Effect of eggs origin and age on chick productivity in the Black-bellied Sandgrouse

Aourir, M., Znari, M., Radi, M., & Melin, J.-M. (2013). Wild-laid versus captive-laid eggs in the Black-bellied Sandgrouse: Is there any effect on chick productivity? Zoo Biology doi:10.1002/zoo.21095 (early view)

Abstract:

Because survival in captivity is a significant determinant of birds available for release and reinforcement of wild populations, we aimed to identify sources of variation in mortality to assess potential impacts of management on chick productivity. We analyzed characteristics of Black-bellied Sandgrouse eggs collected from the wild and produced by captive pairs. Wild laid-eggs and pulled captive-laid eggs were incubated artificially and all chicks were hand-reared until seven weeks of age. Wild-laid eggs were significantly bigger, heavier, and denser than captive-laid eggs which showed a higher variability in size. Fertility, embryo mortality, and fertile egg hatchability were similar for wild-laid and captive-laid eggs (67.92% vs. 68%; 15.62% vs. 15.7%, and 80.55% vs. 84.44%, respectively). There were significant positive relationships between egg weigh/volume and chick hatch weight. Mortality of chicks hatched from wild-laid eggs was much lower than that of chicks from captive-laid eggs (19.44% vs. 60.5%) during the first week after hatching, but decreased and being nil from the third week. Heavier hatchlings from captive-laid eggs exhibited higher survival rates which is not the case of hatchlings from wild-laid eggs. These latter hatchlings had higher survival rates increasing with the age of eggs in relation with the period of natural incubation. The recommended age at which wild-laid eggs could be collected is at least 13 days for full chick survivability. We concluded that in our experimental captive breeding program of the Black-bellied Sandgrouse, productivity of viable hatchlings was much better from wild-laid eggs and as later as these were collected.

Black-bellied Sandgrouse (Pterocles orientalis)

Black-bellied Sandgrouse Pterocles orientalis. (Joaquim Coelho on flickr, licence: CC-by-nc-nd)

Habitat selection and partitioning of the Black-bellied Sandgrouse, the Stone Curlew and the Cream-coloured Courser in arid areas of North Africa

Traba, J., Acebes, P., Malo, J. E., García, J. T., Carriles, E., Radi, M., & Znari, M. (2013). Habitat selection and partitioning of the Black-bellied Sandgrouse (Pterocles orientalis), the Stone Curlew (Burhinus oedicnemus) and the Cream-coloured Courser (Cursorius cursor) in arid areas of North Africa. Journal of Arid Environments 94: 10-17.

Abstract:

Niche theory predicts that coexisting species with similar trophic requirements should demonstrate resource partitioning, particularly where resources are scarce. Conversely, this is not expected between species that do not share primary resources. This study analyses the patterns of spatial coexistence and habitat selection, on two spatial scales, of three species of semidesert regions in Morocco: the Black-bellied Sandgrouse (Pterocles orientalis), the Stone Curlew (Burhinus oedicnemus) and the Cream-coloured Courser (Cursorius cursor). Co-occurrence analysis results point to between-species segregation on a macrohabitat scale. Hotelling’s T test of the species-presence data showed a pattern of macrohabitat selection that diverged from habitat availability for the three species with differences among them. Both the classification tree and the pattern of microhabitat selection obtained by model averaging showed scant overlap between the Sandgrouse and the Courser, suggesting habitat partitioning between them on a fine scale. Our results confirm spatial segregation of the three species, especially between species with different trophic strategies: the Sandgrouse versus the Stone Curlew and the Courser. The latter two species were best segregated on a microhabitat scale, supporting the conclusions that macro- and microhabitat selection are major factors in bird community configuration in arid ecosystems and contributing to reduce potential competition.

Highlights:

► The three steppe-bird species show a low level of overlap at the macrohabitat scale.

► Granivorous species shows habitat segregation from insectivorous ones at macro and microhabitat.

► Insectivorous species show habitat partitioning only at microhabitat scale.

► Segregation is mainly based on abiotic factors such as topography and surface structure.