Please bring your lab notebook, a pencil or pen, good walking shoes and appropriate clothing. Binoculars are available, if you want them. I will provide field guides to the birds, mist nets and poles, U.S. Fish and Wildlife bands, calipers for measurement, electronic balance or spring scales for determining weight, banding forms, and other materials necessary for bird-banding.
Mist-nets had been used to capture birds in Italy and Japan for many years before
the technique was discovered by ornithologists interested in avian migration.
Nets consist of delicate dark nylon or monofilament webbing stretched between
a frame of stouter horizontal and vertical cords. Nets are set in promising
flight paths of birds, near fruiting plants, around nests, or anywhere where
birds are likely to fly by. A bird is trapped after it hits the webbing and
becomes entangled in the pocket formed by a cross-support cord.
In addition, we may trap individual birds using a specially designed feeder.
The feeder has a remote-control door that allows us to selectively capture individuals
as they approach bird seed.
Individually numbered aluminum bands serve to mark birds permanently and harmlessly.
Bands are issued by the U.S. Fish and Wildlife Service to licensed banders only.
In addition, avian ecologists sometimes place plastic color bands on birds’
legs in unique combinations to allow the birds to be recognized at a distance.
Some recent studies suggest the possibility that color bands can change birds’
behavior (e.g., females might prefer males with bands of a certain color). How
can a field ecologist avoid or at least minimize such potential biases?
Feeders have been placed at the BFEC and near the aviary. With the advent of
cool weather, birds come readily to feeders. We hope to be able to capture enough
for everyone to see how to extricate them from nets, and handle, band, and measure
them safely.
To remove a bird from a mist net, it is important to determine from which direction
the bird entered. Work from that side, following the instructions on the next
page. WE ALWAYS HANDLE BIRDS WITH EXTREME CARE! Bird bones are generally hollow
(why?). Consequently, they are extremely fragile. Until you have had extensive
experience, never hold a bird just by its legs, wings, or bill.
Using special pliers, bands can be bent around the unfeathered, distal portion
of a bird's leg (tarsometatarsus). When banding a bird, you should hold the
bird yourself, grasping it firmly and carefully clamping the band around its
leg, making sure afterwards that the band slides easily.
For each bird the following data should be taken: date (including year), time
of day, location, habitat, species, AOU No. (the number assigned to the particular
species by the American Ornithologists’ Union, band number, and, if possible,
age and sex (determined generally by plumage, size, and other features). Morphological
measurements that are often taken are weight (to 0.1 g using a scale), wing
length and width (to 1 mm using a wing ruler), tarsus length, and, if there
is time, bill depth (at the nostril) and length (from the distal end of the
nostril to the bill tip) (to 0.1 mm using dial calipers). Additional measurements
include presence or absence of parasites, status of molt, and the extent of
subcutaneous fat deposits. Fat reserves are scored as follows:
A functional morphology analysis of the data could include relative wing loading (body mass/wing area), an allometric analysis of wing length vs. body mass, bill length vs. depth, etc. The morphology of birds with different social systems (flocking vs. solitary), mating systems (polygamous vs. monogamous), phylogeny, or movements (migratory vs. sedentary) could be compared. Sometimes blood samples are also taken to estimate population genetic structure, relatedness between individuals, hormone levels, etc.