I would say that one biotic factor would be the supply of food in the form of insects and snails and one abiotic factor would be the supply of water as water in itself is abiotic though plants can grow in it.
In ecology and biology, the living components of an ecosystem are known as biotic factors. They are distinguished into three groups, that is, consumers of heterotrophs, producers or autotrophs, and decomposers or detritivores. On the other hand, the abiotic factors or components refers to the non-living physical or chemical parts of the environment, which influences living species, and the working of the ecosystems.
In the given case of wood thrush, the biotic factor would be the supply of food in the form of snails and insects, and the abiotic factor would be the supply of water. Both these factors would be critical for the survival of the species.
