Wild-laid versus captive-laid eggs in the black-bellied sandgrouse: is there any effect on chick productivity?

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.