Effects of habitat management can vary over time during the recovery of an endangered bird species

Abstract

Time and financial constraints often force conservationists to make ad hoc management decisions without sufficient knowledge to predict their effects. In particular, the effects of management on reproduction and survival are rarely evaluated and habitat dynamics are rarely taken into account. We evaluated the effects of three different forms of habitat alteration on the endangered Pale-headed Brushfinch (Atlapetes pallidiceps) in Ecuador during the phases of population increase and stabilization. More specifically, we monitored the effect of a natural experiment with three approaches (clearing, grazing and burning) to preserve the semi-open habitat of this species on the reproductive success of 220 breeding events over seven years and on the survival of 73 adults over three consecutive years. Habitat alteration had contrasting effects on reproduction and survival. All approaches increased the number of fledged chicks per breeding event while the population stabilized, but not while it increased. However, vegetation burning reduced survival probability of adult individuals. In addition, survival was strongly correlated to the presence of water in the territories. Overall, we revealed that the negative effects of vegetation burning on survival overrode the positive effects on reproduction, and could—if implemented at a larger scale—destroy the conservation aim of increasing the population size. Importantly, we show that the effectiveness of management differs depending on the actual population trend. Our study therefore shows that the a posteriori evaluation of ad hoc vegetation control can constitute an integral part of adaptive management and thereby also of long-term conservation planning of endangered species.