Bat activity patterns relative to temporal and weather effects in a temperate coastal environment

(Uploaded by Plazi for the Bat Literature Project) The northeastern and mid-Atlantic coasts of the United States are important summer maternity habitat and seasonal migratory corridors for many species of bats. Additionally, the effects of weather on bat activity are relatively unknown beyond coarse nightly scales. Using acoustic detectors, we assessed nightly and hourly activity patterns for eight species of bats over 21 consecutive months at Fire Island National Seashore, New York. The site is an important bat conservation area because it hosts one of the few confirmed northern long-eared bat (Myotis septentrionalis) maternity colonies in the region despite their widespread extirpation due to whitenose syndrome (WNS). There have been no reported captures of little brown bats (M. lucifugus), Indiana bats (M. sodalis), or tri-colored bats (Perimyotis subflavus) at the site post-WNS. Overall, we found mean hourly temperature, time since sunset, day of year, and year to be the most important predictors of bat activity levels for all examined species. Most non-hibernating, migratory species in our study demonstrated a positive relationship to mean temperature at the hourly timescale, whereas cave-hibernating bats tended to show a negative relationship to mean temperature during the time of year when they are expected to be active. Although most bat activity occurred in the late spring through early autumn, peaking in summer, some activity occurred periodically in the winter months, mostly attributable to the big brown bat (Eptesicus fuscus) and silver-haired bat (Lasionycteris noctivigans) phonic group. Unexpectedly, relationships of bat activity to wind and precipitation were largely equivocal. Initial presence (as early as March 30) and departure (between November 1–4) for northern long-eared bats at our study area occurred earlier in the spring and later in the fall than occurs for inland populations, suggesting that the species overwinters on Long Island rather than at inland karst caves or mines. A peak in spring activity characteristic of migratory behavior in the central Appalachians and Atlantic Coast was not observed at Fire Island, although Eastern red bats (Lasiurus borealis) and hoary bats (L.