individuals, and this sort of trapping bias may seriously compromise the scientific
value of the results obtained. In general, methods in which the bird is unaware of
any risk are preferable to those in which a bird’s fear of novel situations (neophobia)
might come into play.
Whatever method is used, some general guidelines apply. First, remember that
a trapped bird is vulnerable: it may be stressed, unable to escape from predators
and exposed to weather effects such as heat, wind, or rain. Operations must be
planned to reduce this stress, and the associated risks. This means not trapping in
wind, rain, or direct sun unless shelter is provided within the trap, or you can
guarantee the rapid removal (extraction) of captured birds. Even in the tropics,
hypothermia is a more universal risk to birds than hyperthermia, but note that
some deep-forest birds (e.g. Ant-thrushes, Formicaridae) can die of shock if
brought into direct sun. Predators sometimes learn to associate traps with food
and, if you are not alert to this risk, will incorporate your trap sites into their daily
foraging rounds (trap-lining), if allowed to. This is especially a problem in the
tropics where a great range of predators, including ants, snakes, birds including
coucals and raptors, carnivores, primates and megadermatid bats, have been
known to take birds from mist-nets. Alternating sessions between different net
lanes or trap series can reduce this risk.
Once removed from the trap or net, birds must be kept individually (birds of
some species will kill each other if kept together) in bags or larger keeping cages.
These must be kept clean and dry, and placed out of direct sun. Speed of opera-
tion means having enough helpers to cover all procedures adequately so that no
bird is in a net for more than about 20–30 min from capture (10 min if birds are
exposed in nets to tropical sun). In allowing time, remember that there might be
unforeseen problems arising from difficult extractions, unusually large catches,
snakes etc. All people involved must be adequately trained or supervised, and
must know about any local hazards; remember also that the temperament of
some people changes in pressurized situations.
It is advisable to map net and trap sites with a GPS, and adopt some system
(e.g. removable reflective labels) to prevent traps/nets from being lost or forgotten
in a net round; count traps when set out and when collected back. Knowledge of
the area in which you are trapping, and of the species likely to be encountered, is
invaluable if available. For example: (a) hummingbirds are hardy, but need to feed
frequently, so you should have some fresh sugar-water to hand to give them on
arrival at the ringing station or before release (protrusible-tongued birds such as
spider-hunters, Nectariniidae, are usually happy to drink while being held in the
hand). (b) Long-legged waders (shore-birds) can suffer from leg-cramp (capture
myopathy) if kept from standing for any length of time. They must therefore be
88 |Birds in the hand