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- Birds (7)
- Shrubland (3)
- Thicket (3)
- Bird populations (2)
- Forest fragmentation (2)
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- Forest interior (2)
- Forests (2)
- Grassland (2)
- Warbler (2)
- Aggressive behavior; comparative study; Connecticut; food availability; human disturbance; nesting success; Pandion haliaetus; Pandionidae; predation impact; prey availability; reproduction; productivity; reproductive success; sibling aggression; Osprey (1)
- Area sensitivity; Blue-winged Warbler; Clearcuts; Early successional birds; Habitat fragmentation; Landscape context; Shrubland birds (1)
- BROWN-headed cowbird (1)
- Beaver (1)
- Bird (1)
- Bird behavior (1)
- Bird community (1)
- Bonferroni Method (1)
- Breeding birds (1)
- Clearcuts (1)
- Community assembly (1)
- Corridor (1)
- DENDROICA (1)
- Disturbance (1)
- EMBERIZIDAE (1)
- Early successional habitat (1)
- Eastern grasslands (1)
- Ecology (1)
- Edge effect (1)
- False Discovery Rate (1)
- Foraging (1)
Articles 1 - 21 of 21
Full-Text Articles in Life Sciences
Positive Relationships Between Association Strength And Phenotypic Similarity Characterize The Assembly Of Mixed-Species Bird Flocks Worldwide, Hari Sridhar, Umesh Srinivasan, Robert A. Askins, Julio Cesar Canales-Delgadillo, Chao-Chieh Chen, David N. Ewert, George A. Gale, Eben Goodale, Wendy K. Gram, Patrick J. Hart, Keith A. Hobson, Richard L. Hutto, Sarath W. Kotagama, Jessie L. Knowlton, Tien Ming Lee, Charles A. Munn, Somchai Nimnuan, B. Z. Nizam, Guillaume Péron, V. V. Robin, Amanda D. Rodewald, Paul G. Rodewald, Robert L. Thomson, Pranav Trivedi, Steven L. Van Wilgenburg, Kartik Shanker
Positive Relationships Between Association Strength And Phenotypic Similarity Characterize The Assembly Of Mixed-Species Bird Flocks Worldwide, Hari Sridhar, Umesh Srinivasan, Robert A. Askins, Julio Cesar Canales-Delgadillo, Chao-Chieh Chen, David N. Ewert, George A. Gale, Eben Goodale, Wendy K. Gram, Patrick J. Hart, Keith A. Hobson, Richard L. Hutto, Sarath W. Kotagama, Jessie L. Knowlton, Tien Ming Lee, Charles A. Munn, Somchai Nimnuan, B. Z. Nizam, Guillaume Péron, V. V. Robin, Amanda D. Rodewald, Paul G. Rodewald, Robert L. Thomson, Pranav Trivedi, Steven L. Van Wilgenburg, Kartik Shanker
Biology Faculty Publications
Competition theory predicts that local communities should consist of species that are more dissimilar than expected by chance. We find a strikingly different pattern in a multicontinent data set (55 presence-absence matrices from 24 locations) on the composition of mixed-species bird flocks, which are important sub-units of local bird communities the world over. By using null models and randomization tests followed by meta-analysis, we find the association strengths of species in flocks to be strongly related to similarity in body size and foraging behavior and higher for congeneric compared with noncongeneric species pairs. Given the local spatial scales of our …
Effects Of Vegetation, Corridor Width And Regional Land Use On Early Successional Birds On Powerline Corridors, Robert A. Askins, Corrine M. Folsom-O'Keefe, Margaret C. Hardy
Effects Of Vegetation, Corridor Width And Regional Land Use On Early Successional Birds On Powerline Corridors, Robert A. Askins, Corrine M. Folsom-O'Keefe, Margaret C. Hardy
Biology Faculty Publications
Powerline rights-of-way (ROWs) often provide habitat for early successional bird species that have suffered long-term population declines in eastern North America. To determine how the abundance of shrubland birds varies with habitat within ROW corridors and with land use patterns surrounding corridors, we ran Poisson regression models on data from 93 plots on ROWs and compared regression coefficients. We also determined nest success rates on a 1-km stretch of ROW. Seven species of shrubland birds were common in powerline corridors. However, the nest success rates for prairie warbler (Dendroica discolor) and field sparrow (Spizella pusilla) were
The Future Of Blue-Winged And Golden-Winged Warblers In Connecticut, Robert A. Askins
The Future Of Blue-Winged And Golden-Winged Warblers In Connecticut, Robert A. Askins
Biology Faculty Publications
No abstract provided.
