CANCELLED - Squirrels alter their activity in cities in response to competition between species

Background/Question/Methods

Urbanization leads to rapid, often irreversible alterations to the natural habitat, and the wildlife inhabiting cities are subjected to new challenges never before encountered. Changing behaviour in response to new environments in cities can make individuals more successful and may facilitate species persistence in urban habitats. For example, altering the timing of their daily activities is one of the ways animals respond to new challenges and could be one of the mechanisms enabling animals to colonize cities, yet studies investigating activity changes in cities, particularly in mammals, are still rare. We studied the differences in the activity patterns of eastern grey (Sciurus carolinensis) and North American red squirrel (Tamiasciurus hudsonicus) populations between urban and rural areas. We were particularly interested in differences in the daily activity patterns of squirrels between urban and rural areas and differences in activity between the two species. To do this we simultaneously monitored the activity of grey squirrels and red squirrels using passive integrated transponder tag data loggers placed in urban and rural sampling sites.

Results/Conclusions

We found differences in the temporal activity patterns of squirrels, presumably caused by the environmental differences between urban and rural areas and competition between species. There was high overlap in activity between red and grey squirrels in cities and rural areas, however, the peaks in foraging activity for both species generally arose when the other species were less active. This is suggestive of grey squirrels adjusting the time of their daily activities to avoid the more territorial and aggressive red squirrels. Additionally, both urban grey and urban red squirrels started foraging earlier than their rural counterparts, perhaps due to altered light levels between urban and rural areas, but this varied during different months and between species. Overall, our results show that both abiotic and biotic mechanisms may alter the temporal activity of squirrels in cities and that behavioural adjustments may facilitate the persistence of squirrel populations in urban environments. This knowledge is important as cities continue to grow at an unprecedented rate and we need to know the ways animals adjust their behaviour to tackle the new challenges they face.