I live in a bog-standard semi-detached
house in the middle of a long row of similar houses in the centre of Banstead,
when we moved in thirty years ago I was chuffed to find that our house was
blessed with several House Martin nests. Not only that but most houses in
the street had nests and although a few misguided homeowners seemed to enjoy
knocking down the nests as the birds were building (they make such a mess you
know) most appreciated their presence. One of the highlights of the
year was the anticipation of their reappearance in the spring and summer
evenings sitting in the garden were enhanced by watching these birds together
with Swifts hawking insects overhead.
Alas no more, the number of nests dwindled over our
first ten years here until one spring none appeared, a sad year (around 1992).
I also witnessed a similar pattern around my parents home in south
London. Apparently this was a reflection of a much
wider decline across much of northern and central Europe
since the 70s.
Obviously one wondered why! To quote from the
RSPB page devoted to the species and addressing the decline: "They require rain to produce wet mud for nest building and for encouraging the abundance of insect prey, but cold weather prevents them feeding Large-scale mortality is regularly recorded during and after periods of bad weather, during both breeding and migration. On the other hand, hot and dry weather can result in mortality though dehydration and heat stress." This seems to suggest that climate change may be the important factor.
I had always wondered where they found mud for
their nests locally because there was/is precious little surface water or muddy
ponds locally but I am not aware that anything has changed there. In
addition, at spring and autumn migration there are still plenty of birds
passing through, just not stopping!
My opinion (of course I have to have one) is that
their food source (flying insects) has dried up. Bats, Swifts and Spotted
Flycatchers have all shown a similar decline in this area, is it just
coincidence that they all have the same diet?
Of course you have to then address
the disappearance of insects: climate change or farming
practice? Watch this space!
I had to include a picture of a nest, unfortunately not taken locally but in the Mediterranean where thankfully,
there are still large numbers of House Martin and their presence on buildings
are more than tolerated and there are still a lot of insects (although that is
changing year by year in many places).
Great to have you back posting John - and I like rants! House Martins over on my side of Banstead are purely passage migrants now, and even then in small number.
ReplyDeleteThanks Steve, perhaps my general mood will improve but I doubt it!!
ReplyDeleteI am not aware that anything has changed there.
ReplyDelete