Breeding and Individual Performance of American Kestrels (Falco Sparverius) in a gradient of agriculture intensification in Central Argentina

GRANDE JUAN MANUEL; OROZCO VALOR, PAULA MAITEN

Skukuza- Kruger National Park

Conferencia; Raptor research foundation conference; 2018

Agriculture expansion and intensification is one of the main drivers of global change. Given their ecological characteristics and role as top predators, raptors could be particularly sensitive to these changes. Here we examine possible consequences of intensified agriculture and rainfall on breeding performance and on individual performance (body condition, pro-inflamatory response, plasma cholinesterase activity) in free- living American kestrels breeding in nest boxes in a gradient from intensified agricultural lands to traditional farming lands and to natural forests in central Argentina. Only breeding success varied among sampling areas, being higher in traditional farmlands with no differences between intensive farmland and natural forest. Breeding parameters were not directly reduced in boxes surrounded by more intensive agriculture, however, the positive effect of pastures on kestrels breeding success, in the context of a regional transformation of pastureland to soybean production suggest that a regional reduction in breeding performance may be occurring for this species. Rainfall had a positive effect on breeding performance except during the chick rearing when it increased nesting failure. Nestling´s body condition and pro-inflammatory capacity shown variation related to factors operating within nest more than with exposure to more intensive areas. In addition, no differences were found in plasma cholinesterase levels between sampling sites and there were many kestrels with the lowest measurable cholinesterase activity levels. This may be because there is no marked exposure to cholinesterase inhibitor pesticides during the breeding period or may be the result of a low capacity of the method we used. Our results indicates that agroecosystems still can provide suitable habitat for raptors related with availability of food o breeding resources. However it is expected that the continuous expansion of agriculture intensification negatively affects demography and we encouraging further study to evaluate how land uses can operate also on health of free living birds.