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House Sparrows: Hedging your bets

Erupting from hedges in a fanfare, chirruping from treetops and speckling the sky with copper flecks, these little birds are stereotyped as drainpipe-cloggers, eave-blockers and mortar-peckers, but I love them! Their twitterings seep through my window, rising from the magnificent, or 'untidy' (depending on your viewpoint) bramble thicket below. Here they squabble over seed, the birdfeeders spinning, the ground underneath awash with a swarm of little brown darts.

​​​​​​Sparrows. At first glance, these feathered fellows appear raucous and food orientated, and this is partly the case. However, as I get to know them, I recognise their character, society and fascinating relationships with others. Amazingly, these fluffed-up brown splodges lead quite complex lives. It is thought a male's position in sparrow hierarchy depends on his bib. This is the black neckerchief which runs from his beak to his breast. Its size will impact his life greatly, as money can in our class-divide ridden world. A high ranking male will sport an impressive, large bib, thus broadcasting his quality and ability to father offspring. Funnily enough (according to the BTO) when a bigger bib was painted onto a sparrow, it strutted around with confidence and attitude - a bit like a teenage boy leaving the barbers with his fresh trim. So, his bib, along with a prize nest, will aid him in finding a mate, and hopefully staying with her for the rest of his life...​​​​​​

But sadly, true love and soulmates isn't all the rave in sparrow romance. It seems that a permanent partner has no benefits other than a yearly mating guarantee. In fact, this 'monogamy' isn't taken seriously - the rate of promiscuity is roughly the same as people.* This is because a female sparrow will readily cheat on her mate, with a male of a higher rank or quality – roughly 15% of fledglings are unrelated to the male raising them!**

She does this not only to produce higher quality offspring, but also an influx of new genetic material reduces the risk of inbreeding in future generations. The male is promiscuous to spread his genes as far as possible.

However, these chirping cheats are very clever when it comes to extra-pair copulation. Instead of mating in public, like they would with their social partner, they find somewhere private, so as not to be seen. The original male may suspect something – he will likely notice that the female is away from him and the nest a lot, especially during mating season. If this is the case, he merely helps out less around the nest, as he knows the young might not be his!

So there you have it. Those chirping chaps, with cute beards and caps, have quite a lot on their plate (and I'm not talking birdfeed)!


**Bird Ecology studies

Thanks for stopping by! And to Emily H for writing this brilliant post!

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