Hi Tweets,

gary nichols writes:

(snip)
>In the two bird guides I have purchased, the size listing for the
>various birds is listed as 8",10", etc. Does this refer to the wingspan or
>head to tail length.

Simple question, kind of complicated answer.

Normally, length is measured from bill-tip to tail-tip. You need to remember
that measurements in field guides are usually a ballpark figure, as length
of a given individual bird can change according to a number of factors. As a
few examples:

--younger birds often have shorter bills than adults, such as some
shorebirds; the difference between a juvenile male Long-billed Curlew
Numenius americanus and a typical adult female is enormous--much more useful
would be base-of-bill to tail-tip in this instance;
--pre-molt birds with abraded tail-tips;
--females and males differing in their 'average' sizes; ie, raptors where
some species' females can be a full third bigger than the males, or some
shorebirds such as Ruff Philomachus pugnax or Pectoral Sandpiper Calidris
melanotos where males are drastically larger;
--differing sizes of birds belonging to different subspecies within the same
species; the difference in size between the smallest race of Canada Goose
Branta canadensis (minima) and the largest (maxima) is almost the same
between a medium-sized puddle-duck and a small swan;
--the genetic and general health of the individual.

Another factor, over which the bird naturally has little control, is
shrinkage from the dessication of the soft-tissue parts of the carcass when
lies for some time in a collection tray. Ornithologists and their often
unsung assistants, and both professional and amateur banders usually take
measurements at the time they capture and/or kill the bird.

For most passerine species, the differences are piddlin', and of interest
mainly to those pursuing some types of research, but in other families, the
differences may be part of the identification process even at the
introductory level.

But, hey, if anyone asks, just tell 'em it was smaller than a breadbox. '-)

Michael Price
Vancouver BC Canada
mprice at mindlink.net