Beta Diversity and Endemism: Implications for Tropical Reserve Design.
Jill Jankowski, Department of Biological Sciences, Purdue University

Understanding the spatial organization of species diversity and the distribution of threatened species is crucial to designing reserves that maximize the protection of biodiversity. Montane regions of Costa Rica and Panamá offer high species diversity across a habitat mosaic and contain some of the highest levels of endemism in the world. Our previous censuses of bird species on the Pacific slope of the Tilarán range in Monteverde, Costa Rica have shown high local (alpha) diversity and high integrity of species composition within altitudinal zones, yet high between-habitat (beta) diversity across short elevational distances. Regionally endemic species, which are concentrated at higher elevations within our dataset, appear to have narrower altitudinal distributions and lower abundance within their habitats compared to widespread related species ("Brown’s hypothesis"). This suggests a syndrome of vulnerability for endemics by rarity on all scales, making them more endangered than indicated by current classifications.

I propose to significantly expand research in the Tilarán range to include collaboration with botanists, ornithologists, and biogeographers. Using census data for birds over a mapped 20km2 study area, we will quantify beta diversity at short altitudinal intervals across four Holdridge Life Zones. Distributions of plant species along this gradient (provided by William Haber from 500 established points) will be used to determine, using ordination techniques, whether beta diversity is constant with altitude and consistent between plants and birds. Additionally, we will quantify the altitudinal distribution of 20 regionally endemic species and 40 closely related cosmopolitan species on the Atlantic and Pacific slopes of the Monteverde Reserve. Using the correlation between geographic range size and estimated local population size, we will fully test Brown’s hypothesis that endemic species are local habitat specialists. This hypothesis has been widely discussed but poorly tested with accurate quantification of range size, habitat distribution, and local abundance, especially in the tropics.

This project will succeed in defining the limits of species’ distributions over altitudinal distance and quantifying the resulting variation in community composition, both of which are critical components for designing reserve areas that offer adequate protection for biodiversity. This work will also quantify the return on investment in species protection for extending reserve boundaries to cover a wider spectrum of habitats. In addition, our quantitative measure of Brown’s hypothesis will indicate the correlation of rarity on local and regional scales for endemic species and lay the groundwork for future studies on habitat selection that will aid in better understanding the biology of these species.

Response of grassland songbirds to management practices in native prairies of the Loess Hills, Iowa. Tracy Walker, Iowa State University

Habitat loss and fragmentation are often related to the decline of grassland bird populations. Fragmentation can strongly influence bird communities within grasslands and may account for variation in species richness and abundance among landscapes. Encroachment of woody vegetation as the result of fire suppression may also fragment grasslands, and in turn negatively impact reproductive success of grassland songbirds. Prescribed burning is a current technique that has been proposed to reduce the spread of woody vegetation in prairies. Grassland songbird response in past studies using burning has demonstrated a general pattern of avoidance in the first year after a burn, followed by a peak in habitat use 2-4 years post-burn, then a tapering off of habitat use after 5 years or more post-burn. Fire suppression beginning from the time of European settlement in the mid-1800’s has led to the loss and fragmentation of contiguous prairie in the unique Loess Hills landform as shown by invasion of woody vegetation. If the Loess Hill prairies are to be successfully restored and conserved, it is worthwhile to gauge the influence of fire and other currently used clearing methods in grasslands, and how those resulting changes (e.g., changes in vegetation structure) impact the birds that use prairie remnants. This research will assist managers of prairie landscapes within the Loess Hills in finding prescribed burn and other management regimes that are optimal for maintaining grassland songbird habitat use. This study proposes to investigate: (1) how restoration efforts to prevent woody vegetation encroachment affect prairie vegetation structure; (2) how this, in turn, affects the habitat use by the wildlife community, specifically relative abundance, species diversity, and nesting success of grassland songbirds; and (3) how the surrounding landscape influences habitat use and nesting success. I intend to answer these questions by quantifying songbird habitat use across a gradient of grasslands with various fire histories (i.e., number of years post burn). These grasslands will be within adjacent landscapes with varying proportions of woody vegetation, from none to complete forest, within areas representative of the Loess Hills, in particular Broken Kettle Preserve and Five Ridge Prairie in Plymouth county, Iowa. Habitat use and nesting success of breeding grassland songbirds will be determined using point count censuses and nest searching and monitoring, respectively.

Use of stable hydrogen isotopes to identify and assess yearly variation of natal origins among raptors migrating through the Florida Keys. Sara Ress, University of Arkansas-Fayetteville

Breeding and wintering areas for many migratory raptors have yet to be linked, and little is known about origins of birds in migration. I will use stable isotopes of hydrogen (deuterium) in feathers to determine latitudinal origins of immature birds of 6 raptor species captured in fall during 6 years in the Florida Keys. To date, no study has used stable isotopes to examine multiple species of raptors at one banding site and no study has examined annual variation in source populations through a migratory pathway like the Keys. By analyzing feathers collected from the entire breeding range of 6 focal species, I will create a predictive deuterium model for comparison with isotopic values from birds sampled in the Keys to determine annual variation in latitudinal origins. Currently source areas for raptors that migrate through the Keys remain largely unknown and virtually nothing is known about annual variation in origins of migrating raptors.

