Bergstrom Award Recipients 2000

Pablo Munguia
Universidad de Guadalajara
Guadalajara, México

TITLE: Shorebird diversity and behavior at the Laguna de Chapala and Laguna de Sayula, Mexico related to disturbance and habitat quality.

SUMMARY: The Laguna de Chapala (hereafter referred to as Chapala) and the Laguna de Sayula (hereafter referred to as Sayula) are two important habitats for aquatic birds, either migrant, transitory or resident. Twenty-five species of shorebirds are present in this area, and over 100 species of birds combining aquatic and terrestrial. Chapala is under great environmental disturbance due to anthropogenic activities such as waste disposal, agricultural activities, water extraction, and tourism. Sayula is not as disturbed, however there is an increase of activities in certain areas, such as acuaculture and agricultural activities. The purpose of this project is to assess the seasonal diversity and abundance of the aquatic avifauna and its invertebrate prey diversity. Also, to observe if there are differences in the behavior of birds between sites and between seasons, and relate these, if possible, to habitat quality and environmental disturbance. These studies can provide a basis and reference for future management policies for shorebirds (including Neotropical migrants) in the two Jalisco wetlands. The duration of this project is one year, however there are plans in the future to continue with this research.

Alina Perez Hernandez
Pinar del Rio
Cuba

TITLE: The effect of different land management strategies on the bird communities of the Guanahacabibes Peninsula Biosphere Reserve.

SUMMARY: The Guanahacabibes Peninsula Biosphere Reserve at the western tip of Cuba, with its exceptionally diverse flora and fauna, is one of the best protected areas on the island. Because of the various uses of the natural resources and the expected increase in tourism in the reserve, there is a need for a thorough evaluation of the natural resources as well as detailed information and scientific backing to evaluate the land management activities and offer alternative sustainable options. We propose establishing the continual monitoring of resident and migratory birds of the biosphere reserve and evaluating the different management strategies according to identified ecological indicators. We will also focus on the behavior of the migratory species and their use of resources during their time in Guanahacabibes. There will be work done to educate the communities associated with this area, regarding the project and its results.

SUMMARY: Life history studies are the basis for any other biological study of any species. The Curl-crested jay (Cyanocorax cristatellus) is an endemic bird from the Brazilian savannas that lives in groups and has well - developed social behaviors. This study will be conducted at Parque Nacional de Brasilia, a 32000 ha conservation unit in the "cerrado" of central Brazil.

The main purpose of the project is to investigate behavior and life history traits of C. cristatellus groups, and will focus upon territory and group size, foraging and sentinel behaviors, and breeding system. Individuals will be captured with mist nets and traps and marked with metallic and colored plastic bands. Individuals will be weighed and measured (tarsus, beak, wing and total length), and blood will extracted. Focal samples will be taken during wet and dry seasons to record the bird's activity specially in relation to foraging and sentinel behaviors. From these observations a harvest rate will be calculated. Reproduction aspects will be verified. This includes nest description, nest attendance by helpers and/or parents, food items and frequency of delivery to the nest and nestlings' development and growth by measuring nestlings' weight, tarsal, wing and beak lengths every two days.

C. cristatellus has never received special attention concerning its life history neither to its behavior. The study of C. cristatellus social system will provide new insights into the ecological attributes associated with the evolution of sociality of the family in general.

SUMMARY: Declines in populations of migratory birds may be a result, in part, of low juvenile survival. Data on postfledging dispersal and survival of migratory birds are scarce. Ecological requirements of juveniles during the postfledging period must be understood in order to manage habitat effectively for species of conservation concern. Here, I request funding to evaluate postfledging dispersal and survival of Yellow-breasted Chats (Icteria virens) in the Ouachita Mountains of southwestern Arkansas. My proposed project will address the following research questions: 1) What patterns of movement do juvenile Yellow-breasted Chats exhibit during the postfledging period? 2) Do requirements of postfledging habitat differ from those of breeding habitat? 3) Does natal habitat patch size have an affect on postfledging dispersal of Yellow-breasted Chats? and 4) Does natal habitat patch size have an affect on survival of Yellow-breasted Chats during the postfledging period? Proposed methods include using radio telemetry to track juvenile chats from natal habitat to postfledging habitat. Survival rates of fledglings will be estimated using MICROMORT. I will compare dispersal distances, movement patterns, and survival rates of juveniles between small natal habitat patches (0.4-2.0 ha) and large patches (12-20 ha). I will also estimate and compare postfledging home range size for juveniles between small and large natal habitat patches. At this time, there are no data available on postfledging dispersal and survival of Yellow-breasted Chats. Because of recent population declines, postfledging dispersal data are imperative to evaluate the effects of different land management practices on the survival of chats and other migratory birds. The proposed study will begin approximately on 10 May 2000, and will be completed by 31 January 2002. Declines in populations of migratory birds may be a result, in part, of low juvenile survival. Data on postfledging dispersal and survival of migratory birds are scarce. Ecological requirements of juveniles during the postfledging period must be understood in order to manage habitat effectively for species of conservation concern. Here, I request funding to evaluate postfledging dispersal and survival of Yellow-breasted Chats (Icteria virens) in the Ouachita Mountains of southwestern Arkansas. My proposed project will address the following research questions: 1) What patterns of movement do juvenile Yellow-breasted Chats exhibit during the postfledging period? 2) Do requirements of postfledging habitat differ from those of breeding habitat? 3) Does natal habitat patch size have an affect on postfledging dispersal of Yellow-breasted Chats? and 4) Does natal habitat patch size have an affect on survival of Yellow-breasted Chats during the postfledging period? Proposed methods include using radio telemetry to track juvenile chats from natal habitat to postfledging habitat. Survival rates of fledglings will be estimated using MICROMORT. I will compare dispersal distances, movement patterns, and survival rates of juveniles between small natal habitat patches (0.4-2.0 ha) and large patches (12-20 ha). I will also estimate and compare postfledging home range size for juveniles between small and large natal habitat patches. At this time, there are no data available on postfledging dispersal and survival of Yellow-breasted Chats. Because of recent population declines, postfledging dispersal data are imperative to evaluate the effects of different land management practices on the survival of chats and other migratory birds.

