding with genetically similar partners: (i) genetic similarity of pairs was negatively correlated with the number of chicks hatched, and (ii) offspring heterozygosity was positively correlated with growth rate and survival. Conclusion These findings provide evidence that breeders in a genetically monogamous species may avoid the fitness costs of reproducing with a genetically similar mate. In such species that lack the opportunity to obtain extra-pair fertilizations, mate choice may therefore be under high selective pressure.

Alaska↗
USGS2025

Fitness consequences of catastrophic wildfire are mitigated by behavioral responses of an iconic bird

Background Drought, human disturbance, and invasive species are reshaping disturbance regimes and increasing the scale, severity, and frequency of wildfire in many ecosystems around the globe, including the sagebrush steppe of western North America. Recent studies suggested greater sage-grouse ( Centrocercus urophasianus ) adhere to strong site fidelity in the aftermath of wildfire, remaining inside fire perimeters for nesting and brood rearing despite negative consequences for survival and reproduction. Sage-grouse in Idaho exhibited context-dependent changes to space use after a large, high-severity fire that burned > 40,000 ha, yet the specific behavioral responses to fire and their fitness consequences remain unclear. We used data collected from 269 hens over a 6-year period under a multi-level before-after-control-impact design to test the hypothesis that sage-grouse mitigated fitness consequences of high-severity wildfire through adaptive behavioral responses and spatial redistribution. Results We tested predictions deduced from our hypothesis at the population and individual levels using behavioral, demographic, and life history data, including nesting metrics, brood-rearing metrics, hen survival, and body mass at capture. Fifteen of 16 predictions were supported, demonstrating that post-fire space use and avoidance of the burn was adaptive and helped mitigate fitness effects of the fire. Short-term consequences included elimination of nesting and brood rearing habitat and subsequent shifts to the distribution of usable space. Yet fitness consequences were minimal because of behavioral flexibility employed by hens during nesting and brood rearing. Conclusions Behavioral responses to wildfire by sage-grouse are more flexible than has been described, and sage-grouse demonstrated resilience by rapidly adapting space use to avoid short-term consequences of catastrophic fire when high-quality habitat remained adjacent to the burn and within their seasonal range. Our results imply behavioral and fitness consequences of fire are context-dependent and likely impacted by attributes of the fire and surrounding landscape after disturbance. Furthermore, among-study differences in behavioral and fitness outcomes of sage-grouse after fire supported underappreciated predictions from both fire ecology and site fidelity theory, and suggest conditions where behavioral flexibility should be expressed, and fidelity relaxed, based on severity of disturbance, landscape context, and species mobility.

Idaho↗
USGS2011

Lead in birds

Lead is a highly toxic heavy metal that acts as a nonspecific poison affecting all body systems and has no known biological requirement. Absorption of low concentrations may result in a wide range of sublethal effects in animals, and higher concentrations may result in mortality (Demayo et al. 1982). Lead has been mined and smelted by humans for centuries, but the use of lead-based products increased greatly following the Industrial Revolution. Consequently, lead today is ubiquitous in air, water, and soil, in both urban and rural environments (Eisler 2000). Vertebrates are exposed to lead mainly via inhalation and ingestion. A proportion of lead entering the body is absorbed into the bloodstream and subsequently becomes distributed among body tissues, primarily the blood, liver, kidney, and bone. As a result of anthropogenic activities, most animals have higher tissue lead concentrations than in preindustrialized times. Although even very low tissue lead concentrations have some measurable physiological effects, the concentrations usually encountered in the wider environment (i.e., distant from lead emission sources) have not generally been considered to directly affect survival of most wildlife.

Book chapter↗
USGS2016

Migratory bird habitat in relation to tile drainage and poorly drained hydrologic soil groups

The Prairie Pothole Region (PPR) is home to more than 50% of the migratory waterfowl in North America. Although the PPR provides an abundance of temporary and permanent wetlands for nesting and feeding, increases in commodity prices and agricultural drainage practices have led to a trend of wetland drainage. The Northern Shoveler is a migratory dabbling duck species that uses wetland habitats and cultivated croplands in the PPR. Richland County in North Dakota and Roberts County in South Dakota have an abundance of wetlands and croplands and were chosen as the study areas for this research to assess the wetland size and cultivated cropland in relation to hydrologic soil groups for the Northern Shoveler habitat. This study used geographic information system data to analyze Northern Shoveler habitats in association with Natural Resource Conservation Service soil data. Habitats, which are spatially associated with certain hydrologic soil groups, may be at risk of artificial drainage installations because of their proximity to cultivated croplands and soil lacking in natural drainage that may become wet or inundated. Findings indicate that most wetlands that are part of Northern Shoveler habitats were within or adjacent to cultivated croplands. The results also revealed soil hydrologic groups with high runoff potential and low water transmission rates account for most of the soil within the Northern Shoveler‘s wetland and cropland habitats. Habitats near agriculture with high runoff potential are likely to be drained and this has the potential of reducing Northern Shoveler habitat.

