Photographs by DKG
There seem to be lots of robins in the park this year. In fact, there are lots of robins everywhere in Trowbridge. We know that their population in Britain has grown almost 50% since the 1970s but population growth is measured in means and averages, not in sudden seasonal spikes. There could be several reasons for this spike, not all of them necessarily good news for the park.
Robins are ground feeders and the late autumn could have delayed the hibernation of a lot of the invertebrates that robins eat. This would be good news; more invertebrates is usually good news in a ecosystem.
But robins are generalists, they eat all sorts of things, seeds, fruit, toast crumbs, as well as insects. Generalists move into an ecosystem when it can no longer support the specialist feeders. If the park were no longer able to support seed-eaters like bullfinches, or insect specialists like tree creepers, the generalist robins might move into the gap. There might not be enough spiders to support a tree creeper but there are enough for a robin who will make up the shortfall with seeds, rotting crab apples and bacon rind. This is not so good; more robins might mean fewer species.
Something like 40% of fledgling robins don’t usually make it through their first winter. The mild winter might have let more survive until the spring but so might falling populations of sparrowhawks or weasels or any other predator that would prey on a small bird. That would be more bad news for the park.
An ecosystem is a complex web of interrelationships. A robin singing from every tree in the park is an indication that something has changed; what changed and how much difference the change will make, we can’t tell.
. . . a robin singing in every tree . . .