Page 53 - BBC Wildlife Volume 36 #11

WILDNEWS

SEABIRDS
Cracking the

guillemot’s egg

veryone knows guillemots’ pointy eggs
Eare shaped to roll in an arc to stop them
falling from their cliff-ledge nests. Trouble
is, it’s not true – they roll in too wide an arc.
Last year, Tim Birkhead of the University
of Sheffield found evidence that the shape
is more about hygiene on guano-encrusted
ledges (BBC Wildlife, May 2017).
Now, Birkhead has published what he
believes is a better explanation: “While
doing fieldwork, the idea popped into my
head that the shape of a guillemot egg
would be more stable on a sloping ledge.
Over 50 per cent of guillemot ledges are
sloping. I tried it and it worked.”
Razorbills’ eggs, which are more
classically egg-shaped, were far less secure
on a slope. “More rigorous experiments
confirmed that the more steeply sided the
egg, the more likely it was to stay put.”
The shape might yet turn out to serve
multiple functions: extra strength, as a
defence against the impacts of crash-
landing parents, included. And Birkhead’s
not ruling out the hygiene hypothesis. “It’s FIND OUT MORE
clear that the blunt ends, containing the The Auk: Ornithological
chicks, stay relatively clean.” SB Advances https://doi.
org/10.1642/AUK-18-38.1

NEW SPECIES DISCOVERY IN NUMBERS

Clistopyga 50,000

crassicaudata pairs of tawny owls live in the
UK,down 30 per cent in 25
years.Take part in theTawny Owl
WHAT IS IT? The egg-laying
Calling Survey if you hear one
organs – or ovipositors – of ants,
between now and March 2019.
bees and wasps double up as
stings. Some species put them
to other uses. Close relatives of 47
this newly discovered ichneumon
is the number of years that Moby
wasp use theirs to entangle the silk
– the oldest captive dolphin –
surrounding the exit holes of spiders’ This preserved
nests before stinging the inhabitant and specimen of was held in captivity before dying
Clistopyga shows in Nuremberg Zoo in Germany.
laying an egg on its paralysed body. The
its large stinger.
precise function of the new species’ huge
ovipositor is not yet known. 12.5m
WHERE IS IT? This species, found in Peru,
ducks,geese and swans will be Guillemot: BSIP/Getty; clistopyga: Kari Kaunisto
is one of seven new species of Clistopyga
arriving this autumn to spend the
discovered in a narrow zone of vegetation SOURCE Zootaxa: www.
winter in the UK,according to the
between the Andes mountain chain and mapress.com/j/zt/article/
British Trust for Ornithology.
the Amazonian rainforest. view/zootaxa.4442.1.5

November 2018 BBC Wildlife 53