Conference Paper↗
USGS2016

Impacts of short-rotation early-growing season prescribed fire on a ground nesting bird in the central hardwoods region of North America

Landscape-scale short-rotation early-growing season prescribed fire, hereafter prescribed fire, in upland hardwood forests represents a recent shift in management strategies across eastern upland forests. Not only does this strategy depart from dormant season to growing season prescriptions, but the strategy also moves from stand-scale to landscape-scale implementation (>1,000 ha). This being so, agencies are making considerable commitments in terms of time and resources to this management strategy, but the effects on wildlife in upland forests, especially those dominated by hardwood canopy species, are relatively unknown. We initiated our study to assess whether this management strategy affects eastern wild turkey reproductive ecology on the Ozark-St. Francis National Forest. We marked 67 wild turkey hens with Global Positioning System (GPS) Platform Transmitting Terminals in 2012 and 2013 to document exposure to prescribed fire, and estimate daily nest survival, nest success, and nest-site selection. We estimated these reproductive parameters in forest units managed with prescribed fire (treated) and units absent of prescribed fire (untreated). Of 60 initial nest attempts monitored, none were destroyed or exposed to prescribed fire because a majority of fires occurred early than a majority of the nesting activity. We found nest success was greater in untreated units than treated units (36.4% versus 14.6%). We did not find any habitat characteristic differences between successful and unsuccessful nest-sites. We found that nest-site selection criteria differed between treated and untreated units. Visual concealment and woody ground cover were common selection criteria in both treated and untreated units. However, in treated units wild turkey selected nest-sites with fewer small shrubs (<5 cm ground diameter) and large trees (>20 cm DBH) but not in untreated units. In untreated units wild turkey selected nest-sites with more large shrubs (≥5cm ground diameter) but did not select for small shrubs or large trees. Our findings suggest that wild turkey have not benefited from the reintroduction of prescribed fire to the WRERA.

Arkansas↗
USGS1998

Birds of the Indigirka River Delta, Russia: Historical and biogeographic comparisons

We documented the breeding status and relative abundance of all avian species on the coastal portion of the Indigirka River Delta during spring and summer 1993-95. Data on avifaunal composition were then compared to data from adjacent areas from Eastern Siberia to the Chukotka Peninsula to evaluate how species composition changes longitudinally within the arctic and typical tundra zones of northern Russia. We recorded 63 species on the Indigirka River Delta, 37 (58.7 %) of which were confirmed breeders during at least one of the three years. Five new species were recorded breeding ( Arenaria interpres , Calidris acuminata , Limnodromus scolopaceus , Stercorarius parasiticus , and Asio flammeus ), and 13 previously unrecorded species were observed during this study. We also identified several species of rare or threatened status in Russia and North America, including Branta bernicla , Somateria fischeri , Polysticta stelleri , and Rhodostethia rosea . We used parsimony and distance matrix methods to compare the breeding species richness on the Indigirka River Delta to that of six other Russian Arctic areas. Biogeographic comparisons revealed the presence of two clades in the Russian Arctic: the Lena River Delta east to Chaun Delta and the Chukotka Peninsula.

Indigirka River Delta↗
USGS2011

Dynamic habitat selection by two wading bird species with divergent foraging strategies in a seasonally fluctuating wetland

Seasonal and annual variation in food availability during the breeding season plays an influential role in the population dynamics of many avian species. In highly dynamic ecosystems like wetlands, finding and exploiting food resources requires a flexible behavioral response that may produce different population trends that vary with a species' foraging strategy. We quantified dynamic foraging-habitat selection by breeding and radiotagged White Ibises ( Eudocimus albus ) and Great Egrets ( Ardea alba ) in the Florida Everglades, where fluctuation in food resources is pronounced because of seasonal drying and flooding. The White Ibis is a tactile “searcher” species in population decline that specializes on highly concentrated prey, whereas the Great Egret, in a growing population, is a visual “exploiter” species that requires lower prey concentrations. In a year with high food availability, resource-selection functions for both species included variables that changed over multiannual time scales and were associated with increased prey production. In a year with low food availability, resource-selection functions included short-term variables that concentrated prey (e.g., water recession rates and reversals in drying pattern), which suggests an adaptive response to poor foraging conditions. In both years, the White Ibis was more restricted in its use of habitats than the Great Egret. Real-time species—habitat suitability models were developed to monitor and assess the daily availability and quality of spatially explicit habitat resources for both species. The models, evaluated through hindcasting using independent observations, demonstrated that habitat use of the more specialized White Ibis was more accurately predicted than that of the more generalist Great Egret.

