Page 109 - BBC Wildlife - August 2017 UK

Q&A

Q BIRDS Q BIRDS
Howw does a bird What is moult migration?
get red-listed?
A
A Thhe‘red list’is one of three categories Moult migration is a form of sites usually lie to the north of the
(with‘green and amber ) used to identifygreen’and‘amber’) used to identify migration seen in some ducks and breeding range, which is why we
the conservation status of birds in the UK, geese. It occurs towards the end of the see introduced Canada geese from
Channel Islands and Isle of Man. Status breeding season and sees individuals southern Britain gathering at sites
is reviewed periodically, with the most travel a substantial distance to gather in Scotland. The moult migrations
recent taking place in 2015. Evidence of a at traditional sites. These sites are undertaken by ducks tend to be more
significant decline in breeding population selected because they offer food and variable in terms of the direction
was the most important criterion, and safety from predators, allowing the flown. British shelducks, for
67 species were red-listed, including the birds to replace their flight feathers – a example, fly east to join thousands
curlew (above) and pue ffin. process that leaves them flightless and of other individuals from elsewhere
Mike Toms potentially vulnerable. in western Europe at moulting sites
In geese, only the non-breeders located on the tidal mudflats of
or those individuals whose breeding Germany’s Wadden Sea. MT
attempts have failed make moult
migrations. The selected moulting

Canada geese,
introduced to the
UK in 1665, are
now widespread.

Q BIOLOGY

Can any animay

mate with two

partners at onc

A In some fish, frogs and other externally fertilis
not unusual for females to be smothered by multi
for the best position to fertilise her eggs. And in s
fertilising species, individuals of either sex may c
than one mate in quick succession. In only one, t
American dotted wolf spider – are females routin
The panda’s diet – the latest by two males simultaneously, something madeposssible bythe It’s double
explanation for its distinctive females having two reproductive openings. Courting a potentiallyill t trouble forbl f
coloration – consists almost cannibalistic female is perilous for the males, which is why some female dotted
entirely of bamboo. The plant’s wolf spiders at
scant nutritional value means suitors adopt the strategy of loitering in the shadows while their mating time.
the animals must eat up to rivals take their chances. Only when the female has been subdued
38kg of the stuff daily. will theobserver nip in to join the party. SB
BBC Wildlife 109