The eastern whip-poor-will (Antrostomus vociferus: hereafter whip-poor-will) has been declining from historical population levels throughout its range in the northeast. Although whip-poor-wills have been reported to use a variety of habitats, most recent studies have associated whip-poor-wills with open habitat, such as early-successional habitats or forest edges. Population declines of other early-successional bird species have been attributed to the loss of early-successional disturbance-dependent habitats in the northeast, and it has been suggested that habitat loss is a significant factor in whip-poor-will population declines, as well. However, there remain substantial gaps in our understanding of whip-poor-will habitat associations, and quantitative habitat data in the literature are lacking. As forest management plays an important role in creating and maintaining habitat for many disturbance-dependent bird species, further characterization of whip-poor-will habitat preferences is necessary to determine whether management efforts may benefit this species as well. In order to derive quantitative estimates of habitat requirements, I studied whip-poor-will habitat associations at Fort Drum in upstate New York. In 2015 and 2016, whip-poor-wills were surveyed at night at randomly-selected point count locations and vegetation measurements were collected in the point count radii to relate whip-poor-will occupancy with structural and compositional habitat variables. Whip-poor-will occupancy was strongly related to intermediate amounts of basal area, with values that generally correspond to forest denser than most shrublands, but more open than closed-canopy forest. Occupancy was also related to lower understory height values, which supports evidence that whip-poor-wills may prefer habitat with a relatively open understory. In 2016, I also measured habitat at locations where whip-poor-wills were foraging, roosting, and nesting, to investigate the theory that whip-poor-wills require open habitat for foraging, but more closed habitat for nesting. Ten adult whip-poor-wills were tracked using radio telemetry and vegetation measurements were collected at a subset at these points where the birds were either foraging or roosting during the day, as well as at any identified nest sites. Comparisons of the vegetation measurements revealed that foraging habitat was significantly more open than roosting habitat, as foraging habitat had lower tree density, basal area, and understory height. Contrary to conventional thought, the few nest sites found in this study were in areas that had low basal area, similar to the habitat at foraging locations. The results suggest that while creating more open-canopy habitat may benefit whip-poor-wills by providing suitable foraging habitat, and potentially nesting habitat, maintaining denser forest within proximity to these open areas may also provide valuable cover for roosting whip-poor-wills. In conclusion, I suggest that land owners looking to create or maintain suitable habitat for whip-poor-wills apply forest management treatments that create openings but still maintain intermediate levels of basal area, such as shelterwood or group tree selection. Foraging habitat for whip-poor-wills appears to be generally more open than roosting habitat, both in terms of lower basal area and a more open understory, so having areas where tree and understory removal is concentrated in proximity to areas that are denser may also benefit this species.

No description available.

Tropical habitats face a diverse range of anthropogenic threats. Two common and important threats to tropical biodiversity are invasive species and roads. Invasive plants are proposed to be a major threat to biodiversity worldwide, yet not much is known about their impacts on higher trophic levels, such as insects. Roads and other linear intrusions, such as power lines and railway tracks, are another common aspect of human disturbance in natural landscapes, including tropical forests, and are often linked to the spread of invasive plants. I studied impacts of these two important proximate drivers of habitat disturbance, namely invasive plant species and roads, on habitat use by butterflies in a tropical moist deciduous forest in Western Ghats of India. Invasive plants and roads are expected to modify micro-habitat structure, resources and other aspects of ecology of butterflies and thereby influence how they use space (i.e., micro-habitats within the larger habitat). Because systematic ecological information on tropical butterflies is comparatively limited, I adopted a multi-species approach. I examined space use responses of butterflies to a gradient of lantana cover in the forest and to a road passing through forest. The abundance of different species of butterflies in different micro-habitats was taken as a measure of habitat use. Data was collected over two seasons and at two spatial scales. The two habitat disturbances were found to influence local habitat use by butterflies. But interestingly, species appeared to respond differently, with some showing positive, others negative and some no clear association with road verge or lantana gradient. I then examined whether this variation in response could be understood in terms of species-specific functional traits. Correlating the responses of species to a habitat disturbance with functional traits may provide a way of arriving at general patterns and increase the ability of studies to predict responses. Species with similar trait values are expected to respond similarly to a habitat change driver. I measured morphological traits in 254 butterfly species from India and classified them according to their habitat preferences (based on expert opinion). I first examined relationships between morphological traits, habitat preferences and evolutionary relatedness. I then examined patterns of correlation between these traits and responses to the two habitat disturbances and found that certain traits can help predict responses. Overall, my study suggests that butterfly space use is influenced by roads and lantana, but the response varies across species. These changes in habitat use might have important population or community-level consequences, such as population declines and shifts in community structure and composition; these need to be further examined.

