National Aviary

Pittsburgh, PA, United States

National Aviary

Pittsburgh, PA, United States
Time filter
Source Type

Heberling J.M.,University of Tennessee at Knoxville | Brouwer N.L.,National Aviary | Kalisz S.,University of Tennessee at Knoxville
AoB PLANTS | Year: 2017

Overabundant generalist herbivores can facilitate non-native plant invasions, presumably through direct and indirect modifications to the environment that affect plant performance. However, ecophysiological mechanisms behind ungulate-mediated plant invasions have not been well-studied. At a long-term Odocoileus virginianus (white-tailed deer) exclusion site in a temperate deciduous forest, we quantified deer-mediated ecophysiological impacts on an invasive biennial Alliaria petiolata (garlic mustard) and two palatable native herbaceous perennials, Maianthemum racemosum and Trillium grandiflorum. In mid-summer, we found that leaf-level light availability was higher in unfenced areas compared with areas fenced to exclude deer. Alliaria in unfenced areas exhibited 50% higher mean maximum photosynthetic rates compared with fenced areas. Further, specific leaf area decreased by 48% on average in unfenced areas, suggesting leaf structural responses to higher light levels. Similarly, Maianthemum had 42% higher mean photosynthetic rates and 33% decreased mean specific leaf area in unfenced areas, but these functional advantages were likely countered by high rates of deer herbivory. By contrast, Trillium exhibited significantly lower (26 %) maximum photosynthetic rates in unfenced areas, but SLA did not differ. Deermediated differences in light saturated photosynthetic rates for all three species were only significant during months with overstory tree canopy cover, when light availability in the herb layer was significantly lower in fenced areas. Alliaria's enhanced photosynthetic rates implicate overabundant deer, a situation that is nearly ubiquitous across its invaded range. Collectively, our results provide empirical evidence that generalist herbivores can alter non-native plant physiology to facilitate invasion. © The Authors 2017.

Sly N.D.,Cornell University | Townsend A.K.,Cornell University | Rimmer C.C.,Vermont Center for Ecostudies | Townsend J.M.,New York University | And 2 more authors.
Molecular Ecology | Year: 2011

With its large size, complex topography and high number of avian endemics, Hispaniola appears to be a likely candidate for the in situ speciation of its avifauna, despite the worldwide rarity of avian speciation within single islands. We used multilocus comparative phylogeography techniques to examine the pattern and history of divergence in 11 endemic birds representing potential within-island speciation events. Haplotype and allele networks from mitochondrial ND2 and nuclear intron loci reveal a consistent pattern: phylogeographic divergence within or between closely related species is correlated with the likely distribution of ancient sea barriers that once divided Hispaniola into several smaller paleo-islands. Coalescent and mitochondrial clock dating of divergences indicate species-specific response to different geological events over the wide span of the island's history. We found no evidence that ecological or topographical complexity generated diversity, either by creating open niches or by restricting long-term gene flow. Thus, no true within-island speciation appears to have occurred among the species sampled on Hispaniola. Divergence events predating the merging of Hispaniola's paleo-island blocks cannot be considered in situ divergence, and postmerging divergence in response to episodic island segmentation by marine flooding probably represents in situ vicariance or interarchipelago speciation by dispersal. Our work highlights the necessity of considering island geologic history while investigating the speciation-area relationship in birds and other taxa. © 2011 Blackwell Publishing Ltd.

Ricklefs R.E.,University of Missouri-St. Louis | Outlaw D.C.,Mississippi State University | Svensson-Coelho M.,University of Missouri-St. Louis | Svensson-Coelho M.,University of Sao Paulo | And 3 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2014

The malaria parasites (Apicomplexa: Haemosporida) of birds are believed to have diversified across the avian host phylogeny well after the origin of most major host lineages. Although many symbionts with direct transmission codiversify with their hosts, mechanisms of species formation in vector-borne parasites, including the role of host shifting, are poorly understood. Here, we examine the hosts of sister lineages in a phylogeny of 181 putative species of malaria parasites of New World terrestrial birds to determine the role of shifts between host taxa in the formation of new parasite species. We find that host shifting, often across host genera and families, is the rule. Sympatric speciation by host shifting would require local reproductive isolation as a prerequisite to divergent selection, but this mechanism is not supported by the generalized host-biting behavior of most vectors of avian malaria parasites. Instead, the geographic distribution of individual parasite lineages in diverse hosts suggests that species formation is predominantly allopatric and involves host expansion followed by local host-pathogen coevolution and secondary sympatry, resulting in local shifting of parasite lineages across hosts.

