16 BBC WILDLIFE December 2021
N
o one wants to accidentally step
on a rattlesnake. The snake doesn’t
like it much either. Happily for all
concerned, as it grows, a rattlesnake
accumulates small hollow segments
of each shed skin at the tip of its
tail, which clank together menacingly when
shaken. The result is a warning signal as
archetypal as a wasp’s black-and-yellow
stripes. Increasing the frequency of the
rattle adds to the sense of urgency as
danger approaches. Stuart BlackmanORIGIN
OF PIECES
A rattlesnake’s
rattle
C
hunky greenfinches tend to
dominate feeders, as they come
high in the garden-bird pecking
order, behind only great spotted
woodpeckers and nuthatches
(and ring-necked parakeets, if you
have them). Their visits are extra-special
nowadays, due to a tragic collapse in their UK
population. Greenfinch numbers have fallen
by over 60 per cent since the late 1990s. The
scale of decline first became evident in 2006
in data from people taking part in the BTO’s
popular Garden BirdWatch survey.
Research by the Garden Wildlife
Health project has since shown a link with
trichomonosis, a highly infectious disease
found in doves, pigeons and various other
garden birds. By bringing birds together
at feeders, nature lovers have unwittingly
created the perfect conditions for avian
disease. To help control its spread, clean
feeders fortnightly and report sick birds
at gardenwildlifehealth.org. BHAvian disease strikes
colourful garden visitor
Fall
of the
finches
GREENFINCHES:^ DAVIDTIPLING;RATTLESNAKE:^MICHAEL^ DKERN/NPLGreenfinches love
black sunflower
seeds but feeders
can help spread
diseasesAN ANATOMICAL MISCELLANYLike all snakes,
rattlesnakes don’t
have ears so can’t
hear their own rattle