Joseph M. Wunderle

The role of animal seed dispersal in accelerating native forest regeneration on degraded tropical lands

This paper reviews the characteristics of animal seed dispersal relevant to tropical forest restoration efforts and discusses their management implications. In many tropical regions seed dispersal by animals is the predominant form of dissemination of propagules and has the potential to facilitate recolonization of native vegetation on degraded sites. The site traits relevant for attracting seed dispersers include the availability of perches, the structural complexity of the vegetation and the presence of food resources, especially fruit, as an attractant. Tree plantations with these traits will be particularly attractive to animal seed dispersers and, therefore, will have higher rates of seed rain than plantations lacking these traits. The efficacy of animal seed dispersal to restoration sites can be limited by the degree of isolation from a seed source, absence of animal seed dispersers in the region and by large seed size. In highly degraded regions, where seed sources may be isolated and animal seed dispersers rare, restoration will require direct seeding or planting. However, even under the best of conditions with a full compliment of animal seed dispersers and a nearby seed source, large-seeded species, because of their relative immobility, should be planted if a full return to primary forest is desired.

Development of floristic diversity in 10-year-old restoration forests on a bauxite mined site in Amazonia

Abstract Patterns of plant and animal diversity were studied in a 10-year-old native species reforestation area at a bauxite-mined site at Porto Trombetas in western Para State, Brazil. Understorey and overstorey floristic composition and structure, understorey light conditions, forest floor development and soil properties were evaluated in a total of 38 78.5-m2 plots located in the reforestation area at varying distances up to 640 m from the boundary with the surrounding primary forest. Wildlife surveys focusing primarily on birds and bats were also conducted to assess the role of seed-dispersing animals in regeneration of woody forest species within the plantations and colonization by primary forest species not included in the original reforestation. Regeneration density, species richness and species diversity (Shannon–Wiener index) for woody perennial species, vines, herbs and grasses were strongly correlated with the diversity of planted tree species and structural development parameters, degree of forest floor development and soil pH. The better developed closed-canopy plots (>40% crown closure) were characterized by relatively well-developed litter (O1) and humus (O2) layers, more acidic soils being typical of the surrounding primary forests, and a more diverse herb, vine and woody perennial flora with a greater representation of primary forest species being characteristic of late secondary forests. In closed-canopy plots a total of 125 tree, palm and shrub species were censused (versus 34 in the more open-canopy plots), of which 75 species are known to have been introduced by natural means from the surrounding primary forest (versus 11 species in the open-canopy plots). Among the plantation plots, there was significant colonization by primary forest woody species up to 640 m away from the primary forest edge, although both the abundance and the diversity of colonizing species declined with increasing distance into the plantations. Smaller-seeded primary forest woody species dispersed by mammals and birds represented a higher proportion of the colonizing species compared with the larger-seeded species. These data are consistent with the results of the wildlife surveys, which indicated that most animal seed dispersal is provided by bats, that the most common frugivorous bat and bird species in the plantations feed on small-seeded plant species and that birds and mammals that typically disperse larger-seeded tree species (such as toucans, trogons, tapirs, deer and primates) are still rare in the reforestation area. These results suggest that while the reforestation program has been successful in creating a favorable environment for regeneration of a native primary forest species, further management interventions, such as enrichment plantings, may be required to accelerate regeneration of large-seeded primary forest species.

Distribution of overwintering nearctic migrants in the Bahamas and Greater Antilles

Point counts and mist nets were used to survey the distribution of nearctic migrant landbirds wintering in 15 habitat types on the islands of Andros, New Providence, and Great Inagua in the Bahamas, and in western Cuba, Jamaica, Dominican Republic, Puerto Rico, and St. John in the Greater Antilles. Of 150 species detected, 23% were overwintering nearctic migrants. Migrants were found at l-7 1% of the points in natural or disturbed habitat (mean = 25%). Distance from North America and island size contributed only 9% of the variation in total migrant abundance among all habitats, reflecting the fact that habitats on the same island often differed substantiallv in suitability. However. distance and island size contributed 48% ofthe variation in total migrant abundance in xeric habitats, indicating that these factors may be important in contributing to migrant abundance within a habitat. Generally, geographically-restricted species were not abundant while most geographically-widespread species were abundant in a wide range of habitats. No consistent relationships were found between the abundance and distribution of migrants and residents, but the two groups did not differ in their degree ofhabitat specialization. Habitat specialization by migrants was rare, with one species restricted primarily to mangroves and another to pine. As found in Yucatan, migrant species that breed in mature temperate-zone forest occurred in both mature forest and second-growth habitats in the winter. However, migrants that breed in early second-growth or edge habitats mostly avoided closed-canopy forests in the Caribbean.

