Since 1984 pest control operatives in some inner-city areas in the U.K. have found that house mice have become increasingly difficult to control. Mice in these very localised areas have stopped taking rodenticide bait from bait containers, a phenomenon referred to here as behavioural resistance. We report here preliminary experiments designed to characterise the phenomenon more precisely by comparing West Midlands behaviourally resistant (WMBR) populations with non-resistant (BC) populations in Berkshire. We investigated three hypotheses, that compared with non-resistant populations, resistant mice 1) are less likely to enter conventional live-capture traps; 2) have unusual food preferences; and 3) avoid bait boxes. Longworth, Sherman and 'Tichy' traps were all less successful at resistant sites, the Longworth being ineffective and the Sherman almost so. WMBR mice also avoided Longworth traps more than BC mice in small-scale laboratory experiments designed to exclude environmental differences. A field trial showed that resistant mice much prefer peanut butter and Test Food 3 (which cannot be named for commercial confidentiality) to canary seed and Betalard (a proprietary rodenticide), but in this trial bait boxes were not avoided more than bait trays.

There is accumulating evidence that macroevolutionary patterns of mammal evolution during the Cenozoic follow similar trajectories on different continents. This would suggest that such patterns are strongly determined by global abiotic factors, such as climate, or by basic eco-evolutionary processes such as filling of niches by specialization. The similarity of pattern would be expected to extend to the history of individual clades. Here, we investigate the temporal distribution of maximum size observed within individual orders globally and on separate continents. While the maximum size of individual orders of large land mammals show differences and comprise several families, the times at which orders reach their maximum size over time show strong congruence, peaking in the Middle Eocene, the Oligocene and the Plio-Pleistocene. The Eocene peak occurs when global temperature and land mammal diversity are high and is best explained as a result of niche expansion rather than abiotic forcing. Since the Eocene, there is a significant correlation between maximum size frequency and global temperature proxy. The Oligocene peak is not statistically significant and may in part be due to sampling issues. The peak in the Plio-Pleistocene occurs when global temperature and land mammal diversity are low, it is statistically the most robust one and it is best explained by global cooling. We conclude that the macroevolutionary patterns observed are a result of the interplay between eco-evolutionary processes and abiotic forcing.