Meadow yellow

Meadow yellow
Bulbous Buttercup (Ranunculus bulbosus) in a Devon meadow

Wednesday, 27 October 2010

The Upside-down bird

We recently started feeding our woodland birds again after a summer break, and within hours of filling peanut & fat ball hangers they were back as if there had been no break in supply. The feeders are being dominated by the tits, including; Great, Blue, Long-tailed, Coal & Marsh. Many of these are likely to be new to the ‘Pinfold cafĂ©’ after last year’s harsh winter.

The tits have been joined this autumn by at least two regular Nuthatches (Sitta europaea). I’ve seen these birds many times scurrying up and down tree trunks, but I’ve become intrigued recently by their apparent preference for feeding upside down, particularly on the hangers. This reverse mode is relatively unique to Nuthatches. Their natural foraging technique involves working their way down tree branches looking for invertebrates, before flying to the top of another tree and repeating the exercise. The only explanation that I can find for such novel feeding is that by adopting a different approach they see invertebrate prey that other birds, such as woodpeckers and treecreepers, overlook from more conventional angles. Nuthatches appear to be aided by having an extra-large and stronger hind toe (hallux) for gripping the trunk at tight angles, and a stubby tail to reduce a potential incumbency. Perhaps they get so used to this productive technique that they continue to feed upside down on hangers through habit rather than efficiency. Their characteristic posture on the hanger is body facing downwards but frequently looking upwards checking for threats (see photo), making for a rather rubber-necked pose.

It is therefore no surprise that due to the modus operandi of the Nuthatch, that they are frequently known as the ‘Upside down bird’. Other species of Nuthatches from around the world feed in a similar way, which have prompted other nicknames, including Topsy-turvy bird, and Devil down-head.

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