American Kestrels (Falco sparverius) are declining and effective management requires identifying which populations are most vulnerable, where they are most limited, and how climate change will impact patterns of decline. Kestrels are monitored during migration by counting individuals at watch-sites that are stationed along major migratory flyways and these data are used to estimate population trends. However, kestrels are shifting the timing and patterns of their migratory movements, which could make inferring population trends from migration-counts difficult. If we want to maintain the utility of migration-counts into the future, we need to develop methods for understanding which populations of kestrels are being monitored at specific watch-sites during migration, and how migratory movements of those populations are changing over time.
Historically, we have studied migratory connectivity, or the link between specific breeding, wintering, and migrating populations, with long-term banding programs and small tracking devices. However, these methods are limited by low recapture rates, and in some cases can be labor intensive or cost prohibitive. An alternative method is to develop high-resolution molecular markers that will allow us to sample a bird on the wintering grounds, or during migration, and use the DNA from a single feather to map that individual back to its breeding population of origin. For my Master’s thesis, I will work with university researchers, state agencies, and citizen-scientist groups to develop high-resolution molecular markers for creating a spatially explicit map of American Kestrel breeding populations.
The first step for developing molecular tools for population assignment is to identify biologically meaningful populations at spatial scales that are relevant to conservation management. In 2015-2016 we collected high-quality genetic samples from nine locations on the peripheral edges of the kestrel’s breeding range. Then we used restriction-site associated DNA sequencing (RAD-seq) to discover single-nucleotide polymorphisms (SNPs) across the genome of the American Kestrel. Preliminary data suggest we will be able to distinguish kestrels from different parts of their breeding range.
The next step is to develop a panel of SNPs that will allow us to gain information about an individual’s breeding population of origin from the DNA in a single feather. Development of a SNP panel for population assignment will allow us to sample individuals during migration or on the wintering grounds and determine where that individual originated. With these tools, we will be able to monitor kestrels across the annual cycle to determine which breeding populations are declining, where they are most limited, and how climate change will influence the migratory phenology of those populations; information that is critical for effective management of this species in the future.