Tinoco B.A.,State University of New York at Stony Brook | Astudillo P.X.,University of Azuay | Latta S.C.,National Aviary | Strubbe D.,University of Antwerp | Graham C.H.,State University of New York at Stony Brook
Biotropica | Year: 2013

Human-induced alteration of habitat is a major threat to biodiversity worldwide, especially in areas of high biological diversity and endemism. Polylepis (Rosaceae) forest, a unique forest habitat in the high Andes of South America, presently occurs as small and isolated patches in grassland dominated landscapes. We examine how the avian community is likely influenced by patch characteristics (i.e., area, plant species composition) and connectivity in a landscape composed of patches of Polylepis forest surrounded by páramo grasslands in Cajas National Park in the Andes of southern Ecuador. We used generalized linear mixed models and an information-theoretic approach to identify the most important variables probably influencing birds inhabiting 26 forest patches. Our results indicated that species richness was associated with area of a patch and floristic composition, particularly the presence of Gynoxys (Asteraceae). However, connectivity of patches probably influenced the abundance of forest and generalists species. Elsewhere, it has been proposed that effective management plans for birds using Polylepis should promote the conservation of mature Polylepis patches. Our results not only suggest this but also show that there are additional factors, such as the presence of Gynoxys plants, which will probably play a role in conservation of birds. More generally, these findings show that while easily measured attributes of the patch and landscape may provide some insights into what influences patch use by birds, knowledge of other factors, such as plant species composition, is essential for better understanding the distribution of birds in fragmented landscapes. © 2013 Association for Tropical Biology and Conservation Inc.

Latta S.C.,National Aviary | Ricklefs R.E.,University of Missouri-St. Louis
Journal of Avian Biology | Year: 2010

We used PCR to screen for the presence of haemosporidian parasites (Phylum: Apicomplexa; Order: Haemosporida) in avian blood samples, and sequenced the parasite mitochondrial cytochrome b gene from infected hosts, to study patterns in the prevalence of haemosporidians in 1,166 individuals of 50 species in four habitats along an elevation gradient in the Sierra de Bahoruco, Dominican Republic, island of Hispaniola. We found an overall prevalence of 0.44 among species with ≥10 individuals sampled per year, but this varied considerably among species. We found no difference in infection rates between years, between males and females, between second-year (<1y old) and older birds, or among members of different foraging guilds. Prevalence differed significantly among migratory, endemic resident, and non-endemic resident species, with endemics having the highest rates of infection. Prevalence also varied among habitats, decreasing with increasing elevation, but the pattern was confounded by variation in the host species present at each elevation. From 215 sequenced parasites from 171species of avian hosts, we recovered multiple examples of 12 lineages of Haemoproteus (Parahaemoproteus), two lineages of a Columbiformes-specific clade of H. (Haemoproteus), and 10 lineages of Plasmodium, with an additional seven lineages sampled only once. A single parasite lineage was responsible for 34.4% of all infections, but five more lineages made up 41.8% of all infections. Several lineages were broadly distributed across multiple host species, but six lineages, all H. (Haemoproteus) or H. (Parahaemoproteus), were recorded from at least five individuals of a single host, suggesting host specialization. The number of host species from which each parasite lineage was recovered varied from one to nine; several host species harbored as many as 5-9 parasite lineages. Longitudinal data suggest that while hosts might harbor the same parasite lineage for more than a year, some hosts appear to clear infections from their circulating blood, while others manifested infections by a different parasite lineage. © 2010 The Authors. Journal compilation © 2010 Journal of Avian Biology.

Ricklefs R.E.,University of Missouri-St. Louis | Dodge Gray J.,University of Missouri-St. Louis | Latta S.C.,National Aviary | Svensson-Coelho M.,University of Missouri-St. Louis
Journal of Avian Biology | Year: 2011

We compared the haemosporidian parasite faunas (Plasmodium and Haemoproteus) of small land birds on the islands of St Lucia, St Vincent and Grenada in the southern Lesser Antilles. The islands differ in distance from the South American source of colonists, proximity to each other, and similarity of their avifaunas. On each island, we obtained 419-572 blood samples from 22-25 of the 34-41 resident species. We detected parasite infection by PCR and identified parasite lineages by sequencing a portion of the mitochondrial cytochrome b gene. Parasite prevalence varied from 31% on St Lucia to 22% on St Vincent and 18% on Grenada. Abundant parasite lineages differed between the three islands in spite of the similarity in host species. As in other studies, the geographic distributions of the individual parasite lineages varied widely between local endemism and broad distribution within the West Indies, including cases of long-distance disjunction. St Vincent was unusual in the near absence of Plasmodium parasites, which accorded with low numbers of suitable mosquito vectors reported from the island. Parasites on St Vincent also tended to be host specialists compared to those on St Lucia and Grenada. Similarity in parasite assemblages among the three islands varied in parallel with host assemblage similarity (but not similarity of infected hosts) and with geographic proximity. Parasite prevalence increased with host abundance on both St Lucia and St Vincent, but not on Grenada; prevalence did not vary between endemic and more widespread host species. In addition, the endemic host species harbored parasites that were recovered from a variety of non-endemic species as well. These results support the individualistic nature of haemosporidian parasite assemblages in evolutionarily independent host populations. © 2011 The Authors.

