Richard O. Bierregaard

Tropical Forest Remnants: Ecology, Management and Conservation of Fragmented Communities

The fragmentation of the tropical rain forests is the subject of this study, which looks at the devastating damage caused to these sensitive areas. By the year 2000 more than half of these forests will have been cut, causing increased soil erosion, watershed destabilization, climate degradation, and extinction of as many as 600,000 species. This volume summarizes what is known about the ecology, management, restoration, socioeconomics and conservation of fragmented forests, and identify key priorities for future work. Covering geographic areas from Southeast Asia and Australia to Madagascar and the New World, the book encapsulates contemporary knowledge and research. Thirty-three papers present the results of recent research and updates from decades-long projects in progress.

The biological dynamics of tropical rainforest fragments A prospective comparison of fragments and continuous forest

Richard 0. Bierregaard Jr. is director of the Biological Dynamics of Forest Fragment Project at the National Museum of Natural History, Smithsonian Institution, Washington, DC 20560; his research focuses on avian community structure in Amazonian rainforests, particularly the responses of such communities to forest fragmentation. Thomas E. Lovejoy is the Assistant Secretary for External Affairs of the Smithsonian Institution, Washington, DC 20560. Valerie Kapos is a research associate in the Department of Botany, University of Cambridge, Cambridge CB2 3EA, United Kingdom and at the University of North Wales; her research is on water and nutrient relations and phenology of tropical deciduous trees and edge effects on environment and plant responses. Angelo Augusto dos Santos is the coordinator for international cooperation at Brazils National Institute for Amazonian Research (INPA) and the Brazilian co-principal investigator of BDFFP at the National Museum of Natural History, Smithsonian Institution, Washington, DC 20560; his research focuses on the structure and ecology of tropical rainforest fragments. Roger W. Hutchings is the field director of BDFFP, Ecologia/V-8, INPA, C.P. 478, 69.011 Manaus, AM, Brazil; his research interests include butterflies in tropical forest fragments and adjacent continuous forest, botanical ecology, and general conservation biology of tropical rainforests. A mosaic of small

Rates of species loss from Amazonian forest fragments

In the face of worldwide habitat fragmentation, managers need to devise a time frame for action. We ask how fast do understory bird species disappear from experimentally isolated plots in the Biological Dynamics of Forest Fragments Project, central Amazon, Brazil. Our data consist of mist-net records obtained over a period of 13 years in 11 sites of 1, 10, and 100 hectares. The numbers of captures per species per unit time, analyzed under different simplifying assumptions, reveal a set of species-loss curves. From those declining numbers, we derive a scaling rule for the time it takes to lose half the species in a fragment as a function of its area. A 10-fold decrease in the rate of species loss requires a 1,000-fold increase in area. Fragments of 100 hectares lose one half of their species in <15 years, too short a time for implementing conservation measures.

Understory Bird Communities in Amazonian Rainforest Fragments: Species Turnover through 25 Years Post-Isolation in Recovering Landscapes

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 growth structure and overall forest cover contribute to processes in fragments. Here we examine bird communities in 11 Amazonian rainforest fragments of 1–100 ha, beginning before the fragments were isolated in the 1980s, and continuing through 2007. Using a method that accounts for imperfect detection, we estimated extinction and colonization based on standardized mist-net surveys within discreet time intervals (1–2 preisolation samples and 4–5 post-isolation samples). Between preisolation and 2007, all fragments lost species in an area-dependent fashion, with loss of as few as <10% of preisolation species from 100-ha fragments, but up to 70% in 1-ha fragments. Analysis of individual time intervals revealed that the 2007 result was not due to gradual species loss beginning at isolation; both extinction and colonization occurred in every time interval. In the last two samples, 2000 and 2007, extinction and colonization were approximately balanced. Further, 97 of 101 species netted before isolation were detected in at least one fragment in 2007. Although a small subset of species is extremely vulnerable to fragmentation, and predictably goes extinct in fragments, developing second growth in the matrix around fragments encourages recolonization in our landscapes. Species richness in these fragments now reflects local turnover, not long-term attrition of species. We expect that similar processes could be operating in other fragmented systems that show unexpectedly low extinction.