Fluctuating asymmetry in golf course birds: evidence of development stress from pesticides. Josh LeClerc, College of William & Mary

Habitat loss, largely due to human development, is causing a decline in bird populations. An increasingly common form of development is the construction of golf courses. As native habitat is converted into golf courses, the question is raised as to whether golf courses can replace the lost ecosystem functions. One concern is that chemical pesticides and fertilizers used on golf courses could have detrimental effects on bird development and growth. These effects can be quantified by measuring fluctuating asymmetries, or deviations from perfect symmetry in bilateral traits. I will examine levels of fluctuating asymmetry in eastern bluebirds breeding on and off golf courses.

Spatial variation in reproductive output of a song sparrow (Melospiza melodia) metapopulation. Scott Wilson, University of British Columbia

A key issue in population ecology is the influence of spatial structure on the dynamics and persistence of populations. It is often assumed that a group of local populations will follow a classical metapopulation structure with asynchronous population fluctuations and rescue of declining populations through dispersal. However, recent studies provide examples of sub-populations that vary more or less synchronously, thus reducing the likelihood of demographic rescue. Although these studies aid our understanding of the degree to which sub-populations fluctuate in synchrony, few have been able to measure the strength of mechanisms promoting synchrony among populations or determined how these mechanisms influence reproduction and survival to promote population change. I propose to examine the extent of spatial and temporal variation in reproductive output in 8 populations of song sparrows (Melospiza melodia) that reside year-round on islands in the Haro Strait, British Columbia. I will also attempt to identify the mechanisms that affect the degree of synchrony in reproductive success across populations. Previous studies on the Mandarte Island population show that annual timing of breeding is influenced by the El Niño Southern Oscillation with earlier breeding in warmer El Niño years and later breeding in colder La Niña years. With earlier breeding, females complete more successful nesting attempts and achieve higher reproductive output. Because climate operates at a regional scale, it is possible that the timing of breeding across all populations in this system is synchronized by the El Niño cycle, and that synchrony in annual breeding success also occurs. However, preliminary analyses also show that the rate of nest predation and brood parasitism by brown-headed cowbirds (Molothrus ater) varies markedly among study populations that differ in proximity to the mainland. Variation in parasitism and nest predation may promote asynchrony in reproductive success across populations, and potentially over-ride the effects of climate. Thus, the degree to which reproductive output varies synchronously across populations will depend on the relative strengths of each of these mechanisms.

The effects of forest fragmentation on post-fledging survival and dispersal of a forest songbird. Scott A. Rush, York University-Ontario

Many studies have addressed the effects of forest fragmentation on the breeding behavior and fecundity of forest songbirds but have left the critical dynamics of the post-fledging period largely understudied. Using radio-telemetry I tracked adult hooded warblers (Wilsonia citrina) attending fledglings from nests within large (>100ha), and small (<5ha) forest fragments during the summer of 2002 (the first year of a two year study). I used Kaplan-Meier and Cormack-Jolly-Seber models to test for the effects of forest fragment size, sex and age of the attending adult, fledge date and brood size on the survival of the young during the ~4 weeks post-fledging, and prior to cessation of parental care. Habitat use was examined in relation to the sex of the attending adult and forest fragment size. I found fledgling survival did not differ between large and small forest fragments but was influenced by the sex and age of the attending adult. Nesting habitat was structurally similar to that used during the post-fledging period while neither forest fragment size nor sex of the attending adult were influential on post-fledgling habitat use. While results of this study suggest that forest fragmentation does not overtly affect the post-fledging survival and habitat use of hooded warblers, many songbird species do not use similar habitat throughout the nesting and post-fledging period and as a result of the physiognomic effects associated with forest fragmentation these species may face limitations in the availability of critical resources during the post-fledging period. As such, the effects of forest fragmentation on fledgling survival, as influenced by the availability of habitat and the demography of the adults must be considered during the development of conservation plans for neotropical migrant songbirds.

Educational Bird Banding Station in the Alvarado Wetlands, Veracruz. Octavio Cruz, Wetland Conservation Program, Pronatura Veracruz.

The funds provided by AFO for this project will be used as a compliment for the acquisition of part of the equipment for the banding station, its operation and maintenance and for all of the environmental education activities leaded in schools and at the site during 2003. This study will be done as part of the “Alvarado Wetlands Conservation Program”, which has been financed by Pronatura Veracruz, as part of a more wide conservation initiative.

The main migration corridor in Mexico consist of a vast extension of shoreline, coastal plain and mountain regions in the central and south-central part of the state of Veracruz. These region is crucial for neotropical migrants (especially Passerines) as they mirgrate through southern Mexico into Central America. These corridor is particularly valuable due to their diversity of migratory wintering species and important resident species (Cruz 1994), (Cruz 1999).

The communities of the Alvarado wetlands lives closely related with their environment; although, the lack of information have produced loss of habitat and over exploitation of natural resources. The environmental education efforts planned in this initiative ensures that the teachers and students of local schools will acquire knowledge and comprehension on their environment, and subsequently the information will reach the inhabitants, in order to develop their sense of respect and owner ship, which in the short term will lead into better and harmless use of the natural resources of the wetland system.

The objectives of establishing a land bird population monitoring and banding station in the Alvarado Wetlands, specifically in Paso Salinas are: