The survival of gamebird (Galliformes) chicks in relation to pesticide use on cereals

Abstract

Field experiments were carried out to test the effects of cereal pesticides (herbicides, fungicides and insecticides) on chick survival of Grey Partridge Perdix perdix, Red‐legged Partridge Alectoris rufa and Pheasant Phasianus colchicus. On fields in experimental plots the outer 6 m of cereal (the headland) were not sprayed with pesticides from 1 January 1984, whereas control plots were fully sprayed. Gamebird brood counts were carried out after the cereal harvest. In addition, nine Grey Partridge broods were radio‐tracked for 21 days after hatching (four in sprayed plots and five in unsprayed plots) to determine their movements, home range size and survival in relation to pesticide spraying. The mean brood size of Grey Partridge and Pheasant was significantly higher on plots where field edges were unsprayed than on fully sprayed control plots. Data for Red‐legged Partridge were inconclusive. The survival of individually marked Grey Partridge broods was negatively related to the distance moved between successive nocturnal roost sites. Survival was significantly higher, the distance moved between roost sites significantly shorter and the proportion of home range including headland significantly greater for broods feeding in spring barley fields with unsprayed field edges compared with broods feeding in fully sprayed fields.

Population dynamics of the Grey Partridge Perdix perdix 1793–1993: monitoring, modelling and management

“…We believe that the Sussex study and the model which utilized data up to 1978 (Potts 1980) captured all the salient features and causes of the decline of Grey Partridges, not only in the study area up to 1978 but also in the area since then and in studies elsewhere. Experimental evidence has verified the model relationship by relationship (Rands 1985(Rands , 1986, Potts & Aebischer 1989, 1991, Tapper et al 1991).…”

Insecticide use: Contexts and ecological consequences

“…To demonstrate the indirect effects of insecticides at the population level, it is necessary to show that such compounds impact upon food resources in a way that reduces breeding performance or survival. Such a pattern has been shown most convincingly for the grey partridge Perdix perdix (Potts, 1986;Rands, 1985Rands, , 1986, although data showing that pesticides have indirect effects on the available resources and reproductive capacity of other species is also available. Insecticides have been shown to cause a reduction in brood size in yellowhammers (Emberiza citronella) by reducing the number of invertebrate food items available (Boatman et al, 2004).…”

Decline and potential recovery of the European grey partridge (Perdix perdix) population—a review

“…In this way, establishment of weed species and the insects in these unsprayed field margins is stimulated (Hassall et al 1992). The improved insect availability on these conservation headlands increases the chick survival rate (Potts 1986;Rands 1986;Sotherton et al 1993) and the number of grey partridge breeding pairs (Chiverton 1999) compared to fully sprayed cereal fields. Because of the yearly rotation of the soil and the relatively low plant diversity (by ploughing and sowing of cereals), the insect diversity in conservation headlands is not as high as in set-aside fields (Hassall et al 1992), and it does not create the landscape mosaic that is associated with organic agriculture.…”