The composition and foraging ecology of mixed-species flocks in pine forests of hispaniola

We determined the flocking propensity of 48 species of birds occurring in native pine forest in the Cordillera Central of the Dominican Republic, and the species composition of 180 mixed-species flocks. Flocks were unusually ubiquitous, with 46 species occurring in at least one flock, 11 species regularly present, and all insectivorous species and all migrant species participating. Most birds encountered were permanent residents, but winter residents (Nearctic migrants) were an important component of the flocks and, as a group, had the highest flocking propensity. Flocks were cohesive and the resident insectivore, the Black-crowned Palm Tanager (Phaenicophilus palmarum) often served as the nuclear species. Censuses suggest species richness within flocks reflects the species present in the habitat, but agonistic interactions indicate that intraspecific aggression may limit the number of individuals of a species in these flocks. Species co-occurrence data indicate that species do not occur independently of one another in flocks. Positive associations were far more common than negative co-occurrences, suggesting mutual habitat dependencies or species interactions within flocks. A non-random association of nearest neighbors also indicated that species may be gaining feeding benefits from flocking by associating as close neighbors with an individual of another species, but we were not able to rule out the possibility that predation is an important selective agent. Intraspecific comparisons of foraging behavior between flocking and solitary birds provides some evidence that individuals modify foraging locations and foraging tactics upon joining mixed-species flocks, and that their foraging behavior tends to converge with the feeding behavior of the nuclear species. An increase in the feeding rate was recorded for one species. These data suggest that at least some species may accrue feeding advantages as flock participants.

Responses of bird populations in a Puerto Rican forest to Hurricane Hugo : the first 18 months

Bird populations in a subtropical wet forest were monitored every two to three weeks with mist nets and point counts beginning two weeks after the passage of Hurricane Hugo in September 1989. The results were compared with those of a pre-hurricane study in the same locations in which birds were sampled in forest understory and openings. Capture rates were initially higher than in the previous study, due to displaced canopy dwellers foraging in the understory. The shift ofcanopy dwellers may have obscured expected declines in nectarivores and fruit/seedeaters and contributed to increased detections of omnivores and insectivores. Bird captures and fruit production peaked 93-156 days after the storm in pre-existing gaps, where higher capture rates and a distinct assemblage of birds occurred in contrast to sites without fruit (forest understory and a powerline opening). Captures in pre-existing gaps decreased as fruit production ceased, and overall captures declined to baseline levels after 198 days. After one year of recovery, new gaps and forest understory became distinguishable on the basis of their unique foliage profiles. Although different bird assemblages had been found in forest understory and in gaps prior to the hurricane, these assemblages lost their distinctiveness after the storm. It may take many years after a hurricane for forest understory and gaps to become sufficiently distinct in structure and resources before birds differentiate between the two habitats.

STATUS OF THE CALIFORNIA CONDOR (GYMNOGYPS CALIFORNIANUS) AND EFFORTS TO ACHIEVE ITS RECOVERY

The Auk, Vol. , Number , pages  . ISSN -, electronic ISSN -.  by The American Ornithologists’ Union. All rights reserved. Please direct all requests for permission to photocopy or reproduce article content through the University of California Press’s Rights and Permissions website, http://www.ucpressjournals. com/reprintInfo.asp. DOI: ./auk.... JEFFREY R. WALTERS,1,7 SCOTT R. DERRICKSON,2 D. MICHAEL FRY,3 SUSAN M. HAIG,4 JOHN M. MARZLUFF,5 AND JOSEPH M. WUNDERLE, JR.6

ANATOMY OF A BOTTLENECK : DIAGNOSING FACTORS LIMITING POPULATION GROWTH IN THE PUERTO RICAN PARROT

The relative importance of genetic, demographic, environmental, and catastrophic processes that maintain population bottlenecks has received little consideration. We evaluate the role of these factors in maintaining the Puerto Rican Parrot (Amazona vittata) in a prolonged bottleneck from 1973 through 2000 despite intensive conservation efforts. We first conduct a risk analysis, then examine evidence for the importance of specific processes maintaining the bottleneck using the multiple competing hypotheses approach, and finally integrate these results through a sensitivity analysis of a demographic model using life-stage simulation analysis (LSA) to determine the relative importance of genetic, demographic, environmental, and catastrophic processes on population growth. Annual population growth has been slow and variable (1.0 ± 5.2 parrots per year, or an average λ = 1.05 ± 0.19) from 16 parrots (1973) to a high of 40–42 birds (1997–1998). A risk analysis based on population prediction intervals (PPI) indi...

