Date: Wed, 8 Aug 2001 22:08:10 -0400
Reply-To: Eran Tomer <etomer@EMORY.EDU>
Sender: Georgia Birders Online <GABO-L@LISTSERV.UGA.EDU>
From: Eran Tomer <etomer@EMORY.EDU>
Subject: Re: Information to help with young bird identifications
Content-Type: TEXT/PLAIN; charset=US-ASCII
Uneven development of nestlings is very common, perhaps even the norm for
most birds. Several factors contribute to this phenomenon, e.g. some
chicks usurp much more food than others.
The following book probably comes the closest to what you are looking for.
It contains a great deal of breeding-related information not present
The birder's handbook: a field guide to the natural history of North
American birds including all species that regularly breed north of
Mexico. Paul R. Ehrlich, David S. Dobkin, Darryl Wheye; illustrated by
Shahid Naeem. New York, Simon & Schuster, 1988.
Some information also in:
Lives of North American birds / Kenn Kaufman. Boston, Houghton Mifflin
These books, however, don't contain detailed information on birds' life
histories (e.g. what percentage of fledgelings survive their first year).
Such figures vary tremendously even within one species, depending on a
whole range of factors. This type of info. is found mostly in technical
ornithological publications and frequently applies only to one species in
one setting. Even comprehensive reviews typically quote a few local
It should be noted that, while this type of information is very important,
there are enormous gaps in our knowledge. These gaps in basic natural
history make it difficult to assess the true status of many birds, produce
various population projections, make management decisions and take
conservation action. America has a fairly recent research program called
MAPS (Mapping Avian Productivity and Survivorship) that gathers life
history data. It is already producing excellent results, as are programs
in Europe and elsewhere.
There is absolutely no replacement for sound knowledge of natural history.
If you are aware of any nesting birds, save perhaps our commonest species,
it would be very worthwhile to make detailed observations on the process
and publish them in the Oriole. Of course, it should be stressed and
doubly-stressed that studying nesting birds requires extreme care.
- Eran Tomer