Factors affecting Dupont´s lark distribution and range regression in Spain

Abstract

In this work, we analyse factors explaining the distribution and range regression of Dupont’s lark in Spain, the only European country in which this threatened alaudid is present. Dupont’s lark is an extremely elusive and scarce species, distributed across a reduced and strongly fragmented range, showing a metapopulational structure with unknown dispersive and connective mechanisms. We used maximum entropy modelling (Maxent) on nearly 15,000 Dupont’s lark observations (1985–2015) to assess the probability of presence at a 1 km resolution across its European range. Moreover, we tested the probability of extinction by comparing pre- and post-2000 observations by means of a GLM over a subset of cells with presence-absence data. We obtained strong model fitting (AUC = 0.919), in which species occurrence was explained by low values of plant productivity (NDVI), climate (high temperature range and medium annual precipitation), land use (increasing with sclerophyllous scrubland), flat topography and human disturbance (associated with low human population density). The species also tolerates dry farming, but not other farm types or forest cover. The probability map identified two main regions known as the species' core areas: the steppes of the Iberian System and the Ebro Valley. The North Plateau is characterised by a dispersed structure of small and very fragmented patches of suitable habitat, while a succession of discontinuous probability patches form an Eastern Corridor connecting the central core areas to the southernmost populations. Finally, the model identified small and isolated patches of high probability of presence along the eastern coastline. The species tends to occur in the best available areas but, at the same time, the model revealed a large area of suitable but unoccupied habitat. Our results correct the previous estimation of occupation area from 1,480 to 1,010.78 km 2 , a reduction of 26.22%. The current distribution of Dupont’s lark is almost completely covered by Important Bird Areas (IBAs), highlighting their importance for bird conservation, but only 44.89% is included in Natura 2000 Special Protection Areas (SPAs). A comparison of pre- and post-2000 periods revealed a range contraction of 44%. Probability of extinction increased with higher temperature range and lower annual precipitation, and with decreases in population density, which suggests that this species is extremely vulnerable to both climate change and rural abandonment, due to its dependence on traditional grazing. These results suggest the need for a re-evaluation of the conservation status of Dupont’s lark in Spain. They urge the preservation of not only current extant populations, but also the unoccupied suitable areas that could be critical for metapopulation structure, and the development of policies addressing the preservation of traditional grazing.

Connectivity in Spanish metapopulation of Dupont’s lark may be maintained by dispersal over medium-distance range and stepping stones

“…This work allowed to standardize the field work using the territory mapping census method, which corrects the bias detected in previous works ( Garza, Traba & Suárez, 2003 ; Pérez-Granados & López-Iborra, 2013 ). We considered that pre-2000 observations do not represent current species distribution patterns (see García-Antón et al, 2019 ), and so they were not included in this analysis.…”

“…Isolation of populations is one of the major concerns for Dupont’s larks in Spain ( Garza, Suárez & Tella, 2004 ; Íñigo et al, 2008 ; Méndez, Tella & Godoy, 2011 ). Its fragmented distribution may function as a metapopulation ( Gómez-Catasús et al, 2018 ; García-Antón et al, 2019 ; Traba et al, 2019 ), with different fragments or group of fragments having their own demographic parameters ( Pérez-Granados, López-Iborra & Garza, 2017 ), with individual movements connecting them ( García-Antón, Garza & Traba, 2015 ) and recolonization events of extinct patches ( Bota, Giralt & Guixé, 2016 ). The sample bias toward adult males associated with the capture method ( Garza, Traba & Suárez, 2003 ; Suárez, 2010 ) provides little information regarding other age and sex classes.…”

“…Dupont’s Lark occupies an area of around 1,000 km 2 in Spain, while another 965 km 2 of unoccupied habitat is available ( García-Antón et al, 2019 ), which suggests that the metapopulation may be better connected than expected if this area is used as stepping stones. Recent studies indicate a generalized and pronounced decline in most Spanish subpopulations ( Gómez-Catasús et al, 2018 ) and in their overall distribution ( García-Antón et al, 2019 ).…”

“…Dupont’s Lark occupies an area of around 1,000 km 2 in Spain, while another 965 km 2 of unoccupied habitat is available ( García-Antón et al, 2019 ), which suggests that the metapopulation may be better connected than expected if this area is used as stepping stones. Recent studies indicate a generalized and pronounced decline in most Spanish subpopulations ( Gómez-Catasús et al, 2018 ) and in their overall distribution ( García-Antón et al, 2019 ). As fragmentation of the steppes continues, which is the main threat for Dupont’s Lark ( Íñigo et al, 2008 ), identification of critical patches for the maintenance of the metapopulation connectivity is required for the conservation of the species.…”

A stochastic structured metapopulation model to assess recovery scenarios of patchily distributed endangered species: Case study for a Mojave Desert rodent

“…Critically, while the context of each marsh dictates the emergent properties of the entire system, our modeling approach can indeed be synthetic and generalizable to other patchily-distributed endangered species. Our model and results thus have relevance to many species in metapopulations subject to climate stressors including American pikas (Ochotona princeps), Cabrera voles (Microtus cabrerae), Dupont's larks (Chersophilus duponti), and others [55][56][57][58][59]. A data-driven tool that can synthesize predictions and simulated interventions will be valuable to efficiently and effectively manage the numerous species and communities that depend on conservation intervention if they have any chance to survive.…”