The biology and conservation status of Central and South American Falconiformes: a survey of current knowledge

Based on an extensive literature review for the 81 species of Falconiformes (excluding vultures) that breed primarily in Central and South America, I summarize the current state of our knowledge of the biology and conservation status of these birds. Most of what is known about the diurnal raptors in the region is based on studies carried out in the southern U.S.A., the Peten of Guatemala, extreme north-eastern South America (Venezuela through the Guianas) and Chile. The least-known species are residents of primary forest, especially in the genera Accipiter, Leucoptemis and Micrastur. Nests remain undescribed for 19 species, and less than five nests have been described for an additional 12 species. No prey data are available for six species and only anecdotal data have been published for a further 25 species. Breeding behaviour is unknown for 27 species and known only anecdotally for an additional 18. The migratory habits of 28 species are poorly understood. Available data permit a reasonable assessment of the conservation status for 39 species and a well-educated guess for another 31, but any assessment for the remaining 11 would be speculation at best.

EVIDENCE OF NOCTURNAL MIGRATION BY OSPREY (PANDION HALIAETUS) IN NORTH AMERICA AND WESTERN EUROPE

ABSTRACT Resumimos y discutimos observaciones recientes de migraciones nocturnas de Pandion haliaetus. En el otoño de 2004, desde la plataforma de observación (elevación 320 m) del edificio Empire State en la ciudad de Nueva York se realizaron dos avistamientos nocturnos de individuos migrando hacia el sur. De igual forma, el monitoreo satelital ha revelado que P. haliaetus migra durante la noche de manera regular tanto en la temporada migratoria de otoño como en la de primavera, particularmente en vuelos largos que implican el cruce de cuerpos de agua. Encontramos que 15 individuos migraron hacia el sur durante la noche en otoño (1) de Carolina del Norte a Florida, (2) de Florida a Cuba y (3) de Cuba a Centroamérica/México o América del Sur. En la migración hacia el norte, dos individuos migraron durante la noche desde Sudamérica hacia Cuba. Algunos de los vuelos sobre agua representaron entre 12–22 horas de vuelo continuo. También proveemos información que muestra que al menos otras 10 especies de rapaces migran durante la noche de manera regular.

Juvenile Osprey Navigation during Trans-Oceanic Migration

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 resolution satellite-monitored GPS track data, we show that juvenile ospreys (Pandion haliaetus) are capable of non-stop constant course movements over open ocean spanning distances in excess of 1500 km despite the perturbing effects of winds and the lack of obvious landmarks. These results are best explained by extreme navigational precision in an exogenous spatio-temporal reference frame, such as positional orientation relative to Earths magnetic field and pacing relative to an exogenous mechanism of keeping time. Given the age (<1 year-old) of these birds and knowledge of their hatching site locations, we were able to transform Enhanced Magnetic Model coordinate locations such that the origin of the magnetic coordinate space corresponded with each birds nest. Our analyses show that trans-oceanic juvenile osprey movements are consistent with bicoordinate positional orientation in transformed magnetic coordinate or geographic space. Through integration of movement and meteorological data, we propose a new theoretical framework, chord and clock navigation, capable of explaining the precise spatial orientation and temporal pacing performed by juvenile ospreys during their long-distance migrations over open ocean.

THE SPRING MIGRATION OF ADULT NORTH AMERICAN OSPREYS

Abstract Most North American Ospreys (Pandion haliaetus) are migratory, breeding in northern latitudes and migrating long distances to and from their wintering grounds in the tropics. Although fall migration patterns of North American Ospreys have been described and studied, very little has been published about the spring migration of these birds. We used satellite telemetry to: (1) determine the characteristics (timing, duration, migratory routes) of spring migrations of Ospreys; (2) determine if differences in spring migration patterns existed between sexes and among three breeding populations (east coast, midwestern, and western); and (3) compare consecutive fall and spring migrations of individual Ospreys. The median dates for departure from the wintering grounds and arrival on the breeding grounds did not differ significantly between adult male and female Ospreys. Compared to their fall migrations, all male and all east coast Ospreys spent fewer days on migration, fewer days in stopover periods along the migration route, traveled shorter distances overall, and traveled farther (on average) each day during spring. In contrast, fall and spring migration characteristics of all female and western Ospreys were similar. Our findings suggest that, although sex and breeding location might influence the spring migration strategy used by individual Ospreys, both males and females minimize the time spent on migration to ensure a timely arrival on the breeding grounds to establish or defend a nesting territory. 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, se ha publicado muy poco sobre la migración primaveral de esta especie. Utilizamos telemetría satelital para: (1) determinar las características (tiempos, duración, rutas migratorias) de la migración primaveral de P. haliaetus; (2) determinar si las diferencias en los patrones de migración primaveral existieron entre sexos y entre tres poblaciones reproductivas (costa este, medio oeste y oeste); y (3) comparar migraciones consecutivas de otoño y primavera de individuos de P. haliaetus. Las fechas medianas de partida desde los sitios de invernada y de arribo a los sitios de reproducción no difirió significativamente entre individuos macho y hembra de P. haliaetus. En comparación con las migraciones otoñales, todos los individuos de P. haliaetus macho y todos los individuos de la costa este emplearon menos días migrando, menos días en periodos de descanso a lo largo de la ruta de migración, viajaron distancias más cortas en general y viajaron más lejos (en promedio) cada día durante la primavera. En contraste, las características migratorias de otoño y primavera de todos los individuos hembra y macho de P. haliaetus fueron similares. Estos hallazgos sugieren que aunque el sexo y la ubicación del sitio de reproducción pueden influir en la estrategia de migración primaveral utilizada por los individuos de P. haliaetus, tanto hembras como machos minimizan el tiempo empleado en la migración para asegurarse un arribo a tiempo a los sitios de reproducción para establecer o defender un territorio de nidada.

