Musical accompaniment: Philip Glass: Circles, played by Arturo Stalteri on the piano.
Since I wrote about the possible impacts of deer overpopulation on forest snails and slugs, I have done additional reading, including the following 2 papers. Incidentally, I found pdf versions of both of these papers on the Internet, but didn't note the addresses. If you search for them you can probably find them too.
Rooney TP and DM Waller. 2003. Direct and indirect effects of deer in forest ecosystems. Forest Ecology and Management 181:165 176.
This is an informative review, but I am not going to discuss everything in it. One thing that I found interesting is the authors' suggestion that the response of some forest plants or animals to deer could be non-linear. For example, curve B in the figure from the paper (below) shows a hypothetical taxon whose abundance is at a maximum at an intermediate deer density.
Cote SD, TP Rooney, JP Tremblay, C Dussault & DM Waller. 2004. Ecological impacts of deer overabundance. Annual Review of Ecology Evolution and Systematics 35: 113-147.
This is also a useful review that stresses more or less the same points as the previous paper. The authors point out that although deer populations in North America have undoubtedly been growing, it is not known if the present deer populations are higher than those before European colonization. They also mention that large herbivores, such as deer, through heavy browsing can move forest plant communities from one stable state to another and that these alternative stable states are not readily reversible when the browsing pressure is reduced.