Page 104 - BBC Wildlife Volume 36 #12

OURWILD WORLD

BIRDS Wilson's storm petrel is
a widespread member
Why are the of the tubenose family
(Procellariiformes). Note
tubenoses so called? the diagnostic yellow
webbing on its feet.
The nostrils of tubenoses, an order of seabirds
Amade up of albatrosses, petrels, shearwaters
and storm petrels are, as their name suggests,
encased in tubes along the sides or top of the bill.
The tissue inside the tubes is intricate and has a
large surface area, giving the birds a stronger sense
of smell than many other species. This heightened
olfactory system is used to forage near the surface
of the sea and also to sniff out land-based nest
burrows. The latter is a particularly useful strategy
for smaller tubenoses, such as thin-billed prions,
which return to their colonies under cover of
darkness to evade predatory skuas.
The tubes also drain excess salt taken in when
the birds drink seawater, which is then excreted
from glands above their eyes. Liz Kalaugher

The Explainer HERPETOLOGY

Extended Why do grass snakes knot themselves up?
phenotype Such is the flexibility of grass (and famous ‘play dead’ response. When
A other) snakes that they can sometimes threatened by predators, these reptiles often
tie themselves in knots as they settle into bunch their coils and stay stock still, lolling
tight grasses or slither into narrow cracks. their tongues and rolling their eyes into
How intentional this behaviour is remains their skulls with theatrical aplomb. The
largely unknown. It certainly doesn’t seem behaviour is reasonably common in adults,
to cause grass snakes any obvious problems. but rarer in young snakes. One study found
They usually simply pull the knot wide with that 66 per cent of wild-caught grass snakes
their super-muscular skeleton and slide exhibited the death-feigning response when
through the loop as if the knot weren’t there. threatened, yet no (lab-reared) hatchlings
Tying itself in a knot can also be an appeared to rely on this adaptive behaviour.
accidental by-product of the grass snake’s Jules Howard

Is a bowerbird's bower
just an extension of
the bird?

The recipe for building an animal
or plant is written in its genes.
But genes influence more than
an organism’s physical form and Petre : Hanne & Jens Eriksen/NPL; bowerbird: Konrad Wothe/FLPA; grass snake: Frank Paul Fietz/Imagebroker/FLPA; mackerel: Alex Mustard/NPL
behaviour (phenotype). They also
impact its environment (think
beaver dams and termite mounds)
and the behaviour of others (eg
willow warbler manipulated by
a cuckoo chick). An extended
phenotype includes any influence
that changes the odds of those
genes being passed on. Ultimately, By playing dead, this grass
the concept redefines an organism snake may dissuade predators
as something more than its – including badgers, foxes,
hedgehogs and domestic
physical body. SB
cats – from tucking in.

104 BBC Wildlife