Fahey A.L.,Purdue University | Ricklefs R.E.,University of Missouri-St. Louis | Latta S.C.,National Aviary | DeWoody J.A.,Purdue University
Evolutionary Biology | Year: 2012

Islands offer unique opportunities for studies of evolution and historical demography. We hypothesized that wintering North American migrant bird species would show genetic evidence of population expansion over recent millennia due to the expansion of their breeding distributions following the retreat of the Laurentide ice sheet. In contrast, we presumed that non-migratory species would exhibit more stable historical demographies. We used mtDNA sequences from 649 individuals of 16 avian species on the Caribbean island of Hispaniola to test this prediction. Mismatch distributions did not differ significantly between migrants and non-migrants. However, neutrality indices indicated population expansion in the migrant species, as well as two non-migratory resident species with extensive distributions. Evidence of population expansion was less consistent in other non-migratory residents. We infer that climate prior to the Last Glacial Maximum significantly reduced effective population sizes of most migratory North American bird populations and some resident Hispaniolan bird populations. Our data further revealed that mismatch statistics were poorly correlated with and less informative than the neutrality test statistics, a consideration for future demographic studies. © 2012 Springer Science+Business Media, LLC.

Katzner T.E.,National Aviary | Ivy J.A.R.,Purdue University | Bragin E.A.,Naurzum National Nature Reserve | Milner-Gulland E.J.,Imperial College London | Dewoody J.A.,Purdue University
Animal Conservation | Year: 2011

Estimating population size is central to species-oriented conservation and management. However, in spite of recent development in monitoring protocols, there are gaps in our ability to accurately and quickly estimate numbers of individuals present, especially for the cryptic and often non-breeding components of structured vertebrate populations. Yet knowing the size and growth trajectory of all stage classes of a population is critical for species conservation. Here we use data from 2 years of non-invasive genetic sample collection from the cryptic, non-breeding component of an endangered bird of prey population to evaluate the impact of variability in population estimates on demographic models that underpin conservation efforts. A single non-invasive sample collection in 2003 conclusively identified 47 individual non-breeding imperial eagles, 2.8 times more than were visually counted. In 2004, our comprehensive genetic and observational analyses determined that 414 imperial eagles (n=308 non-breeders+68 territory holders+38 chicks) were present. This estimate was 326% larger than the 127 birds visually observed (n=21 non-breeders+68 territory holders+38 chicks) and 265% larger than the population size predicted by demographic models with the same number of breeders (n=156±7.2;±se). Our study builds on a body of work that demonstrates that conventional visual estimation of cryptic components of structured populations may not always be effective. Furthermore, we show that reliance on those estimates can result in inaccuracies in the demographic models that are often the foundation for subsequent conservation action. © 2011 The Authors. Animal Conservation © 2011 The Zoological Society of London.

Latta S.C.,National Aviary | Latta K.N.,University of Wyoming
Wilson Journal of Ornithology | Year: 2015

Ground-nesting Common Nighthawks (Chordeiles minor), adapted to living and reproducing in North American cities, nest on flat-topped gravel roofs. But populations of Common Nighthawks have declined in recent years throughout their range. One hypothesis to explain these declines is that American Crows (Corvus brachyrhynchos), which have increased dramatically in numbers in urban areas in recent years, may be depredating nighthawk nests. If urban crows are a factor in nighthawk declines, we predicted there would be higher rates of predation on nests in urban areas than in rural areas. We tested this hypothesis by placing and monitoring artificial nests containing Coturnix quail eggs in both urban and rural settings. Depredation of experimental clutches was significantly lower in rural, natural habitats than in the urban environment. The type of substrate on urban roofs may also be important in influencing rates of depredation, as egg-loss was more common at experimental nests on roofs with a small pea gravel substrate than on roofs covered in larger river stone. In all cases, identified predators were American Crows. While experimental predation rates may not represent actual levels of predation on natural nests, these relative differences in rates of predation suggest that urban crows may be an important contributor to declining populations of Common Nighthawks. © 2015 The Wilson Ornithological Society.

News Article | April 1, 2016

The baby Linnaeus sloth, which is a mammal and is related to anteaters, arrived at the aviary a few months ago after being flown from Florida, where he was born to a private breeder. Valentino has been hand raised to be comfortable around people and will be part of the aviary's education programs about rainforest species and their disappearing habitat. "He gives us a chance to talk about the needs of protecting the environment and the rainforest," said Robin Weber, the director of marketing and communication at the National Aviary. The Linnaeus sloth is found in the rainforests of South America. Adults weigh between 10 to 20 lbs (4 to 9 kg).

Loading National Aviary collaborators
Loading National Aviary collaborators