Thursday, March 19, 2015

Migratory Patterns of Bats in PA

Migratory tree bats are long-distance latitudinal migrants; remain active as long as prey is available. Migratory tree bats are especially difficult to study. Hibernating cave bats live in colonies but tree bats make long-distance migrations. Tree bats are difficult to study because they are solitary. The challenge to MTB is finding what they do when not migrating. Linear landscape features attract MTB.

Important to study them because wind turbines are a serious conservation threat for MTB--100,000 dies each year from just one tree farm area. Locust Ridge Wind Farm 75 percent fatality. Behaior during migration makes them susceptible.

Used acoustic monitoring to echolocate bats. SonoBat is program to identify the echoes. Activity Late June to late August for red bat. Roost surveys found evidence of southward migration in eastern bats different in Iowa. Peak fatality coincides with southward migration.

Hoary Bat's activity occurred at the river mid-April to late May and again in mid July. Northward migration late April to early May and southward mid-July to mid-September. Delaware River may serve as a migratory opportunity for these bats.

Silver-haired Bat: ridge and river activity mid-April to late-May and at the ridge from mid-August to early October. Northward migration late April to late June and southward late August to late October. This bat may be using both ridge and river as well as different landscape features.


Seasonal activity patterns documented provide evidence of migration. It coincides with the timing of migration documented in other studies. Evidence that the Hoary and Silver-haired bat migrate along linear landscape features. Evidence of southward migration coincides with the timing of peak fatality at a local wind farm. Migratory tree bats are the most susceptible to fatality in migration.

1. How can you encourage bats to populate your location? Bat houses: structure and location are important.

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