SUMMARY: Legislation requires developers to provide habitat compensation, such as creation, for wetlands they destroy. As wetland creation gains popularity, the need for research grows, both to ensure that created wetlands are providing meaningful replacements for the biological functions of destroyed wetlands and to make management recommendations for improvements. To assess the success of created non-tidal, hardwood wetlands in Southern Virginia I will compare the avian communities of the created wetlands to those of natural wetlands logged at the time of wetland creation. A pilot study determined species richness and avian density to be significantly higher on the natural, logged wetlands. However, it was unclear whether these differences were due to the larger size and higher quality surroundings of the natural wetlands or the fact that human-created wetlands are inherently inferior as bird habitat. Avian community data will be gathered using a systematic point count survey and data analyzed to account for differences in detectability between species and sites. Vegetation will be assessed to help explain differences found between sites. Avian densities, species richness, and numbers of certain indicator species will be compared between created and natural sites of the same age to determine the success of forested wetland creation. General trends in avian community development will be determined for a range of sites (1-25 years old) to produce a tool for assessing the success of maturing created forested wetlands. This project aims to use birds as ecological indicators to assess the success of created forested wetlands relative to natural wetlands of the same successional age and to develop a predictive trajectory of avian use for gaging the success of individual created wetlands.

SUMMARY: Transient songbirds often stopover in small isolated oak hammocks that are interspersed among the marshes of coastal South Carolina and Georgia. We tested whether the use of these hammocks by migrants is influenced by the size of the hammock or the structure of the habitat. During both spring and fall migration, the total number of Neotropical migrant species (range in spring: 12-27, fall: 12-21) and mean number of Neotropical migrant individuals recorded per day (range in spring: 3.1-11.3, fall: 5.9-32.9) varied significantly among eight hammocks at the Savannah National Wildlife Refuge, Jasper Co., South Carolina. In addition, a significant positive relationship was found between area and the total number of species and mean number of Neotropical individuals recorded per day during both spring and fall migration. Although more individuals and species were found in larger hammocks, smaller hammocks had a higher density of migrants. Hammocks differed significantly in overall tree and shrub density, but variation in the number of species and abundance of individuals was unrelated to habitat. In conclusion, the size of oak hammocks appears more important to migrant songbirds than the structure of the habitat.

SUMMARY: Little is known about the habitat requirements and survival of neotropical migratory birds during the period between fledging and migration. Most breeding success studies end when young fledge, so the survival rates of young to independence and to migration are virtually unknown. Juvenile survival is essential demographic information, used in calculations of population trends and annual recruitment. In addition, juvenile neotropical migrants may require specific habitats that might differ from that needed by adults of the species for breeding. The habitat selected by juveniles during this period may be critical to their survival, perhaps by 1) helping them avoid predation and 2) providing a ready food source that minimizes starvation and helps build fat reserves for migration. Therefore, identifying and ensuring availability of any such habitats may be important for long-term species survival. No study has examined post-fledging habitat use and survival of shrub-nesting neotropical migrants, although many of these species are declining. We propose a radio-telemetry study of post-fledging habitat use and survival of two shrub-nesting neotropical migrants, the Yellow-breasted Chat (Icteria virens) and the Gray Catbird (Dumetella carolinensis). Results of the study will: 1) provide estimates of juvenile survival rates, which will aid in the estimation of avian population trends, and 2) provide land managers with information on the habitats used, and possibly required, by juvenile neotropical migrants for survival.

SUMMARY: The destruction and fragmentation of tropical forests, which contain the most complex ecosystems on Earth, has become the single greatest threat to global biodiversity. Critical to the maintenance of this biodiversity, is the ability of individuals to move among patches of remaining habitat, but little is known about how animals move in fragmented landscapes and how this movement is affected by changes to landscape configuration over time. This project employs innovative field methods to collect detailed information about the precise movement of forest-dependent birds that will be compared with geographic information about land cover changes in the tropical dry forests of Costa Rica. By combining this information in a spatially explicit simulation model, I aim to predict the impact further deforestation will have on the movement of forest dependent animals, thus advancing a general understanding of the landscape features needed to maintain avian biodiversity in fragmented habitats in this and several other tropical forest regions.

SUMMARY: Swainson's Warblers (Limnothlypis swainsonii) have declined significantly over the last decade, along with 109 other species of Neotropical migrants. As a result, they are a high conservation concern in the Southeast and in need of management and monitoring attention. Management for this species is difficult due to their incomplete life history. Additional information is needed to determine the most effective management strategies. Our objective is to accumulate breeding biology information to allow for future management research. We have been studying a population of Swainson's Warblers in a South Carolina riparian corridor for the last four breeding seasons (1997-2000). We have successfully banded 185 birds, mapped 93 territories, and discovered a record number of active nests (n=44). Preliminary findings suggest processes unknown to SWWA to be occurring, such as cooperative breeding and double brooding. Continued long term monitoring of this marked population could provide valuable demographic information. In addition, we have a rare opportunity to uncover insights into a poorly understood bird.