Do The Size And Landscape Context Of Forest Openings Influence The Abundance And Breeding Success Of Shrubland Songbirds In Southern New England?, Robert A. Askins, Benjamin Zuckerberg, Leah Novak
Do The Size And Landscape Context Of Forest Openings Influence The Abundance And Breeding Success Of Shrubland Songbirds In Southern New England?, Robert A. Askins, Benjamin Zuckerberg, Leah Novak
Biology Faculty Publications
Early successional birds have declined in the northeastern United States due to the regeneration of forest on abandoned farm fields and the suppression of natural disturbances that once provided appropriate habitat. These species have become increasingly dependent on early successional habitats generated by such activities as timber harvesting. Recent approaches of timber harvesting, which range from single-tree harvesting to clearcutting, create forest openings of different sizes and configurations embedded in landscapes with different land use patterns. To assess the importance of forest openings created by timber harvesting for shrubland birds, we surveyed birds on 50m radius plots in 34 harvest …
Conservation Of Grassland Birds In North America: Understanding Ecological Processes In Different Regions, Robert A. Askins, Felipe Chávez-Ramírez, Brenda C. Dale, Carola A. Haas, James R. Herkert, Fritz L. Knopf, Peter D. Vickery
Conservation Of Grassland Birds In North America: Understanding Ecological Processes In Different Regions, Robert A. Askins, Felipe Chávez-Ramírez, Brenda C. Dale, Carola A. Haas, James R. Herkert, Fritz L. Knopf, Peter D. Vickery
Biology Faculty Publications
Many species of birds that depend on grassland or savanna habitats have shown substantial overall population declines in North America. To understand the causes of these declines, we examined the habitat requirements of birds in six types of grassland in different regions of the continent. Open habitats were originally maintained by ecological drivers (continual and pervasive ecological processes) such as drought, grazing, and fire in tallgrass prairie, mixed-grass prairie, shortgrass prairie, desert grassland, and longleaf pine savanna. By contrast, grasslands were created by occasional disturbances (e.g., fires or beaver [Castor canadensis] activity) in much of northeastern North America. The relative …
Judicious Use Of Multiple Hypothesis Tests, Paul J. Roback, Robert A. Askins
Judicious Use Of Multiple Hypothesis Tests, Paul J. Roback, Robert A. Askins
Biology Faculty Publications
When analyzing a table of statistical results, one must first decide whether adjustment of significance levels is appropriate. If the main goal is hypothesis generation or initial screening for potential conservation problems, then it may be appropriate to use the standard comparisonwise significance level to avoid Type 2 errors (not detecting real differences or trends). If, however, the main goal is rigorous testing of a hypothesis, then an adjustment for multiple tests is needed. To control the familywise Type 1 error rate (the probability of rejecting at least one true null hypothesis), sequential modifications of the standard Bonferroni Method, such …
Relationship Between Habitat Area And The Distribution Of Tidal Marsh Birds, Lori K. Benoit, Robert A. Askins
Relationship Between Habitat Area And The Distribution Of Tidal Marsh Birds, Lori K. Benoit, Robert A. Askins
Biology Faculty Publications
To assess the relationship between marsh area and relative abundance of tidal marsh bird species, we surveyed birds on 86 circular plots in 40 salt and brackish tidal marshes in Connecticut. We measured marsh area in two ways: the amount of contiguous marsh vegetation not interrupted by broad barriers (>500 m of open water or >50 m of upland habitat) and by narrow barriers (>30 m of open water or >10 m upland). We determined the relationship between marsh area and the relative abundance of particular species (mean number of individuals per survey plot) with linear or logistic …
Helping Shrubland Birds, Robert A. Askins
Helping Shrubland Birds, Robert A. Askins
Biology Faculty Publications
Dr. Askins argues that shrublands were part of the pre-Colonial landscape in Connecticut, so it's logical to create forest openings to help shrubland birds.
