Bat House Forum

[Dave Miller]

http://canopy.evergreen.edu/bcd/content ... efid=11600

I don't have access to the actual article, but the summary had a few interesting tidbits which I have highlighted:

Citation:
Randall, L. A., R. M. Barclay, M. L. Reid and T. S. Jung. 2011. Recent infestation of forest stands by spruce beetles does not predict habitat use by little brown bats (Myotis lucifugus) in southwestern Yukon, Canada. Forest Ecology and Management 261:1950-1956.

Reference type: Journal Article

Abstract:
Insect outbreaks affect forest structure which may have significant effects on the habitat of other animals. Forest-dwelling insectivorous bats are likely affected by associated changes in the abundance of roost trees and insect prey, altered foraging and flying efficiency, and predation risk. We examined the short-term effects (3-13 years post-infestation) of an outbreak of spruce beetles (Dendroctonus rufipennis) on the habitat use of little brown bats (Myotis lucifugus) in the boreal forest of the southwestern Yukon, Canada. We measured bat activity, using Anabat II bat detectors, in 90 forested stands that had experienced from 0 to 90% tree mortality due to spruce beetles. We used generalized linear models to assess whether bat activity varied with tree mortality, season, tree density, canopy closure, or distance to the nearest lake or town. Bat activity did not vary significantly with tree mortality, season, or canopy closure, but decreased with increasing tree density. Bat activity was significantly greater in areas close to both the nearest lake and nearest town, and was low in areas that were far from either. Our results indicate that in the short-term, habitat use by little brown bats was not related to the severity of spruce beetle infestation, but suggest that in the long-term, bats may be positively affected by decreased tree density as beetle-killed trees fall down.

So in SW Yukon, little brown bats seem to prefer:
- Low tree density
- Near lake
- Near town

The lake is no surprise but the low tree density & near a town is news to me.

Any theories?

[BrackishBatter]

Perhaps being near towns and low tree density are the same thing? Maybe areas of human activity are more conducive to the presence of favorable insect species? Dunno, interesting though.


ETA: Sometimes I read my own posts and wonder if I'm as smart as I think I are.

What I meant to say is that I suppose high tree density means they have to hunt above the canopy, and they may prefer more room to manuever at lower altitude. If so, then it follows that maybe both conclusions make sense because. . .being near towns and low tree density are the same thing?.

Alternantively, Maybe areas of human activity are more conducive to the presence of favorable insect species?, though that seems a stretch. Or maybe human domociles provide more stable, favorable roosting sites with fewer predators.

Dunno, interesting though.

[Joe Spencer]

Great info Dave and it makes sense. After personally camping at numerous campsites over the years with my family which had a lake and forest which had of course all the campsites and areas leading to them via dirt and paved road width which favored little brown bat and myotis bat foraging, little browns were dense on these pathways as I walked them in the evening. I could hear and feel their wings and air movement as they flew by me constantly while walking with my small flashlight. Since little browns on average forage at lower heights than big browns which forage at upper tree top heights with occasional dips down to forage in open spaces, it seems humans have created favorable feeding habitat for many species of bats. If they had to feed within deep dense forest with no open spaces one would think they would spend more time using echolocation to avoid trees and vegetation than pinpointing prey thus consuming precious fat reserves. Sadly on my walk this year at two sites I/we were bitten constantly by mosquitoes which were worse this year than last year at this site. 10 years ago at this site we didn't even need repellent later in the evening after bats had consumed most of them. WNS is likely the factor as the LBB population was the lowest in my bat houses at one of these campground sites since I erected them years ago and since I've been monitoring the past 15+ years.