A new season has started for our researchers at the Bayan Raptor Field Station in Mongolia. The first Saker Falcon eggsappear at our artificial nests in mid-March, while otherfemales do not lay eggs until April, with a month or so typically separating the earliest and latest nests. Older females tend to lay their eggs earlier than younger, less experienced birds, and earlier nesting is associated with larger clutches, higher nesting success and more fledged young. However, in March, night-time temperatures frequently drop as low as -18˚C and day-time temperatures rarely rise above freezing,representing a considerable challenge for incubating falcons to keep their eggs warm. The field teams must also rise to this challenge and Altangerel, lead researcher for our falconproject, has been busy setting up video systems and iButtondata-loggers to study the incubation behaviour of Saker Falcons.
We monitor around 50 breeding pairs of Saker Falcons at ourBayan Raptor Field Station, and each year some of theseadults migrate, typically to spend the winter on the Qinghai-Tibetan Plateau in China, while others remain resident at the artificial nest grid in Bayan. However, a spell of cold, harshweather in January resulted in most of the residents alsoleaving the Bayan area, with our tracked residents moving to milder conditions in southern Mongolia. These movements to unfamiliar areas carry great risks, and one of our tagged birds was predated while seeking refuge in the Mongolian Gobi. Our survey team collected the transmitter amongst featherremains in February.
Understanding the costs and benefits of migration is a key element of Altangerel’s research. Residents, and early returning migrants can start to breed in March but there are costs associated with incubation in such cold conditions,whereas those that return and breed later may find the bestnesting sites already taken. Males that return late, may findthat their mate of previous years have taken up residence with a new partner; such a case of divorce has occurred this spring when a male arrived back in Bayan two weeks after his former mate. Tracking and marking individual birds allows ourresearchers to get such insights into the lives of the SakerFalcon in our study population. Mortality results in new birdsoccupying vacated territories and we have seen the first breeders recruited from the cohort of nestlings ringed in 2023, with the female O90 laying at nearly 3-years old around 200 km from artificial nest where she was reared.
This recruitment illustrates the value of artificial nests for supporting the Mongolian Saker Falcon population, with the nests erected in 2010 still producing thousands of fledglings each year. Nonetheless, many of these metal barrel nestboxes arenow decaying with rust or have fallen over or been removed. We have designed a new style of nesting box, made of durable UV-resistant plastic that comes in a flat-pack that can be assembled on site. We field-tested these boxes over winter and checks in early spring found that they all survived the winter conditions intact. MBZRCF are now embarking on a new phase of deploying artificial nests, targeting conservationof the genetic and phenotypic diversity of the Saker Falconpopulation, with a focus on the “Altai falcons” in western Mongolia.
For media inquiries, please contact malhanaee@mbzraptorfund.org