Drivers for spatial modelling of a critically endangered seabird on a dynamic ocean area: Balearic shearwaters are non‐vegetarian

Abstract

Spatial modelling is an important research tool to improve our knowledge about the distribution of wildlife in the ocean. Using different modelling techniques (MaxEnt and a generalized linear mixed model), a predictive habitat suitability model was developed for one of the most threatened seabirds in the world: the Balearic shearwater, Puffinus mauretanicus. Models were developed using a 10‐year dataset from the Gulf of Cádiz (on the south‐western Iberian Peninsula), a key foraging area for Balearic shearwaters during migration and the non‐breeding season. Predictive habitat maps strongly matched the observed distribution patterns, pointing to bathymetric features as the main modelling drivers. The species was concentrated on shallow areas (up to approximately 100 m in depth) of the continental shelf, very close to the mouth of the Guadalquivir River. In contrast with previous studies, Balearic shearwater distribution in the highly dynamic Gulf of Cádiz was not correlated with areas of high chlorophyll a concentration. This lack of spatial correlation probably arises from the delay between the phytoplankton bloom and the response of the zooplankton and small fish that are preyed upon by Balearic shearwaters, which may result in important displacements of this trophic chain across the Gulf of Cádiz. The analysis presented contributes to a better understanding of the spatial distribution and ecology of the critically endangered top predator in the Gulf of Cádiz and offers important information to improve management plans.

Using long‐term data series to design adequate protected areas that ensure the conservation of inconspicuous small petrel species

“…Based on the previous literature, a set of static and dynamic variables that characterise suitable habitat for ESPs and other seabirds was used (De la Cruz, Ramos, et al., 2021; Hedd et al., 2018; Pereira et al., 2018). Furthermore, since the distribution of ESPs is conditioned by the distribution of their prey (small pelagic fish, small crustaceans and fish larvae; Albores‐Barajas et al., 2011), we used the distribution of zooplankton and micronekton biomass as a proxy for the distribution of ESP prey.…”

“…Much of the information collected through marine surveys is usually carried out in annual campaigns with standardised protocols and methodologies, which gives us the possibility of evaluating the temporal change and the consistency of the species distribution over the years, which is not always stable in migratory seabirds (Paiva et al., 2010). In addition, the analysis of long time‐series databases can improve knowledge about the spatial distribution of seabird species because it includes interannual variability, and by increasing the sample, we can obtain better model performance with more reliable and robust results (De la Cruz, Ramos, et al., 2021).…”