Page 104 - BBC Wildlife Volume 36 #11

OURWILD WORLD

Shieldbugs – here a
INVERTEBRATES green shieldbug on
oak – probably smell
Why do shieldbugs better than they taste.

smell of marzipan?

Though they assume a heroic heraldic title in
ABritain, shieldbugs are often called stinkbugs
elsewhere in the world because of their striking
scents. Most British species use camouflage coloration
to hide from predators, but should one be picked up
in the beak of a bird, it will release a series of volatile,
low-molecular-weight compounds from glands under
its thorax. The resulting odour may be reminiscent
of an oily almond, yet the taste is bitter and acrid,
prompting the predator to release its catch.
The chemicals are harmless, but can result in
staining. Handling the woundwort shieldbug at a
wildlife event to demonstrate the smell to children left
my palm coloured brown for days. Richard Jones

EUROPEAN MAMMALS
The Explainer
Are black squirrels a separate species?
r and K selection

Black individuals of both the eastern has a recognisably different morphology. It
Agrey (the invasive rodent now well is larger, with more prominent feet and a
established in Britain) and red squirrels are darker back and tail than the black form of
reasonably common. These are not distinct the red squirrel. It also occurs in a different
species, but melanistic forms. However, a habitat, preferring mature pine forests in
study published earlier this year recognises mountainous areas, and its mitochondrial
the Calabrian black squirrel, endemic to DNA displays three distinct markers.
that region of southern Italy and formerly Unfortunately, this newly recognised
considered a subspecies of the red squirrel, species is already under threat. In the
as a separate species, with the scientific limited habitat it occupies, it faces
name Sciurus meridionalis. competition from the invasive variable (or
Researchers from the universities of Rome, Finlayson’s) squirrel Callosciurus finlaysonii,
Insubria, Calabria, Florence and Milan introduced from Southeast Asia, which
discovered that the Calabrian black squirrel damages native Italian trees. Roberto Isotti
Dandelions shed
many seeds and
hope for the best.

Some species produce quality
ofspring; others go for quantity;
the rest sit somewhere in
between. At one extreme,
r-strategists (eg dandelions and
salmon) scatter myriad minute Sh e dbug: Andy Sands/naturepl.com; dandelion: Getty; squirrel: A.Cambone & R.Isotti/Homo ambiens; shrimp: Aflo/naturepl.com
progeny, each of which is unlikely
to survive, on wind and tide. At
the other, K-strategists (whales
and coco-de-mer palms) produce
a few fat eggs, seeds or embryos
and nurture them to maturity.
Ks tend to grow bigger and live
longer than rs and dominate them The Calabrian black squirrel
ecologically. But opportunistic, occurs across some 7,000km 2
of southern Italy. Like its
live-fast-die-young rs are adept at
red cousins, it is arboreal,
colonising fresh ground. SB preferring black pines.

104 BBC Wildlife November 2018