  Palatability of food is driven by multiple factors like taste, smell,
texture, freshness, etc. and can be very variable across species. There are
classic examples of local adaptations leading to speciation, driven by food
availability. Urbanization across the world is causing rapid decline of
biodiversity, while also driving local adaptations in some species.
Free-ranging dogs are an interesting example of adaptation to a human-dominated
environment across varied habitats. They have co-existed with humans for
centuries and are a perfect model system for studying local adaptations. We
attempted to understand a specific aspect of their scavenging behaviour in
India: citrus aversion. Pet dogs are known to avoid citrus fruits and food
contaminated by them. In India, lemons are used widely in the cuisine, and
discarded in the garbage. Hence, free-ranging dogs, that typically are
scavengers of human leftovers, are likely to encounter lemons and
lemon-contaminated food on a regular basis. We carried out a population level
experiment to test response of free-ranging dogs to chicken contaminated with
various parts of lemon. The dogs avoided chicken contaminated with lemon juice
the most. Further, when provided with chicken dipped in three different
concentrations of lemon juice, the lowest concentration was most preferred. A
survey confirmed that the local people use lemon in their diet extensively and
also discard these with the leftovers. People avoided giving citrus
contaminated food to their pets but did not follow the same caution for
free-ranging dogs. This study revealed that free-ranging dogs in West Bengal,
India, are well adapted to scavenging among citrus-contaminated garbage and
have their own strategies to avoid the contamination as far as possible, while
maximizing their preferred food intake.