The Auk↗
USGS2012

Adaptive breeding habitat selection: Is it for the birds?

The question of why animals choose particular habitats has important implications for understanding behavioral evolution and distribution of organisms in the wild and for delineating between habitats of different quality for conservation and management. Habitats chosen by animals can influence fitness outcomes via the costs (e.g., predation risk) and benefits (e.g., food availability) of habitat use. Habitat preferences should therefore be under selection to favor those that confer fitness advantages (Clark and Shutler 1999). Indeed, prevailing theory suggests that the habitat preferences of animals should be adaptive, such that fitness is higher in preferred habitats (Hildén 1965, Southwood 1977, Martin 1998). However, studies have often identified apparent mismatches between observed habitat preferences and fitness outcomes across a wide variety of taxa (Valladares and Lawton 1991, Mayhew 1997, Kolbe and Janzen 2002, Arlt and Pärt 2007, Mägi et al. 2009). Certainly, one limitation of studies may be that assessment of “fitness” is typically constrained to fitness surrogates such as nest success rather than lifetime reproductive success or classic Fisherian fitness (Endler 1986). Nevertheless, important habitat choices such as nest sites influence the probability that temporarily sedentary, dependent young are discovered by enemies such as predators and parasites. We therefore expect, on average, to see congruence between evolved habitat preferences and relevant components of fitness (e.g., nest success). Here, we (1) review the prevalence of apparent mismatches between avian breeding-habitat preferences and fitness outcomes using nest-site selection as a focus; (2) describe several potential mechanisms for such mismatches, including anthropogenic, methodological, and ecological–evolutionary; and (3) suggest a framework for understanding the contexts in which habitat preferences represent adaptive decisions, with a primary focus on ecological information theory. We largely focus on habitat selection as a behavioral process at the scale of individuals (e.g., Robertson and Hutto 2006), rather than at the scale of population-level patterns (Fretwell and Lucas 1970, Morris 2003, Johnson 2007). However, these two scales cannot be wholly divorced from one another, as we will discuss.

The Auk↗
USGS2011

Proactive conservation management of an island-endemic bird species in the face of global change

Biodiversity conservation in an era of global change and scarce funding benefits from approaches that simultaneously solve multiple problems. Here, we discuss conservation management of the island scrub-jay ( Aphelocoma insularis ), the only island-endemic passerine species in the continental United States, which is currently restricted to 250-square-kilometer Santa Cruz Island, California. Although the species is not listed as threatened by state or federal agencies, its viability is nonetheless threatened on multiple fronts. We discuss management actions that could reduce extinction risk, including vaccination, captive propagation, biosecurity measures, and establishing a second free-living population on a neighboring island. Establishing a second population on Santa Rosa Island may have the added benefit of accelerating the restoration and enhancing the resilience of that island's currently highly degraded ecosystem. The proactive management framework for island scrub-jays presented here illustrates how strategies for species protection, ecosystem restoration, and adaptation to and mitigation of climate change can converge into an integrated solution.

California↗
USGS2012

Bird-habitat relationships in interior Columbia Basin shrubsteppe

Vegetation structure is considered an important habitat feature structuring avian communities. In the sagebrush biome, both remotely-sensed and field-acquired measures of big sagebrush (Artemisia tridentata) cover have proven valuable in understanding avian abundance. Differences in structure between the exotic annual cheatgrass (Bromus tectorum) and native bunchgrasses are also expected to be important. We used avian abundance data from 318 point count stations, coupled with field vegetation measurements and a detailed vegetation map, to model abundance for four shrub- and four grassland-associated avian species in southeastern Washington shrubsteppe. Specifically, we ask whether species distinguish between bunchgrass and cheatgrass, and whether mapped, categorical cover types adequately explain species' abundance or whether fine-grained, field-measured differences in vegetation cover are also important. Results indicate that mapped cover types alone can be useful for predicting patterns of distribution and abundance within the sagebrush biome for several avian species (five of eight studied here). However, field-measured sagebrush cover was a strong positive predictor for Sage Sparrow (Amphispiza belli), the only sagebrush obligate in this study, and a strong negative predictor for two grassland associates, Horned Lark (Eremophila alpestris) and Grasshopper Sparrow (Ammodramus savannarum). Likewise, shrub associates did not differ in abundance in sagebrush with a cheatgrass vs. bunchgrass understory, but grassland associates were more common in either bunchgrass (Horned Lark and Grasshopper Sparrow) or cheatgrass grasslands (Long-billed Curlew, Numenius americanus), or tended to use sagebrush-cheatgrass less than sagebrush-bunchgrass (Horned Lark, Grasshopper Sparrow, and Savannah Sparrow, Passerculus sandwichensis).

The Condor↗