The California condor can reproduce asexually

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.

California condor. Photo by Patrick Sysiong, from

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

The Mauritius kestrel is adjusting its phenology according to temperature changes

Photo credit: Willard Heck, retrieved from The Peregrine Fund,

As global temperatures warm, many species must make adjustments to their range or the timing of life-history events in order to continue to survive and reproduce in a changing world. Some species are considered more vulnerable to these changes, including species native only to islands because their limited range increases the risk to populations from climate events and they have a limited ability to disperse (Taylor et al. 2021). This greatly limits their capacity to adapt to climate change by relocating to a more suitable location with favorable conditions. As such, the only likely way to adapt to climate change for many island-endemic species is through phenotypic plasticity, by which animals alter the timing of life-history events such as reproduction (Taylor et al. 2021).

One such species is the Mauritius kestrel (Falco punctatus). This small bird of prey, native only to the small island of Mauritius in the Indian Ocean, was once the most endangered bird of prey in the world, with a population in the 1970s consisting of only two known breeding pairs, causing a genetic bottleneck where the existing gene pool was extremely limited (Jones et al. 1995). Thanks to repopulation efforts over several decades, the Mauritius kestrel made an incredible recovery and population estimates indicate there are now over 800 individuals (Jones et al. 1995). These birds of prey breed beginning in the dry spring, raising their young as the warm rainy season begins in the early summer (Taylor et al. 2021). But climate change could drastically alter seasonal patterns in Mauritius and put wild populations at risk of declining once more.

A new study published in 2021, however, shows that Mauritius kestrels may have a better chance of adapting to climate change than previously believed. Taylor et al. (2021) tracked rainfall patterns and breeding phenology of Mauritius kestrels between 1962 and 2016, along with other measures of breeding success. Between 1994 and 2014, the study found that the first egg-laying date advanced by about 0.7 days per year, influenced primarily by the mean temperature in the three-month period of July-September (Taylor et al. 2021). Additionally, Taylor et al. (2021) found that overlap of the rainy season with the breeding period had a negative impact on breeding success, favoring earlier breeding. Despite having experienced near-total extinction and an extremely limited gene pool, the population has retained phenological responses that are sufficient for it to track these environmental changes and adapt (Taylor et al. 2021). The Mauritius kestrel demonstrates phenotypic plasticity by adjusting its breeding period as temperatures increase, which may allow it to better adapt to changing environmental conditions despite being an island species that are considered to be more vulnerable to these same changes.


Taylor J, Nicoll MAC, Black E, Wainwright CM, Jones CG, Tatayah V, Vidale PL and Norris K. (2021). Phenological tracking of a seasonal climate window in a recovering tropical island bird species. Climatic Change 164:n.p.

Jones CG, Heck W, Lewis RE, Mungroo Y, Slade G and Cade T. (1995). The restoration of the Mauritius Kestrel Falco punctatus population. IBIS 137:173-180.

The Peregrine Fund. (n.d.). Mauritius Kestrel. Retrieved 5 March 2022 from