Abstract
BackgroundDiet analysis is essential to understanding the functional role of large bird species in food webs. Morphological analysis of regurgitated bird pellet contents is time intensive and may underestimate biodiversity. DNA metabarcoding has the ability to circumvent these issues, but has yet to be done.MethodsWe present a pilot study using DNA metabarcoding of MT-RNR1 and MT-CO1 markers to determine the species of origin and prey of 45 pellets collected in Qinghai and Gansu Provinces, China.ResultsWe detected four raptor species [Eurasian Eagle Owl (Bubo bubo), Saker Falcon (Falco cherrug), Steppe Eagle (Aquila nipalensis), and Upland Buzzard (Buteo hemilasius)] and 11 unique prey species across 10 families and 4 classes. Mammals were the greatest detected prey class with Plateau Pika (Ochotona curzoniae) being the most frequent. Observed Shannon’s and Simpson’s diversity for Upland Buzzard were 1.089 and 0.479, respectively, while expected values were 1.312 ± 0.266 and 0.485 ± 0.086. For Eurasian Eagle Owl, observed values were 1.202 and 0.565, while expected values were 1.502 ± 0.340 and 0.580 ± 0.114. Interspecific dietary niche partitioning between the two species was not detected.ConclusionsOur results demonstrate successful use of DNA metabarcoding for understanding diet via a novel noninvasive sample type to identify common and uncommon species. More work is needed to understand how raptor diets vary locally, and the mechanisms that enable exploitation of similar dietary resources. This approach has wide ranging applicability to other birds of prey, and demonstrates the power of using DNA metabarcoding to study species noninvasively.
Highlights
Diet analysis is essential to understanding the functional role of large bird species in food webs
Predator species detected Using the MT-RNR1 genetic marker, four host bird species were identified among 45 pellets—Upland Buzzard (n = 26, 23 from Qilian Shan and 3 from Yushu), Eurasian Eagle Owl (n = 15, 14 from Qilian Shan and 1 from Yushu), Steppe Eagle (n = 3, from Dulan County), and Saker Falcon (n = 1, from Qilian Shan) (Fig. 2)
A total of 8 unique MT-RNR1 haplotypes were found for Upland Buzzard, 5 for Eurasian Eagle Owl, 1 for Saker Falcon, and 1 for Steppe Eagle (Additional file 4)
Summary
Diet analysis is essential to understanding the functional role of large bird species in food webs. Morphological analysis of regurgitated bird pellet contents is time intensive and may underestimate biodiversity. Sympatric species with similar ecological demands must find ways to reduce competition. One way this is accomplished is through dietary niche partitioning (Schoener 1974). Understanding this overlap can discern how species allocate resources. Such knowledge is important for conservation planning as communities. Dietary assessment methods for avian species include direct observation (Margalida et al 2005, 2009), camera placement at nest sites (Margalida et al 2005; Tremblay et al 2005), stomach pumping (Wilson 1984; Walter and O’Neill 1986), examination of stomach contents (Miller and McEwen 1995), digestive tract flushing (Moody 1970), forced vomiting (Valera et al 1997), examination of fatty acid and isotope signatures (Iverson et al 2007), molecular fecal analysis (Treves et al 2016; Jedlicka et al 2017; Trevelline et al 2018a, b) and morphological investigation of pellets (Li et al 2004)
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