Role of protected areas for a colonial-breeding waterbird in a fragmented landscape throughout its annual cycle

Abstract

Context: Throughout their annual cycle and life stages, animals depend on a variety of habitats to meet their vital needs. However, habitat loss, degradation, and fragmentation are making it increasingly difficult for mobile species such as birds to find suitable habitats. Wetlands are highly productive systems of great importance to many animals, but their continued degradation threatens their capacity to support different species, including waterbirds. In this context, waterbirds are likely to benefit not only from the creation and management of protected wetlands, but also from the existence of anthropogenic wetlands, managed for economic or recreational activities.

Objectives: We investigated the habitat use of Eurasian spoonbills within an extensive and heterogeneous area in Southern France, and how it varies across the annual cycle and for different age classes.

Methods: We tracked 91 spoonbills of different ages throughout their annual cycle and tested for overall differences in the use of strongly protected areas in Camargue between periods and age classes. Additionally, we identified the main sites used and their management practices.

Results: Our study shows that privately managed wetland areas play a complementary role to strongly protected areas: they may provide spoonbills (and other waterbirds) with suitable foraging habitat at certain periods of the year when these are less available in strongly protected areas.

Conclusions: This study illustrates how the spoonbill, a moderately specialized species, is benefiting from current global changes due to its ability to use suitable habitats, natural and artificial, in fragmented landscapes. Nevertheless, reliance on privately managed wetland areas may have serious consequences for species that are highly dependent on them, and thus, habitat management promoting natural conditions may be crucial to maintain species resilience. It is therefore essential to understand how specific management actions may affect waterbird presence and habitat use, not only to enhance the effectiveness of conservation efforts, but also to promote wetland connectivity and species resilience, particularly in fragmented landscapes.

Supplementary information: The online version contains supplementary material available at 10.1007/s10980-024-02017-5.

Keywords: Areas of strong protection; Hunting pressure; Nature reserves; Platalea leucorodia; Tracking data; Water management.

Fig. 1

Map of the Camargue region along the Mediterranean coast of France, highlighting areas of moderate (orange) and of strong protection (dark green). Areas were classified based on the IUCN categories stated in Table 1. The main breeding colonies in Camargue where GPS tags were deployed are shown (light green) and are all located within areas of moderate protection. White lines are the boundaries of the areas described in Table 1

Fig. 2

Distribution of revisitation fixes (n _{Revisitation fixes} = 1,565,010; n _Ind = 91) across the study area classified according to protection levels: moderate (orange) and strong (green)

Fig. 3

Odds ratios of a revisitation fix occurring according to: protection level (Moderate—Reference); Period (Breeding—Reference); Age (Juvenile—Reference); Protection × Period (Strong × Breeding—Reference); Protection × Age (Strong × Juvenile—Reference). Red colour represents lower odds of revisitation fix occurring when compared to the reference level, while blue colour represents higher odds. The “neutral” line (red vertical line) indicates no effect when intercepted. Horizontal lines indicate 95% confidence intervals. For details check Table S5

Fig. 4

Post-hoc comparisons of estimated marginal mean of total amount of revisitation fixes between levels of protection (Moderate—orange; Strong—green) throughout the annual cycle. Vertical lines indicate 95% confidence intervals after Sidak correction. Different letters indicate statistical differences between groups (p < 0.05)

Fig. 5

Post-hoc comparisons of estimated marginal mean of total revisitation fixes between protection levels (moderate—orange; strong—green) across the different age class. Vertical lines indicate 95% confidence after Sidak correction. Different letters indicate statistical differences between groups (p < 0.05)

Fig. 6

Variation in the average frequency of revisitation fixes (n_{Revisitation fixes} = 1,565,010; n_Ind = 91), throughout the annual cycle according to each period, for each age class (juvenile, immature, and adult). Dashed vertical lines delimitate the different periods: Breeding; Early dispersal; Late dispersal; and Wintering. No fixes during Breeding were considered for juveniles. Shaded-blue area represents standard deviation

Fig. 7

Heat maps of revisitation fixes according to protection levels (moderate—orange dots; strong—green dots), in each period of the annual cycle (rows: breeding, early dispersal, late dispersal, and wintering), and across age classes (columns: juvenile, immature, and adult). The top left map identifies the five most frequently areas across all classes of age and of protection (moderate—orange; strong—green; see text for details)