Surprise, surprise surprise surprise

Yesterday I was helping to run some training for colleagues. During the indoor session I noticed a Wren dashing rapidly back and forth, as if it was visiting a nest - and when we took our lunch-break, I had a look. There, sure enough was a Wren carrying food up to the edge of the office. More interestingly it was carrying it to an open-fronted nestbox. 'Aha,' thought I, 'this is an opportunity to have a quick butchers at the contents of a Wren's nest without disturbing the nest itself' - wrens tend to build a mossy globe of a nest which you can't check for eggs/nestlings without damaging; something no responsible person wants to do. But, a nest in a nestbox offers a chance to peek in through the front without touching...

Wren (Troglodytes troglodytes) at open-fronted nestbox

...so...

today I remembered to go and check the nest. I scrambled up the ladder with a colleague at the bottom, waiting to watch and laugh catch me if I fell, and to have a quick look at the nest herself. Typically the ladder was a tad too short, so I was balanced a little precariously near the top when I got my line of sight over the rim of the nestbox...

...and....

Big enough to swallow a poor wren!

WHAM! A huge orange gape came lunging out of the nest. At this point I nearly did fall off the ladder - partly though shock, partly through excitement: we have a baby cuckoo which has taken over the Wren's nest on the office! Interestingly, the Wrens seem to have taken over the box from something else themselves - the biter bit, you might say - but it seems to be the Cuckoo which will have the last laugh. I apologise for the shocking pictures, but it's so dark up there as to be almost unworkable, and trying to manually focus a lens whilst balancing on the top of a ladder is not for the faint-hearted, I can assure you.

With a little care and balancing, it was eased out of the nest, ringed, and  returned to the mossy comforts of it's home, where the poor wrens lost no time in resuming their feeding - they'll be worn to a frazzle by the end of this season.

Juvenile - pullus, in fact - Cuckoo. Interesting to note the number of white feathers on the head.

A timely pointer also to some on-going research on the behaviour of Cuckoos: we know next-to-nothing about their migration routes or wintering grounds, so the BTO have begun a project which has satellite-tagged 5 male Cuckoos in East Anglia and is following them through their breeding - and their post-breeding seasons, with some unexpected results already... well worth a look. You can follow - and sponsor - each individual cuckoo if you so wish.

A final point of some vague interest is that this is the second Cuckoo chick we've found on site this year, both attended by wrens - presumably the same female Cuckoo's work. Comfy nest to grow up in, mind.