Subject: [Tweeters] nighthawks and insect abundance
Date: Jul 7 11:06:17 2006
From: Alt8bird at aol.com - Alt8bird at aol.com


As a follow-up to nighthawks and insect abundance.....If you look at Breeding
Bird Survey trends for the northwest (and actually continentally) one
grouping of bird species that has a vast majority of the species as declining
(probably the most next to grassland birds) is aerial insectivores (considering
flycatchers, swifts, swallows, and nighthawks). I haven't looked at the latest
trend results, but in the recent past probably 80% of this group of species has
declining trends of which 80% of those are significantly declining trends. It
is alarming and clearly stands out when you look at any other way of grouping
species such as foliage gleaners, bark foragers, ground foragers, cavity
nesters, ground nesters, long-distance migrants, short-distance migrants, etc....

So what about purple martin? It is clearly an exception (maybe the only
one), and of course there are almost always exceptions becasue the natural world
is just not simple and linear, and one could speculate why it is an exception
(I will let you guys do that), but to me the exception should not drive the
bus.....or dismiss or reduce what the vast majority of the data is telling us.
There is likely a connection and probably a strong connection between prey
(i.e. aerial insects) availability and the decline not only of common nighthawk,
but most other aerial insectivores.

Bob Altman
American Bird Conservancy
Northern Pacific Rainforest BCR Coordinator
311 NE Mistletoe
Corvallis, OR 97330
phone/fax - 541 745-5339
baltman at abcbirds.org