Hi Lisa,

It is difficult to accurately determine human-sourced food given it is often totally digestible. Some items do show up, like wrappers, rubbish etc. that is a useful sign of human-sourced food being ingested. This can be used to show occurrence, which is the usual method used to quantify diet from a sample of scats. Non-prey items that dissolve are usually undetected given the sample preparation usually involves washing scats to leave bone, hair and other solid remains for identification. I have a contact who identifies dietary items in scats who may be able to assist. If you message me I'll forward her details

cheers

Matt

There are also genetic methods to identify prey in scats - although seeing as so much human food is processed and cooked it is not likely to work. I would guess one option is to work from isotopes (hair, bone) from the carnivore......? Certainly not an easy question!

Dear Lisa,

in fact it is a well-known problem. To overcome it, several studies have compared the assimilated diets of individual urban and non-urban carnivores  using stable isotope analysis.  

A couple examples: 

https://www.researchgate.net/publication/274098203_Greater_consumption_of_protein-poor_anthropogenic_food_by_urban_relative_to_rural_coyotes_increases_diet_breadth_and_potential_for_humanwildlife_conflict

https://www.researchgate.net/publication/261930657_Stable_isotopes_evaluate_exploitation_of_anthropogenic_foods_by_the_endangered_San_Joaquin_kit_fox_%28Vulpes_macrons_mutica%29

I hope this helps, best wishes

Danilo

Article Greater consumption of protein-poor anthropogenic food by ur...

Article Stable isotopes evaluate exploitation of anthropogenic foods...