Friday, 1 July 2016

Birds and the weather


No birds of note to report today and at one stage I thought it would be the first day for ages without rain. However it loomed very dark here this evening and we experienced a series of very heavy showers. It might be just an inconvenience to us, but to just fledged young passerines a drenching late in the evening followed by a cool night can be enough to chill and kill. 

Preliminary observations suggest that some birds have enjoyed this very wet spring and early summer. Birds that need to probe for invertebrates require at least moist conditions in order to reach their food. Starlings are much reduced in numbers these days but my impression is that they have enjoyed a productive year with plenty of juveniles on the wing. Leatherjackets, the grub stage of the Cranefly family, are a critical food item for the Starling and it seems that the adults found plenty of them to provide for their nestlings. It is probably a similar story with the Rook, another bird that probes the surface for grubs and similar, and the flocks now out in the fields seem to include plenty of juveniles.

Other members of the corvid family also breed well in damp springs when invertebrate prey is important for the breeding success of Magpies, Carrion Crows and Jackdaws. Although all these species can be predatory towards smaller birds, it is invertebrate prey which ensures success and makes up the majority of the food.

Generally Blackbirds and thrushes breed well in moderately wet conditions, but such is the extent of the rain it is likely many of the fledged young have chilled and not survived. The first couple of broods are also staple food for birds of prey, larger birds and mammalian predators and few survive. Later broods stand more chance when predators have less pressure to feed young of their own. Robins are a smaller prey item and less readily sought out by predators such as Sparrowhawks, and they seem to be having a good 2016 (2015 was good for them too). Wrens enjoyed a great season last year and this year indicates there are record numbers of breeding pairs but productivity is very low. Building moss nests which soak up rain like a sponge will not have helped. However there have been plenty of calling just-fledged juveniles about, but the rain and cool nights compromises their limited feathering and small size and many seem not to be surviving for very long.

For those species that attempt a couple of broods, there is still plenty of time for breeding success. The tits in general do not normally double brood (occasionally Great Tits do), so we know already that yet again it has been a poor breeding year for them.

The pretty constant high water level at Pitsford Reservoir appears to have benefited those species that nest on the water or in the margins with good numbers of Coot families and even several Mute Swan families too. Time will tell if species that tend to breed later (such as the Great Crested Grebe and Tufted Duck) will do as well.

Every year there are winners and losers and no two years are the same, and despite adverse conditions, it is always amazing how many young birds survive and join the ranks to ultimately breed themselves.


Neil M

A nestful of Swallow chicks!
When it's wet outside there is a
significant advantage when your
parents have created a nest for you
inside a building! These birds will
probably fledge this coming week-end.

Image courtesy of Chris Payne.

Adult male Starling. The blue
base of the bill in the breeding
season identifies it as a male. And
you guessed it, the female has a pink
base to the bill!

Juvenile Starlings.

Adult and juvenile Rook.

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