Foraging habitat use of breeding barn swallow (<i>Hirundo rustica</i>) in farmland, estuary, and island

The decline of barn swallow populations may be mainly caused by the reduction of their foraging habitat. A clear understanding of the links between proportions of available and used microhabitats of foraging barn swallows in farmland, estuary, and island habitats would enhance our understanding of the foraging habitat requirements of this species and on the effects of anthropogenic activities, such as habitat conversion (e.g., land to water, crop fields to non-arable land), on their distribution. We hypothesized that: 1) foraging swallows would be more abundant in the most common microhabitat;and 2) swallow abundance would decrease with increased foraging distance from the nest-site. As predicted by our first hypothesis, swallows were more abundant in the most common microhabitat (i.e., crop fields in farmland and non-arable land on the island). Our data also support our second hypothesis that increased foraging distances from the nest-site negatively affected foraging swallow abundance. In summary, barn swallows foraged in the habitats most convenient to nest-sites, however, management of agricultural lands should include non-arable lands in the composition of available foraging microhabitats.

Seasonal comparison of aquatic macroinvertebrate assemblages in a flooded coastal freshwater marsh

Marsh flooding and drying may be important factors affecting aquatic macroinvertebrate density and distribution in coastal freshwater marshes. Limited availability of water as a result of drying in emergent marsh may decrease density, taxonomic diversity, and taxa richness. The principal objectives of this study are to characterize the seasonal aquatic macroinvertebrate assemblage in a freshwater emergent marsh and compare aquatic macroinvertebrate species composition, density, and taxonomic diversity to that of freshwater marsh ponds. We hypothesize that 1) freshwater emergent marsh has lower seasonal density and taxonomic diversity compared to that of freshwater marsh ponds;and 2) freshwater emergent marsh has lower taxa richness than freshwater marsh ponds. Seasonal aquatic macroinvertebrate density in freshwater emergent marsh ranged from 0 organisms/m2 (summer 2009) to 91.1 ± 20.53 organisms/m2 (mean ± SE;spring 2009). Density in spring was higher than in all other seasons. Taxonomic diversity did not differ and there were no unique species in the freshwater emergent marsh. Our data only partially support our first hypothesis as aquatic macroinvertebrate density and taxonomic diversity between freshwater emergent marsh and ponds did not differ in spring, fall, and winter but ponds supported higher macroinvertebrate densities than freshwater emergent marsh during summer. However, our data did not support our second hypothesis as taxa richness between freshwater emergent marsh and ponds did not statistically differ.