Mealworms as a breeding season supplement

CJWildlife is based on a converted farm in Shropshire, a large county in the West Midlands region of England, approximately 80km west of Birmingham.  Most of the surrounding land is intensively farmed for arable crops such as wheat, barley, oil seed rape and potatoes.  Agricultural intensification typically reduces the amount of food available for wildlife and this, along with a lack of nest sites, is thought to be a significant factor in the decline of many once common species.

The UK House Sparrow Passer domesticus population has declined by more than 50% since the 1970s. We have put up over 70 nest boxes specifically to help this species (see separate project ‘The Rea – nest boxes’) but, following a very poor breeding season in 2009 which saw many broods fail and just 38 nestlings ringed, we decided to provide mealworms from March to October to supplement natural supplies of insect food.

In 2010 a record 130 fledglings were ringed, but that record was broken again in 2011 with 222 nestlings ringed.  The mealworms were also taken by birds such as Pied Wagtails Motacilla alba yarrellii, Robins Erithacus rubecula and Blackbirds Turdus merula.  As an experiment we planned to stop providing mealworms when the demand ended, but the House Sparrows have continued to take them throughout the winter.  It will be interesting to see if this has improved the condition of the birds, which we may detect through an earlier start to the 2012 breeding season or an increase in clutch size.