Foraging Habitat Quality Constrains Effectiveness of Artificial Nest-Site Provisioning in Reversing Population Declines in a Colonial Cavity Nester

Abstract

Among birds, breeding numbers are mainly limited by two resources of major importance: food supply and nest-site availability. Here, we investigated how differences in land-use and nest-site availability affected the foraging behaviour, breeding success and population trends of the colonial cavity-dependent lesser kestrel Falco naumanni inhabiting two protected areas. Both areas were provided with artificial nests to increase nest-site availability. The first area is a pseudo-steppe characterized by traditional extensive cereal cultivation, whereas the second area is a previous agricultural zone now abandoned or replaced by forested areas. In both areas, lesser kestrels selected extensive agricultural habitats, such as fallows and cereal fields, and avoided scrubland and forests. In the second area, tracked birds from one colony travelled significantly farther distances (6.2 km ±1.7 vs. 1.8 km ±0.4 and 1.9 km ±0.6) and had significant larger foraging-ranges (144 km2 vs. 18.8 and 14.8 km2) when compared to the birds of two colonies in the extensive agricultural area. Longer foraging trips were reflected in lower chick feeding rates, lower fledging success and reduced chick fitness. Availability and occupation of artificial nests was high in both areas but population followed opposite trends, with a positive increment recorded exclusively in the first area with a large proportion of agricultural areas. Progressive habitat loss around the studied colony in the second area (suitable habitat decreased from 32% in 1990 to only 7% in 2002) is likely the main driver of the recorded population decline and suggests that the effectiveness of bird species conservation based on nest-site provisioning is highly constrained by habitat quality in the surrounding areas. Therefore, the conservation of cavity-dependent species may be enhanced firstly by finding the best areas of remaining habitat and secondly by increasing the carrying capacity of high-quality habitat areas through safe nest-site provisioning.

Assessing the importance of High Nature Value farmlands for the conservation of Lesser Kestrels Falco naumanni

“…Cereals have little demand for pesticides and are, mostly, nonirrigated in Greece (EEC 2007). The results agree with the findings of other lesser kestrel studies in the Iberian Peninsula where the species occurrence is associated with extensive cereals, a habitat related with the abundance of preferred prey, mainly during chick-rearing period that is crucial for the species reproductive success (Doňazar et al 1993;Parr et al 1995;Bustamante 1997;Tella et al 1998;Rodríguez et al 2006;De Frutos & Olea 2008;Catry et al 2013;Rodríguez et al 2014;Hernán-dez-Pliego et al 2017). Thus, Lesser Kestrels could stand as a biodiversity surrogate and as an umbrella species for delivering farmland biodiversity conservation in the agro-ecosystems of Greece.…”

“…However, researchers argue that habitat associations based on landscape patterns could influence the distribution of species, improve the accuracy and ease the use of models (McGarical & McComb 1995;Lawler & Edwards 2002). Typical HNVf such as grasslands and fallow land when located in the vicinity of lesser kestrel colonies are considered as important foraging habitats for the species, being rich in prey availability (Doňazar et al 1993;Parr et al 1997;García et al 2006;De Frutos et al 2010;Catry et al 2012Catry et al , 2013. However, they were not identified as significant predictors in this analysis.…”

“…Philopatry of birds for building colonies in areas previously covered by suitable habitats could explain the selection of this habitat despite its low foraging quality (Bustamante 1997). As birds do not have territorial restrictions, they can fly long distances to forage when there are no suitable habitats close to colonies or food is insufficient García et al 2006;Bonal & Aparicio 2008;Catry et al 2013). Other studies show, however, that birds are negatively associated with irrigated crops such as maize (Ursúa et al 2005;De Frutos & Olea 2008;De Frutos et al 2010;De Frutos et al 2015).…”

Estimating Fractional Shrub Cover Using Simulated EnMAP Data: A Comparison of Three Machine Learning Regression Techniques

“…This led to an intensification of agricultural production on fertile soils and to the abandonment of formerly cultivated poor soils [34,35]. Shrub encroachment on the abandoned farmland threatens the fragile regional ecosystem [12] and leads to heterogeneous patterns of shrub cover densities dominated by rockroses (Cistus spp.…”

Effects of variation in breeding habitat on Ring OuzelTurdus torquatusproductivity and chick condition

“…Spatial and temporal heterogeneity in bird breeding habitat can cause variation in individual productivity and survival, and thus variation in demographic parameters (Donovan et al 1995, Paredes et al 2012, Aubry et al 2013, Catry et al 2013) and population size (Holmes & Sherry 2001, Amar et al 2011. Anthropogenic changes in habitat extent and quality have been the most important cause of declines in terrestrial biodiversity, particularly birds, in the past century (Sala et al 2000, Green et al 2005.…”