transferred from nets or bags to keeping cages in which they can stand as quickly
as possible. In many areas, but especially in the tropics, bird activity tends to
peak early in the day and may peak again just before rain (requiring extra care).
Trapping later in the day may be unproductive, but the profitability of netting in
the evening varies, and extra vigilance is necessary if trapping at night.
Apart from direct means of catching birds (e.g. pulli—see below, swan-hooks
and batfowling), a useful distinction to make is between traps, which tend to be
set for individual birds, and nets, which typically catch many birds simultan-
eously. Some traps must be baited with some sort of lure such as food, and nets too
may be more effective if bait is provided nearby. Both traps and nets present risks
to birds if operated by unskilled staff. The seminal work of Bub (1991) on bird
trapping carries 456 text figures, illustrating more than 150 different trapping
methods. Given this, then, it is remarkable that today most birds are trapped for
research using just a handful of methods, described below.
4.3.1The breeding season
The breeding season presents a period of intense enquiry for the researcher, and
intense activity and sensitivity to disturbance for most bird species. Nests, eggs,
chicks, and adults at the nest, are vulnerable to predators. This means that the num-
ber of visits should be minimized, and in general trapping of adults and marking of
young should be left as late as is consistent with preventing the brood leaving the
nest prematurely, and with logistic considerations. For many passerines there is
a risk of desertion if the incubating females are lifted off the nest. However, for some
it is safe to do so, in which case this may offer a valuable means of sampling. Advice
should be sought for particular species before undertaking such a procedure.
Young birds prior to fledging are known collectively as pulli(singular pullus).
For the researcher, there are some obvious advantages to ringing birds as pulli,
since their exact origin and age are known, and it might be possible to trap
the parents also. The disadvantages concern welfare, since pulli are vulnerable
to rough handling, predators and the elements. Nidicolous young (which stay in
the nest after hatch) should not be ringed until flight feathers have emerged by at
least a quarter from the pin; nidifugous young (which leave the nest shortly after
hatching) of many species can be ringed from hatching but always check the fit of
the ring to be sure that it cannot slip down over the foot, and that it will be large
enough to take the full-size leg. Some researchers have tried inserting plasticine
inside the fitted ring, which gets squeezed out as the leg grows. However, there are
several reasons why this might be unsafe (e.g. plasticine might go hard in water)
and the method is not generally recommended. Do not mark nest positions con-
spicuously as crows can learn to associate the marks with food (see Chapter 3).
Catching the birds| 89