The Blackbird's Nest

We we are at the Norwegian Church in London recently and, after the boys had completed their studies and eaten lunch, we ventured into the back garden for a bounce on the trampoline and kick of the football. 

Glancing across to the ivy, I suddenly caught sight of a bird nest constructed in an unusually low and exposed position. Indeed it was receiving some interest from the local avians, which can't have been ideal. 

The kids were keen to take a closer look at the nest and, seeing as it was so low, it wasn't difficult to hoist them into an ideal viewing position. We were very careful not to disturb the nest and I snapped the close-ups by holding the camera directly above and avoiding direct contact. 

Checking the books it would appear this was a Blackbird's nest (the blueish background and vague brown speckles being indicative), but a close call between that and a House Sparrow. The latter seems to have a more pronounced contrast between the brown and blue.  Hard to tell if the eggs had been abandoned, but there were some signs of pecking, which is commonplace during spring, as other species attempt to reduce the competition for food. Either way we left them in peace - carried in the capable hands of mother nature. If any are destined to hatch and thrive then it will happen, otherwise they may provide a useful food source for other creatures in the area. 

Nests are truly miraculous creations. They are right up there with spiders' webs in the complexity stakes and every species of bird builds a nest in a unique fashion. Remarkable that thousands of years have rendered these skills instinctive and thus provided a multitude of birds with the best chance of survival.

It would be wrong to suggest, however, that all bird nests are complicated structures. Many are nothing more than a dent in a sand pile or a scoop from a pile of rotting vegetation. Others are incredibly intricate - species such as the Weaver finch (Ploceidae) construct hanging nests with various chambers. Swallows (Hirundinidae) utilise mud to establish well protected nests, often located in precarious positions on the edge of cliffs, drain pipes or even high up on adjoining walls (see below). 

Evolution of nest building will have been dictated by a number of factors, including available substrate, intra-specific competition and predation levels. There are many examples of convergent evolution, which we would expect to see and, consequently, many species build superficially similar structures. 

Bird nests aside there are many examples of external construction in the animal kindgom - ranging from Caddis fly larvae and their armoured mobile homes to termite mounds and spider webs. Utilising the environment, huge numbers of creatures have honed techniques until reaching a point where their kind has the best possible chance of survival and reproduction. We walk down the street everyday and pay no attention to the wonders that have been designed above our heads, but take a closer look and the average bird nest is one of the most amazing things you are likely encounter.