14 July 2016
Barn Swallows at SpruceHaven
As was to be expected our colony of Barn Swallows Hirundo rustica is starting to produce second clutches, the young from the first nest now having been left to fend for themselves.
Yesterday, nest No. 67 had a bird sitting on it, and following the night's substantial rainfall, others were outside gathering mud and grass to refurbish existing nests or construct new ones.
We have had little rain this summer and I am sure that the 25 mm or so that we just received was a major stimulus in initiating renesting behaviour.
Our colony had around twenty active nests for the first round of nesting and we will be watching to see if all those nests are reoccupied and whether any additional nests are built. We will also be checking to see whether any of the old nests that were not used on the first go around are occupied for a second brood. It is a shame that we have no way of knowing whether the same pair will reoccupy the nest they used for their first brood.
Insects were present in substantial numbers yesterday, of various types, and I am sure that the abundant food supply will also spur on the birds to nest again. Barn Swallows are eclectic in their choice of food and are known to take large flies of the family Muscidae, hoverflies, horseflies and robberflies, smaller acalypterate flies and nematoceran flies. Aphids and other plant bugs form a significant component of the diet, with beetles, parasitic Hymenoptera, bees, moths, mayflies, dragonflies, grasshoppers, lacewings and caddisflies also. Barn Swallows do not hesitate to brush past foliage to pick off caterpillars and skim across the surface of the water to snare insects in flight. The pond at SpruceHaven, right next to the barn where the swallows are breeding, is seldom without several birds feeding at the surface.
All the conditions are right for a successful second batch of young swallows and our entire team is looking forward to continuing to monitor this important colony.
Reference used: Swallows and Martins (1989), Angela Turner and Chris Rose, Houghton Mifflin Company, Boston, MA, USA