Malathion applied at standard rates reduces fledgling condition and adult male survival in a wild lesser kestrel population

Abstract

The lesser kestrel Falco naumanni is a globally threatened colonial bird that has suffered a generalized population decline in Europe. Recent studies have suggested that the land-use changes linked to agriculture intensification are the main factors accounting for the population regression. However, there has been little analysis of the role of pesticide applications. In this study, we examined the consequences of a malathion treatment in a wild population of lesser kestrels, specifically its effects on breeding performance, adult survival and population size. We found that the larger the area treated with malathion around the colony, the lower the size and the body condition of the fledglings, although no effects were found on the number of fledged chicks per pair or their sex ratio. Survival of adult males, but not females, was lower in the malathion-treated areas. These results show that organophosphorus pesticides applied at standard rates might disrupt the lesser kestrel population dynamics by reducing their breeding performance and increasing adult mortality in a sex-biased way. The proportional area treated around the colony did not affect colony size in the following year, indicating that an increased adult male mortality was not enough to lead to a detectable population size reduction and/or that the arrival of immigrants could have masked it. Both the direct malathion toxic effects and the expected reduction in prey availability due to fumigation are likely to underlie the observed effects. Hence, keeping non-treated buffer areas around kestrel colony centers should be a strictly applied conservation measure to avoid the observed negative side effects of malathion applications.

Importance of the premigratory areas for the conservation of lesser kestrel: space use and habitat selection during the post‐fledging period

“…great bustard Otis tarda and little bustards Tetrax tetrax ); (3) preventing the application of highly toxic pesticides that may affect both directly and/or indirectly (by reducing prey abundance) to lesser kestrel (e.g. Ortego et al ., 2007); (4) implementing monitoring programmes of summer roosts of lesser kestrel and the investigation of other premigratory areas.…”

An integrated analysis of micro- and macro-habitat features as a tool to detect weather-driven constraints: A case study with cavity nesters

“…Since 2004, we have been monitoring the largest Sicilian population of lesser kestrels nesting in the Gela Plain (Sicily, 37°07'N, 14°19'E; [28, 34], an agricultural landscape extended over 450 km 2 with a mosaic of pseudo-steppes [35]. As in most avian species [10, 11], seasonality affects kestrel reproductive outcome, with late kestrel breeders being less successful than the early ones (unpublished results). Several farmhouses and rural buildings are scattered across the plain with each hosting one kestrel colony.…”

“…In addition to nest characteristics, behavioral traits, such as nest site selection, may represent a valid measure to adopt for mitigating adverse nest conditions when suitable microenviromental features are available [10, 11]. Selection of optimal nest sites are expected to be under strong selection pressure [22, 23, 24].…”

Ecological impacts of early 21st century agricultural change in Europe – A review

“…Insecticide spraying during the yellowhammer breeding season (June/July) may be more detrimental than multiple spraying at other times (Morris et al, 2005). In southern Europe, recent studies have shown that organophosphorous pesticides applied at standard rates might disrupt populations of threatened invertebrate-feeding birds such as the lesser kestrel, due to direct toxic effects and the reduction in invertebrate prey availability (Ortego et al, 2007), though such effects may not be widespread (Vergara et al, 2008). The incidence of poisoning of wild mammals by pesticides decreased in the UK (Barnett et al, 2006).…”