Behavioral Conditioning and Techniques for Trapping Barred Owls (Strix Varia)

ABSTRACT Condicionamiento Comportamental y Técnicas para Atrapar a Strix Varia Entrenamos individuos de Strix varia para asociar un silbido o llamado con la provisión de alimento. Esto facilitó enormemente atrapar a las aves, localizar sus nidos y pichones, y reconocer el reemplazo en las parejas reproductivas. Atrapamos 61 lechuzas en un total de 78 veces. Cuarenta y cuatro de las lechuzas habían sido entrenadas antes de su captura. Las trampas bal-chatris (36 capturas) y las redes de niebla colapsables dho-gazas (37 capturas) fueron nuestros métodos preferidos para capturar a las lechuzas. Describimos nuestras técnicas de entrenamiento y de captura como una ayuda para otros estudios sobre S. varia y otras especies de lechuzas, para las cuales sospechamos que éstas técnicas pueden ser aplicables.

Wintering Ecology of Adult North American Ospreys

Abstract 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 duration of wintering period, to examine the characteristics of wintering areas used by Ospreys, and to quantify space use and activity patterns of wintering Ospreys. Adult Ospreys migrated to wintering sites and exhibited high wintering site fidelity among years. Overall, Ospreys wintered on river systems (50.6%) more than on lakes (19.0%), and use of coastal areas was (30.4%) intermediate. Ospreys remained on their wintering grounds for an average of 154 d for males and 167 d for females. Locations of wintering Ospreys obtained via GPS-capable satellite telemetry suggest these birds move infrequently and their movements are very localized (i.e., <5 km from selected roosting areas). Sizes of home ranges and core-use areas for wintering Ospreys averaged 12.7 km2 and 1.4 km2, respectively. Overall, our findings suggest wintering adult North American Ospreys are very sedentary, demonstrating a pattern of limited daily movements and high fidelity to a few select locations (presumably roosts). We suggest this wintering strategy might be effective for reducing the risk of mortality and maximizing energy conservation. Ecología de Invernada de Individuos Adultos de Pandion haliaetus Pandion haliaetus típicamente migra grandes distancias hacia sus sitios de invernada en los trópicos. Más allá de la distribución general del rango de invernada (i.e., el Caribe, América del Sur y América Central), se sabe muy poco sobre la ecología de invernada de esta especie. Utilizamos telemetría satelital para determinar la duración del periodo de invernada, examinar las características de las áreas de invernada utilizadas por P. haliaetus y cuantificar el uso del espacio y los patrones de actividad de individuos de esta especie. Los individuos adultos de P. haliaetus migraron hacia los sitios de invernada y exhibieron una elevada fidelidad por el sitio de invernada entre años. En general, P. haliaetus invernó en sistemas riparios (50.6%) más que en lagos (19.0%) y el uso de zonas costeras fue (30.4%) intermedio. Los individuos de P. haliaetus permanecieron en sus áreas de invernada un promedio de 154 días para los machos y 167 días para las hembras. Las ubicaciones de individuos de P. haliaetus obtenidas vía telemetría satelital GPS sugieren que estas aves se mueven con poca frecuencia y que sus movimientos son muy localizados (i.e., <5 km de las áreas de dormideros seleccionadas). El tamaño de las áreas de hogar y áreas núcleo de uso para invernada en P. haliaetus promedió 12.7 km2 y 1.4 km2 respectivamente. En general, estos hallazgos sugieren que los individuos adultos de P. haliaetus invernantes son muy sedentarios, demostrando un patrón de movimientos diarios limitado y una elevada fidelidad a las ubicaciones seleccionadas (presumiblemente dormideros). Sugerimos que esta estrategia de invernada puede ser efectiva para reducir el riesgo de mortalidad y maximizar la conservación de energía.