Sustaining Biological Diversity In Early Successional Communities: The Challenge Of Managing Unpopular Habitats, Robert A. Askins
Sustaining Biological Diversity In Early Successional Communities: The Challenge Of Managing Unpopular Habitats, Robert A. Askins
Biology Faculty Publications
No abstract provided.
Differences In Bird Communities On The Forest Edge And In The Forest Interior: Are There Forest-Interior Specialists In Japan?, Reiko Kurosawa, Robert A. Askins
Differences In Bird Communities On The Forest Edge And In The Forest Interior: Are There Forest-Interior Specialists In Japan?, Reiko Kurosawa, Robert A. Askins
Biology Faculty Publications
Most North American bird species that are less successful in small forests than in large forests, are forest-interior specialists that winter in the tropics. These species have declined in small forests because of high rates of nest predation and brood parasitism near the forest edge. To determine whether migratory forest-interior specialists are also important components of bird communities in Japan, we surveyed bird populations on plots at the edge and in the interior of deciduous forests in Hokkaido and Kyoto. Surveys were conducted during the breeding season in forest fragments using the point count method. We calculated edge indices for …
History Of Grassland Birds In Eastern North America, Robert A. Askins
History Of Grassland Birds In Eastern North America, Robert A. Askins
Biology Faculty Publications
Until recently the severe decline in the populations of many species of grassland birds in eastern North America has aroused relatively little concern or conservation action. This response appears to be rooted in the perception that grassland birds invaded the East Coast from western grasslands after European settlers cleared the forest. Detailed historical accounts and analysis of pollen deposits, however, show that open grasslands existed on the East Coast of North America at the time of European settlement. Extensive grasslands resulted from burning and agricultural clearing by Native Americans. Natural disturbances, such as wildfire and beaver (Castor canadensis) activity, produced …
Reproductive Success Of Ospreys At Two Sites In Connecticut, Donna Christine O'Neill, Robert A. Askins
Reproductive Success Of Ospreys At Two Sites In Connecticut, Donna Christine O'Neill, Robert A. Askins
Biology Faculty Publications
Nest success rates and rates of fish delivery to nests were determined for two large Osprey populations in COlmecticut, one at Groton Reservoir, Groton, and one at Great Island, Old Lyme, during 1996 and 1997. Between 1993 and 1996 these Osprey populations had substantially different rates of nest success. Great Island Ospreys fledged few young while Groton Reservoir Ospreys had good nest success. During 1997, however, fledging rates were similar at the two sites. In 1996, low nest success at Great Island 'resuited from high predation rates, probably due to raccoons. The higher nest success rate at this site in …
Conservation Of Grassland Birds In The Northeast, Robert A. Askins
Conservation Of Grassland Birds In The Northeast, Robert A. Askins
Biology Faculty Publications
No abstract provided.
Open Corridors In A Heavily Forested Landscape: Impact On Shrubland And Forest-Interior Birds, Robert A. Askins
Open Corridors In A Heavily Forested Landscape: Impact On Shrubland And Forest-Interior Birds, Robert A. Askins
Biology Faculty Publications
In eastern North America, remnant patches of forest surrounded by open habitat constitute unfavorable habitat for many species of migratory forest birds because of high rates of nest predation and cowbird parasitism. Although most evidence for this relationship comes from 'forest islands' surrounded by residential or agricultural land, even forest patches isolated from other forests by narrow open corridors such as roads and powerline rights-of-way seem to show this pattern. Productive habitat for migratory birds can be maintained by consolidating corridors and routing them along the periphery of forests to retain as much continuous forest as possible. Consolidation of open …
Population Studies Of Migratory Birds In Virgin Islands National Park, Robert A. Askins, David N. Ewert
Population Studies Of Migratory Birds In Virgin Islands National Park, Robert A. Askins, David N. Ewert
Biology Faculty Publications
The majority of the individual songbirds nesting in the deciduous forests of eastern North America migrate to the West Indies, Central America and South America during the winter. They typically spend more than six months in tropical winter habitats. Until recently relatively little was known about their habitat requirements during the winter, but increasing concern about declining pcpulations of many migratory songbirds combined with widespread alarm about the rapid destruction of tropical forests has led to a flurry of research on this subject (Terborgh, 1989; Askins et al. 1990). In 1987 we initiated a study of the ecology and behavior …
Forest Fragmentation And The Decline Of Migratory Songbirds, Robert A. Askins
Forest Fragmentation And The Decline Of Migratory Songbirds, Robert A. Askins
Biology Faculty Publications
No abstract provided.