In recent decades, New England agriculture has become increasingly characterized by small, diversified farming operations with values deeply rooted in community and conservation. In sharp contrast to large-scale, high-intensity agriculture currently typified by the majority of North American farms, New England farmers commonly prioritize ecologically beneficial production practices such as reduced chemical inputs, integrated pest management (IPM), low tillage, cover cropping and crop rotation, and retention of natural habitats like woody hedgerows and herbaceous strips. Public support and demand for local, sustainable food, evidenced by the success of CSA (Community Supported Agriculture) in the region, has helped to bolster this movement and increase the viability of these farms. In addition to boosting regional food production and self-sufficiency, these farms also present an opportunity for wildlife conservation. Shrubland bird species in particular may benefit from habitat created on these farms because of their preference for heterogeneous shrub and herbaceous vegetation and lower area sensitivity compared to other species, such as grassland obligates. In order to evaluate conservation potential and habitat associations of shrubland birds and other priority species on small, diversified farms, we conducted point counts and vegetation surveys across 23 farms in the Pioneer Valley, MA during the summers of 2017 and 2018. We used Poisson-binomial mixture models and canonical correspondence analysis (CCA) to assess the effects of a suite of microhabitat-, field-, and landscape-scale variables on the abundance of bird species. Our results confirmed that shrubland birds, including song sparrow (Melospiza melodia), gray catbird (Dumatella carolinensis), common yellowthroat (Geothlypis trichas) and American goldfinch (Spinus tristis), were the predominant species present, accounting for over 52% of the total observations. Species-habitat relationships were diverse; however, smaller field sizes, and increased cover of tall, dense, woody or nonproductive vegetation types were associated with higher abundance of shrubland species as well as lower abundance of crop pests such as European starling (Sturnus vulgaris) and house sparrow (Passer domesticus). These findings support the hypothesis that small, diversified farms are providing beneficial habitat for shrubland birds, as well as providing species-specific guidelines for farmers interested in conserving birds on their land. In order to place small, diversified farms into a regional conservation context and evaluate their contribution to shrubland bird conservation efforts in New England, we compared bird abundance, community composition, and conservation value of small, diversified farms to five established shrubland habitat types in the region: wildlife openings, two types of silvicultural openings (larger clearcuts and small forest openings created by group selection harvest), beaver meadows, and powerline rights-of-way. We compiled avian survey data from previous studies of each of the aforementioned habitat types conducted from 2002-2006 (powerline rights-of-way, wildlife openings, clearcuts, and beaver meadows) and 2014 (small forest openings). We then compared the relative bird abundance, community composition, and conservation value across all five habitat types (including farms) using Generalized Linear Models (GLMs), non-metric multidimensional scaling (NMDS) ordination, permutational multivariate analysis of variance (PERMANOVA), and calculated an Avian Conservation Significance (ACS) score for each habitat. The avian community composition of farms most closely resembled that of wildlife openings and harbored more open-habitat and generalist species such as American robin (Turdus migratorius), red-winged blackbird (Agelaius phoeniceus), and eastern kingbird (Tyrannus tyrannus). Several shrubland species were found to have higher relative abundances on farms than any of the other four habitats including song sparrow (Melospiza melodia), northern cardinal (Cardinalis cardinalis), and willow flycatcher (Empidonax traillii). Farms possessed a higher ACS score than powerline rights-of-way, small forest openings, and beaver meadows, but were lower than clearcuts and wildlife openings. Our results suggest that small, diversified farms support a unique suite of shrubland species, and while they certainly cannot replace managed shrubland habitats such as wildlife openings and clearcuts, they may complement these existing habitats in terms of their community composition and conservation value.

Because of the scarcity of information for bird communities at the major mainland rivers of southeastern Alaska, the main objective of this study was to provide baseline information including distribution, status, and habitat associations of breeding birds. I conducted a meta-analysis of all known reports (including the current study) conducted at major mainland rivers during the breeding season. I described bird species composition, distribution, abundance estimates, status, habitat associations, and guild membership for all birds recorded at 11 major mainland rivers. Based on incidental observations, 170 species were recorded by all studies. Of these, 134 species were known or suspected to breed, accounting for 50% of all birds known from Alaska and 80% of all birds known from southeastern Alaska. In addition, I provided information on species of management concern as well as management implications and recommendations. I used point counts to survey birds within deciduous riparian vegetation at 6 major mainland rivers during 2000-2002. I compared bird species composition, abundance, richness, and diversity among four main vegetation types of deciduous riparian vegetation: shrubland, young deciduous forest, mature deciduous forest, and mixed deciduous-coniferous forest. Species richness was similar among all habitat types; however, relative abundance and diversity of birds was highest in mixed forest stands. Mature forests had the greatest number of species associated with the Canadian interior. I also used point counts to compare bird species composition, abundance, richness, and diversity among 6 major mainland rivers consisting of three trans-mountain and three coastal rivers. Latitude, connectivity, and availability of mature and mixed forests were the major factors thought to cause differences in bird communities among rivers. Contrary to our predictions, coastal rivers had higher bird species richness, diversity, point abundance , and point richness than trans-mountain rivers. Of the 10 species associated with the Canadian interior recorded during point counts, 8 occurred at both trans-mountain and coastal rivers.

