Alison Hills (2010). "Utilitarianism, Contractualism and Demandingness". Philosophical Quarterly 60 (239):225-242.

This in an Alison Hills' article about utilitarianism and contractualism, where the wild-animal issue is mentioned. The last page is in the second file.

You can download the article here:

http://www.scribd.com/doc/30648958/
http://www.scribd.com/doc/30648950/ (only for the last page)