Changes in the waterbird community of the Parc National du Banc d’Arguin, Mauritania, 1980–2017

Abstract

Summary The Parc National du Banc d’Arguin in Mauritania hosts the largest concentrations of coastal waterbirds along the East Atlantic Flyway. In spite of this importance, a review of the changes in the numbers of waterbirds in the area is lacking since the first complete count in 1980. Here we analysed the seven complete waterbird counts made since then, and the additional yearly counts made in one subunit (Iwik region) since 2003. We present evidence for changes in the community composition of waterbirds over the past four decades. Total waterbird numbers showed a decrease between 1980 and 2017, with only Great White Pelican Pelecanus onocrotalus showing a significant increase in numbers. Five species showed significant declines: Long-tailed Cormorant Phalacrocorax africanus, Red Knot Calidris canutus, Bar-tailed Godwit Limosa lapponica, Eurasian Curlew Numenius arquata, and Western Marsh Harrier Circus aeruginosus. In the remaining species, the variation in numbers between counts was too large, and the number of complete counts too small, for trends to be detected. The yearly counts at Iwik region also showed sharp decreases in the numbers of Red Knot, Bar-tailed Godwit, and Marsh Harrier, but not of Long-tailed Cormorant and Eurasian Curlew. A multivariate analysis revealed a significant change in species composition over time, which was caused mainly by changes in the species depending on the intertidal mudflats for feeding (generally in decline) vs. the species depending on fish and crustaceans in the sublittoral and offshore zones (often showing increases).

Coastal protection assessment: a tradeoff between ecological, social, and economic issues

“…Toufat is another island in the south of the PNBA that was used in the past by these species to breed before becoming deserted due to extreme flooding events. Furthermore, the local subspecies of the Eurasian Spoonbill, the Mauritanian Spoonbill (Piersma et al 2012), is an endemic breeding bird to the PNBA (El‐Hacen et al 2013) whose population is in sharp decline, continuously decreasing between 1980 and 2017 (Oudman et al 2020). One of the most important nesting sites of this subspecies is on the island of Nair.…”

Microbial communities in developmental stages of lucinid bivalves

“…The exact role of Clostridia in wild birds is still unknown but their occurrence is positively correlated with weight gain [ 91 ] and might influence the survival rates of migratory birds. The occurrence of Clostridia in egg masses could possibly be related to the presence of high numbers of these foraging shorebirds on the intertidal mudflat [ 92 ]. Understanding the functions of the egg mass-associated microbes will require additional studies; however, the known metabolic capabilities of microbes related to members of the egg mass community could shed light upon their successful colonization of the egg masses or help generate hypotheses about their potential functions (for more details see the Supplementary Discussion).…”

Combining Multispectral and Radar Imagery with Machine Learning Techniques to Map Intertidal Habitats for Migratory Shorebirds

“…The cartography of the intertidal habitats produced in this study can be useful for informing several ongoing research and monitoring efforts in the Bijagós Archipelago. For example, the International Waterbird Census [10,117] has been the source of population estimates and trend assessment for migratory shorebird populations in the EAF (see [11]). In the Bijagós Archipelago, these population estimates are produced by partial counts which are then extrapolated for the entire intertidal area [16].…”

“…These birds depend entirely on intertidal areas for foraging during their non-breeding periods [6], where they congregate at low tide to feed on benthic invertebrate prey [7]. Alarmingly, intertidal areas are declining at an unprecedented rate [1], and shorebirds are experiencing widespread population declines [8,9], including in the East Atlantic Flyway (EAF; [10,11]. The causes for these flyway-wide declines are mostly unknown, with insights only for two well-studied species, Bar-tailed godwits Limosa lapponica and Red Knots Calidris canutus, both linked to a reduction in fitness observed in non-breeding areas but caused by global warming effects on breeding sites [12,13].…”