Abstract
The Madagascar Jacana Actophilornis albinucha (Jacanidae) is an endemic shorebird found in the threatened wetlands of western Madagascar. This species is presumed to exhibit classical polyandry; however, few data are available to support that assumption. More generally, a lack of basic understanding of this species hinders conservation efforts. We conducted the most extensive study of the Madagascar Jacana to date, and report on its: 1) distribution, population size and density; 2) degree of sexual size dimorphism; and 3) phylogenetic position. The surveys were conducted at 54 lakes, between January and October in 2016. Madagascar Jacana were found at 22 lakes, and within these were distributed at a mean density of 3.5 ± 0.74 [SE] individuals per hectare of surveyed habitat. We estimate the global population size to be between 975 and 2 064 individuals, and habitat destruction appears to be the main threat to the species. Females were significantly larger than males, consistent with reports for other Jacanidae species. Using a mitochondrial DNA fragment, we expanded the Jacanidae genetic phylogeny, and confirmed that Madagascar Jacana is the sister species to the African Jacana Actophilornis africanus. Further studies are urgently needed to thoroughly re-assess the threat status and population trend of the Madagascar Jacana.
Highlights
In the biodiversity hotspot of Madagascar (Myers et al 2000), freshwater wetlands are considered a highly threatened habitat owing to land-use changes, conversion to rice paddies (Benstead et al 2003; Kull 2012; Bamford et al 2017)
This study provides the first detailed account of Madagascar Jacana, an understudied endemic shorebird restricted to freshwater wetlands of Madagascar
Reversed sexual size dimorphism By combining genetic sexing with morphometric data we show that females are significantly larger than males, confirming previous findings of sexual size dimorphism (SSD) in Madagascar Jacana using a small sample size (Jenni 1996; Safford 2013)
Summary
In the biodiversity hotspot of Madagascar (Myers et al 2000), freshwater wetlands are considered a highly threatened habitat owing to land-use changes, conversion to rice paddies (Benstead et al 2003; Kull 2012; Bamford et al 2017). As highlighted by the most-thorough assessment of the freshwater biodiversity of Madagascar to date, 43% of the species inhabiting this ecosystem are currently considered threatened (Máiz-Tomé et al 2018). The distribution of the Madagascar Jacana stretches almost the entire length of the western wetland region (Safford 2013) (Figure 1); the predicted range is based on records that are out of date (some are from more than 100 years ago), and may be inaccurate. The lack of basic knowledge of this species is hindering further research and conservation efforts, which require up-to-date estimates of distribution and population size (IUCN 2001; Buckland et al 2008)
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