Biología y conservación de la alondra ricotí Chersophilus duponti

Abstract

The Dupont’s Lark is a one of the most iconic steppe-bird in Spain, where occurs the whole European population, because of its extremely shy and secretive behaviour. Here, we review the advances in the knowledge on the basic biology and ecology of this species during the last decade, with special focus on some studies carried out in the peripheral populations located in Rincón de Ademuz (Valencia). The species has undergone a severe population decline throughout the whole Spanish distribution range, with a mean annual decline between 5-10%. Survey method was a key factor to get accurate estimates of population size. Finnish line transects and point counts should not be used for this species. Mapping method, based on four visits, or the line transect (with inner belt of 500 m) are the most suitable counting methods. The right period for surveying the species is between April and June. An analysis of habitat selection at three spatial scales showed that individuals choose flat areas without trees and with large cover of small scrubs (< 40 cm) at micro and macrohabitat scales. At larger scales, patch size seemed the only factor to determine probability of occurrence of the species. Our models of habitat selection predicted successfully species occurrence among sites and years, which suggest that conservation measures proposed for the populations of Rincón de Ademuz may be transferred over larger geographic areas. Fire had a devastating effect on populations. We recorded the species almost extinction in a burnt area within the Layna moorlands (Soria) during the first two years subsequent to a fire that burnt the scrub cover in this area, one of the most relevant for the species in Spain. However, seven years after the fire habitat structure and Dupont’s Lark abundance were almost fully recovered. Our long-term monitoring of the Layna population suggests that fire should not be used as a management tool for reducing scrub cover in patches where the species is already occurring. However, prescribed burning could be indeed integrated into habitat management actions for reducing scrub cover in flat and unoccupied areas to promote spreading from close populations. Dupont’s Lark song in Rincón de Ademuz is strongly influenced by habitat fragmentation, because we found poor repertoires, dialects in each of the studied populations and a decreasing number of songs shared among males over larger distances. These findings suggest that there is no interchange of adult males among populations and that the species might be suffering cultural erosion due to the heavy fragmentation of its populations. During our studies in Rincón de Ademuz and Layna, we also gathered information on the breeding biology and behaviour of the species by monitoring nests, including videomonitoring. Reproductive phenology (end of March to beginning of July) and parameters (clutches of 3-5 eggs, 12 days of incubation, chicks fledge when they are 8 days old, up to three clutches per year) were similar to those previously reported for other Spanish populations. However, we found a relatively high breeding success (40-60%) that suggests that reproductive success would not be leading populations declines in this species. In this work, we provide some recommendations for habitat management and species’ conservation, which can be useful to managers and authorities related to this lark conservation.