Flocking Behavior Of Migratory Warblers In Winter In The Virgin Islands, David N. Ewert, Robert A. Askins
Flocking Behavior Of Migratory Warblers In Winter In The Virgin Islands, David N. Ewert, Robert A. Askins
Biology Faculty Publications
We assessed the flocking behavior of birds on St. John and St. Thomas, U.S. Virgin Islands, with systematic surveys along trails in moist forests. Winter residents (species breeding in North America and that winter in the Virgin Islands), all of which were warblers, comprised 91% of the individuals found in 28 flocks but only 49% of solitary individuals. The average flock size was 4.0 individuals of 3.1 species, and did not differ between St. John and St. Thomas even though the average forest tract on St. John (1,000 ha) was much larger than on St. Thomas (62 ha). Northern Parula …
Protecting Forests For Wildlife, Robert A. Askins
Protecting Forests For Wildlife, Robert A. Askins
Biology Faculty Publications
The subject of managing forests for wildlife is being viewed from a new perspective, a perspective that has developed primarily as a result of studies of forest-interior birds. Forest-interior birds are dependent to a large extent on how forest lands are managed. They are essentially forest specialists and are not normally seen in open areas such as the suburbs, open fields or meadows. In Connecticut and other parts of the northeastern United States, most forest-interior birds are members of one taxonomic group, the wood warblers.
Effect Of Changes In Regional Forest Abundance On The Decline And Recovery Of A Forest Bird Community, Robert A. Askins, Margarett J. Philbrick
Effect Of Changes In Regional Forest Abundance On The Decline And Recovery Of A Forest Bird Community, Robert A. Askins, Margarett J. Philbrick
Biology Faculty Publications
Bird populations were monitored for 32 years in a 23-ha tract of hemlock-hardwood forest. Between 1953 and 1976 the total abundance of long-distance migrants declined significantly and four species disappeared, but after 1976 both the total abundance and the number of species increased. Multiple regression analysis shows that the abundance of long-distance migrants was negatively related to abundance of bird species characteristic of suburban habitats and positively related to the amount of forest within 2 km of the study area. The decline in long-distance migrants before 1976 occurred when suburban species were increasing and nearby forest was destroyed. The increase …
The Effects Of Mute Swans On Native Waterfowl, Maria O'Brien, Robert A. Askins
The Effects Of Mute Swans On Native Waterfowl, Maria O'Brien, Robert A. Askins
Biology Faculty Publications
No abstract provided.
Foraging Ecology Of Temperate-Zone And Tropical Woodpeckers, Robert A. Askins
Foraging Ecology Of Temperate-Zone And Tropical Woodpeckers, Robert A. Askins
Biology Faculty Publications
The foraging behavior of 11 species of woodpeckers in Guatemala, Maryland, and Minnesota was studied in order to test the seasonal stability hypothesis. This hypothesis predicts that specialization and species richness should be no greater for tropical wood-excavators than for those in the temperate zone because wood-excavators in both regions are buffered against seasonal change. Niche breadth values for six variables that describe foraging methods and perches were calculated by two methods. Unweighted niche breadth values were similar for tropical and temperate woodpeckers for all variables except foraging techniques; in this case the temperate species are more specialized. With weighted …