I can identify to species beetle fragments from Little Owl pellets, especially from Britain or Western Europe. I think this will inform feeding habits/ foraging sites of the birds, as well as giving data on the distribution of the beetles. Any birders want to collaborate?
Hi, Max - Glad to see you're interested in this! I've published several papers analyzing the stomach contents of insectivorous birds, most recently of a South American swift. - Henry
Here in New Zealand pellets from the recently extinct laughing owl have revealed the presence on lowland sites on the mainland South Island of large flightless weevils that are now restricted to rat-free offshore islands and mountainous areas. The remains predate the introduction of rodents 800 years ago. Here's a link to an article about it: http://www.tandfonline.com/doi/abs/10.1080/00779962.1996.9722016?journalCode=tnze20
See the excellent work by Grace Servat with species-level identification of stomach contents of birds ... an entree to this work is at http://www.jstor.org/stable/4513770. Also, see museum collections holdings of stomach contents, which could be an excellent source. Not all keep such collections, but many do. ATP
Items like elaterid head capsules and Carabid beetle wing cases remain pretty much intact within the pellet, and you can get some idea of numbers of animals eaten. It is sometimes easier to run pitfall traps to reveal the local fauna and build a reference collection, though as Andrew notes, there are guides to invertebrate bits. You can pick up earthworm parts as well though I do not know how far you might be able to take that to other than broad group level. Possibly one of the most tedious things I have even done.
My working hypothesis, as revealed by recent discoveries of Cymindis and Calosoma beetle populations from bird pellets that had escaped the notice of generations of entomologists- is that the birds are better collectors than we are. My purpose of doing this is to generate records of species not recorded by ordinary collecting techniques, and in exchange the ornithologist will get list of what the bird eats, and by inference from the behaviour of those beetles, where and when it forages..
you might consider e-DNA work on that then, as many taxa have now been bar-coded, especially by the Germans. We got a sequence for a rare elaterid from wood mould recently, so the techniques are now good and cheap per sample. Worth considering.
We had similar project on food source for Coracias garrulus in Latvia. What you have to consider is what bird species are you working on. Coracis garrulus in Latvia is rather localized and we are familiar with from which areas (Coracias feeding areas) insects are coming.
If the target bird species is migratory or covering large areas in search for food, you may find remnants of non-local insects in pellets.
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