The nearshore waters off the Oregon coast (< 73 meters) are a region of high productivity and economic value, with a variety of habitats that include rock outcrops. Temperate reef habitats are important to many commercially important fishes inhabiting the Pacific coast, including canary rockfish (Sebastes pinniger) and yelloweye rockfish (Sebastes ruberrimus), which are currently listed as "overfished" by the Pacific Fishery Management Council. Along the Pacific coast of North America, nearshore rocky reefs have been designated as essential fish habitat (EFH), while comprising approximately just seven percent of Oregon's territorial sea. Despite this EFH designation, the use of visual (SCUBA, remotely operated vehicles (ROVs), human occupied vehicles (HOVs)) and non-visual (bottom trawl) survey methods within this region has been infrequent and scattered, providing limited information on species-habitat associations and species assemblages within nearshore waters. It is logistically difficult and costly to survey nearshore reefs. The factors that have led to the paucity of surveys include the depth (too deep for SCUBA surveys but too shallow for larger survey vessels), high seas limiting available days for field work, and the high-relief nature of the habitat (precluding the use of bottom trawls). In an effort to better understand species-habitat associations and community structure of Oregon's nearshore reefs, an autonomous underwater drop-camera termed the "video lander" was employed at the Three Arch Rocks reef, a nearshore reef off of Oceanside, Oregon. Video lander footage was used to identify and groundtruth habitat types, as well as species assemblages over two distinct seasons: spring/summer (n=272) and winter (n=108). Many species-habitat associations were statistically significant: yelloweye rockfish (large boulder p<0.0073), canary rockfish (small boulder p<0.0006), kelp greenling (Hexagrammos decagrammus) (bedrock outcrop p<0.0162), and quillback rockfish (Sebastes maliger) (large boulder p<0.0016). Summer and winter surveys revealed similar habitat associations and distributions for these species. I found no significant difference in species composition between the northern and southern regions of the reef (Bray-Curtis dissimilarity index (BCDI) = 71.71, ANOSIM p>0.1447), but a significant difference between spring/summer and winter seasons was identified on the outer section of the reef, due to the presence of spotted ratfish (Hydrolagus colliei) in the winter (BCDI =76.41, ANOSIM p < 0.0155). My study shows that data provided by the video lander can fill existing gaps in our understanding of nearshore distribution and habitat associations of temperate rocky-reef fishes off the Oregon coast. / Graduation date: 2013

Water availability affects tree species performance and distributions in tropical forests. However, there are no studies that have measured detailed spatial variation in soil water availability within a tropical forest. This limits our understanding of how water availability shapes the demography and distributions of tree species within tropical forests. In this dissertation, I measured detailed spatial variation in soil water potential (SWP), the relevant measure of water availability for plant performance, in the seasonal tropical moist forest of the 50-ha Forest Dynamics Plot on Barro Colorado Island, Panama. In Paper 1, I mapped spatial variation in SWP across the 50-ha plot in various stages of the dry season using information on topography, soil type, dry season intensity and more. In Paper 2, I quantified the soil moisture niches of species in terms of demographic responses (growth and mortality) and species distributions. I related seedling growth and mortality responses to SWP of 62 species to their distributional centre along the SWP gradient, using data from 20 years of annual seedling censuses across 200 seedling census sites. I found that species that grew faster (slow) with increasing SWP were more common on wetter (drier) parts of the SWP gradient. Moreover, wet-distributed species grew faster on the wet side of the SWP gradient than dry-distributed species. Mortality was unrelated to species distributions but decreased strongly with seedling height. These findings indicate that species with a growth advantage with respect to SWP grow faster out of the vulnerable small size ranges, reducing their mortality in later seedling stages and thus shaping species distributions indirectly. This mechanism is a form of niche differentiation that contributes to species coexistence. In Paper 3, I related seedling growth and mortality responses to spatiotemporal variation in water availability with responses to light availability, another highly limiting resource in tropical forests. I found an interspecific trade-off in responses to shade versus inter-annual drought (dry season intensity): species that performed relatively well in the shade performed worse during more severe dry seasons and vice versa. This trade-off enables coexistence, because species are adapted to perform well under either shade or drought. In sum, water availability contributes to the maintenance of the high diversity of tropical forests through hydrological niche differentiation and a trade-off between performance in shade versus drought. Future work can use my SWP maps and species responses to SWP to identify the functional traits that underlie the species responses and improve Dynamic Global Vegetation Models. Finally, my work facilitates the prediction of future species composition, diversity and ecosystem functioning of tropical forests with shifts in rainfall patterns caused by climate change.