Richard Bierregaard

Academy of Natural Sciences of Drexel University · Ornithology

Recent long-term studies in protected areas have revealed the loss of biodiversity, yet the ramifications for ecosystem health and resilience remain unknown. Here, we investigate how the loss of understory birds, in the lowest stratum of the forest, affects avian biomass and functional diversity in the Amazon rainforest. Across approximately 30 yea...

For many avian species, spatial migration patterns remain largely undescribed, especially across hemispheric extents. Recent advancements in tracking technologies and high‐resolution species distribution models (i.e., eBird Status and Trends products) provide new insights into migratory bird movements and offer a promising opportunity for integrati...

Warming from climate change is expected to reduce body size of endotherms, but studies from temperate sys­tems have produced equivocal results. Over four decades, we collected morphometric data on a nonmigratory understory bird community within Amazonian primary rainforest that is experiencing increasingly extreme climate. All 77 species showed low...

Flying over the open sea is energetically costly for terrestrial birds. Despite this, over-water journeys of many birds, sometimes hundreds of kilometres long, are uncovered by bio-logging technology. To understand how these birds afford their flights over the open sea, we investigated the role of atmospheric conditions, specifically wind and uplif...

How are rainforest birds faring in the Anthropocene? We use bird captures spanning > 35 years from 55 sites within a vast area of intact Amazonian rainforest to reveal reduced abundance of terrestrial and near‐ground insectivores in the absence of deforestation, edge effects or other direct anthropogenic landscape change. Because undisturbed forest...

Timing of activity can reveal an organism's efforts to optimize foraging either by minimizing energy loss through passive movement or by maximizing energetic gain through foraging. Here, we assess whether signals of either of these strategies are detectable in the timing of activity of daily, local movements by birds. We compare the similarities of...

Timing of activity can reveal an organism's efforts to optimize foraging either by minimizing energy loss through passive movement or by maximizing energetic gain through foraging. Here, we assess whether signals of either of these strategies are detectable in the timing of activity of daily, local movements by birds. We compare the similarities of...

The open sea is considered an ecological barrier to terrestrial bird movement. However, over-water journeys of many terrestrial birds, sometimes hundreds of kilometers long, are being uncovered by bio-logging technology. To understand how these birds afford their flights over the open sea, we investigated the role of atmospheric conditions in subsi...

Habitat destruction and degradation are the leading causes of species declines and extinctions in the world. Human altered landscapes often leave fragments of previously continuous habitat, which may be of significant conservation value. We assessed the effects of habitat fragmentation on the taxonomic diversity, community composition, and nestedne...

Background Vast areas of lowland neotropical forest have regenerated after initially being cleared for agricultural purposes. The ecological value of regenerating second growth to forest-dwelling birds may largely depend on the age of the forest, associated vegetative structure, and when it is capable of sustaining avian demographics similar to tho...

Aim Animal movement is an important determinant of individual survival, population dynamics and ecosystem structure and function. Nonetheless, it is still unclear how local movements are related to resource availability and the spatial arrangement of resources. Using resident bird species and migratory bird species outside the migratory period, we...

In an old residential neighborhood of Charlotte, North Carolina, the loud, baritone call of a barred owl (Strix varia) breaks the quiet of a late winter evening, not so much asking as demanding to know “Who cooks for you, who cooks for you-all?” His mate responds, in a slightly higher key, and their conversation escalates into a raucous caterwaulin...

Collision with vehicles is a major if not the dominant source of mortality for owls. Despite this, there has been no study to date on Barred Owl-vehicle collisions, a species that breeds in densely-populated suburban neighborhoods with high road density. We capitalized on the availability of a large dataset of the locations of Barred Owls hit by ve...

To compensate for drift, an animal migrating through air or sea must be able to navigate. Although some species of bird, fish, insect, mammal, and reptile are capable of drift compensation, our understanding of the spatial reference frame, and associated coordinate space, in which these navigational behaviors occur remains limited. Using high resol...

North American Ospreys (Pandion haliaetus) typically migrate long distances to their wintering grounds in the tropics. Beyond the general distribution of their wintering range (i.e., the Caribbean, South America, and Central America), very little is known about the wintering ecology of these birds. We used satellite telemetry to determine the durat...

Migración Primaveral de Individuos Adultos de Pandion haliaetus La mayoría de los individuos de Pandion haliaetus son migratorios, reproduciéndose en latitudes hacia el norte y migrando largas distancias hacia y desde los sitios de invernada en los trópicos. Aunque los patrones de migración otoñal de P. haliaetus han sido descriptos y estudiados, s...

The Osprey (Pandion haliaetus) population nesting between New York City and Boston, Massachusetts, collapsed from approximately 1000 pairs in 1940 to 109 in the early 1970s. In the 1970s, within five or six years of the cessation of DDT use in the region, the Osprey population began recovering. The recovery was asynchronous across the region. Curre...

Ospreys (Pandion haliaetus) are remarkable raptors. Their choice of conspicuous nest sites and surprising tolerance for nesting in nearly intimate association with humans render them an iconic piece of aquatic ecosystems in both marine and freshwater habitats across the northern hemisphere and much of Australasia (Australia to Indonesia). Wintering...

Background/Question/Methods For decades, researchers have studied fundamental questions of how Amazonian biodiversity is maintained, and whether that diversity can persist as Amazonian forests are increasingly perturbed. Our approach to addressing these questions has changed, however, as theory and empirical understanding have developed. The long...

Although it has long been recognized that many tropical birds do not share the same narrow breeding periods as temperate birds, conventional thinking considers tropical breeding seasons to be discrete periods generally governed by rainfall seasonality. We used a database of >31,000 captures of 104 species collected over 17 years in rainforest near...

The energetically challenging periods of molting and breeding are usually temporally separated in temperate birds, but can occur simultaneously in tropical birds, a condition known as molt—breeding overlap. Here, we document great variation in the timing and duration of molting and breeding, and in the extent of molt-breeding overlap, among 87 spec...

All species captured before isolation and their status in 2007. For each fragment size class, ‘Pre’ is the number of fragments where the species was detected preisolation, and ‘2007’ is the number of those same fragments where it was detected by any means in 2007 (thus a fragment where a species was detected only in 2007 does not get counted). ‘200...

Extinctions between preisolation and 2007 by fragment size class. ‘Extinct species’ and ‘Proportion of species extinct’ include all species that went extinct in any fragment of that size class, even if the species persisted in other fragments of the same size class. ‘Proportion of possible extinctions’ represents the total number of species x fragm...

Inferences about species loss following habitat conversion are typically drawn from short-term surveys, which cannot reconstruct long-term temporal dynamics of extinction and colonization. A long-term view can be critical, however, to determine the stability of communities within fragments. Likewise, landscape dynamics must be considered, as second...

Tropical deforestation often produces landscapes characterized by isolated patches of forest habitat surrounded by pasture, agriculture, or regrowth vegetation. Both the size and the distribution of these forest patches may influence the long-term persistence of faunal species. There is, therefore, a pressing need to understand faunal responses to...

In this paper we describe band-recovery data from 90 ospreys (Pandion haliaetus), banded in North America and recovered in Brazil between 1937 and 2006. Data were obtained from the Bird Banding Laboratory (US Geological Survey, USA) and from the Centro Nacional de Pesquisa para Conservação das Aves Silvestres (IBAMA, Brazil). The majority of osprey...