Parthenogenesis, a form of asexual reproduction in which females produce viable offspring without male contribution, is not typically associated with species of birds – more so with amphibians, fish, and reptiles. In fact, it has only been documented in a few species, including domestic chickens and turkeys1. However, a recent study has found that two female California condors in captivity had each produced a chick via this process, despite being continuously housed with males with whom they had previously produced offspring1.
The California condor (Gymnogyps californianus) is a critically endangered bird native to California, whose numbers dropped all the way to 22 individuals in 19821. Thanks to a robust breeding program, the number of California condors in captivity steadily increased, and birds were being successfully released back to the wild – in 2019, there were 219 individuals in captivity and 306 in the wild1. Of course, with such a small starting population there is a genetic bottleneck – a very limited pool of genes available for breeding, which could result in genetic defects. Scientists kept careful track of each bird and its genes to avoid this as much as possible, and this allowed the discovery in 2021 of two chicks which had been produced by parthenogenesis2. The mothers of these chicks had been housed consistently with reproductively capable males, who had fathered many of their other chicks – but not these particular chicks, who were both male and had been released into the wild2. Parthenogenesis is difficult to assess in wild birds because it requires a good understanding of an individual’s genes, as well as their parent(s) and the parents’ genes in order to identify2. The identification of these two chicks as products of parthenogenesis is a step towards better understanding factors that trigger this process in birds, and in establishing it as a mechanism of reproduction in some avian species.
Unfortunately, the two chicks produced by parthenogenesis both died relatively young compared to average California condor lifespans in the wild, and neither were able to father offspring in that time2. Further studies involving more birds produced by parthenogenesis would be necessary to gain a better understanding of how this method of reproduction could impact a bird’s ability to survive in the wild and whether this is a viable option for increasing population numbers for the California condor. However, it’s possible that this may be another mechanism by which population size can be increased in some species including the California condor when access to breeding pairs may be limited.
1 Ryder OA, Thomas S, Judson JM, Romanov MN, Dandekar S, Papp JC, Sidak-Loftis LC, Walker K, Stalis IH, Mace M, Steiner CC and Chemnick LG. (2021). Facultative Parthenogenesis in California Condors. Journal of Heredity 112:569-574.
2 Powell H. (2021). Parthenogenesis In California Condors Stuns Scientists. All About Birds. From https://www.allaboutbirds.org/news/parthenogenesis-in-california-condors-stuns-scientists/