Vines and canopy contact: a route for snake predation on parrot nests

Summary Ornithologists have hypothesized that some tropical forest birds avoid snake predation by nesting in isolated trees that do not have vines and canopy contact with neighbouring trees. Here we review two complementary studies that support this hypothesis by demonstrating (1) that an abundance of vines and an interlocking canopy characterized Jamaican Black-billed Parrot Amazona agilis nest-trees that failed due to chick loss, presumably to snakes, and (2) that such trees were used preferentially by an arboreal snake congeneric to the snake implicated in the parrot losses. Evidence strongly suggested that losses of nestling Black-billed Parrots were due in substantial part to predation by the Jamaican (yellow) Boa Epicrates subflavus (Boidae). Studies of the closely related Epicrates inornatus on Puerto Rico revealed that trees used by boas had more vine cover and more crown or canopy contact with neighbouring trees than did randomly selected trees. Moreover, the boas had relatively large home ranges and were most active during March to July, which corresponds with the breeding season of parrots as well as other bird species. We suggest that nest failure due to snakes may be reduced in endangered bird species through isolating the nest-tree by eliminating vines and canopy contact with neighbouring trees and shrubs and by placing barriers on the nest-tree trunk.

KIRTLAND'S WARBLERS IN ANTHROPOGENICALLY DISTURBED EARLY-SUCCESSIONAL HABITATS ON ELEUTHERA, THE BAHAMAS

Abstract. To characterize the nonbreeding habitat of Kirtlands Warbler (Dendroica kirtlandii) on Eleuthera, The Bahamas, we quantified the habitat at sites where we captured the warblers and compared these traits with those of random sites and sites of tall coppice. On the basis of a chronosequence of satellite imagery, 153 capture sites ranged in age from 3 to 28 years after human disturbance, mean 14.6 years ± 6.3 (SD). Capture sites had been abandoned after clearing (65%), converted to goat pasture (26%), burned (2%), or were young second growth following unknown disturbance (7%). Canopies in 104 capture plots were lower (mean 1.8 m) than canopies in random plots (mean 2.7 m) and plots of late-successional tall coppice (mean 6.3 m). At seven sites mean foliage density in capture plots was consistently greatest at 0.5 to 1.0 m height, but the sites were heterogeneous for other foliage-height classes <3 m and for time since disturbance, canopy height, stem density, and five ground-cover traits. Plots did not differ by the sex of the captured bird except for a difference (P = 0.05) in foliage density at heights <3 m. Kirtlands Warblers frequently consumed fruit (69% of 499 observations), especially from Lantana involucrata, Erithalis fruticosa, and Chiococca alba. Foliage of these plants was more abundant in capture plots than random plots. Because the warblers consume fruit extensively and fruit is more abundant in early successional habitat, this species, like other nearctic—neotropical migrants that breed in early successional habitats, is absent from mature forests on the wintering grounds.

Ecological relationships of two todies in Hispaniola : Effects of habitat and flocking

We studied microhabitat use, foraging and social behavior of Broad-billed (Todus subulatus) and Narrow-billed (T. angustirostris) Todies in two areas of sympatry in the Cordillera Central of the Dominican Republic. Solitary Broad-billed and Narrow-billed Todies occupied distinct microhabitats in both shade coffee plantations and native pine forest while generally sharing similar foraging strategies. In both habitats, Broad-billed Todies foraged higher in the vegetation and occurred in more outer horizontal positions with lower foliage density than did their congener. Movement rates and feeding rates differed significantly between the two species, with the Narrow-bill being the more active species. Changes in foraging behavior by both species of todies were observed when they associated with mixed-species flocks in pine forest. We noted a decrease in some measures of spatial overlap of todies in interspecific flocks, but other feeding behaviors tended to converge.