Irrigation and the government irrigation project at Yuma

Abstract

The recent decline of the European starling in northern Europe has been associated with changes in agricultural land-use. We investigated how agricultural land-use affected starling habitat use and home-range size in a heterogeneous landscape in southern Sweden. Breeding starlings primarily foraged in pastures, a habitat with a high availability of potential food for nestlings. When the availability of pasture close to the nest was low, starlings increased their use of other permanently grass-covered habitats such as field margins and ditches. They also spent a larger proportion of their daytime flying because they visited more distant foraging areas. The further from the nest parents foraged, the higher was the probability that they foraged on a pasture. Feeding frequency of nestlings was negatively related to the distance from the nest parents foraged, but no consequences on nestling survival or growth were found. A lower breeding density at low local availability of pasture may compensate for lack of good foraging habitat. It is suggested that recent changes in the agricultural landscape may have increased the mismatch between the availability of good foraging areas and nest-sites. This might have contributed to the recent population decline of the starling in northern Europe by affecting both foraging habitat quality and flight costs paid by parents during breeding.