Tis the season for…. chasing one’s neighbour up a tree

Grey Squirrel London

Keeping a beady eye on the neighbours! During a recent Wild Capital wildlife walk at Fulham Palace, we observed grey squirrels communicating through motions, postures, vocalisations and chases. Here an individual enjoys an acorn in a quiet moment.

As autumn fades into the shorter days of winter, squirrels have lots on their minds. There are nuts to bury, the drey to reinforce for winter and if that wasn’t enough to think about, this is the squirrel social-climbing season.

Squirrels have a subtle, but well respected and maintained social hierarchy. Each adult squirrel lives within a territory, but areas within that territory are not exclusive; squirrels overlap their territories with those of their neighbours. This has the potential for all kinds of neighbourly bickering. What if two squirrels both want a particularly tasty acorn which happens to fall in the shared area? Who moves out of whose way?  How do they decide who gets the best drey site in a shared tree?  Well in a squirrel neighbourhood there are two possibilities; have the same old argument every time neighbours cross paths, or establish from the outset who has the upper hand.  At some point in their behavioural evolution squirrels have opted for the second choice. They establish a dominance hierarchy, which includes all the squirrels resident in the neighbourhood. Once the top-dogs and under-dogs, or squirrels rather, have been established then the local population generally respects this ordering, and future conflicts are much reduced.

Late autumn is the time that the social hierarchy is re-established each year, probably because this is the time that young squirrels born earlier in the year, and sometimes adults too, are dispersing looking for a territory within which to settle. It’s a bit of a neighbour shake up and therefore the ideal time to work out exactly who is who, and who is boss.  Top of the pile will be a dominant male, followed by subdominant males, dominant and subdominant females and finally at the bottom of the heap, the youngsters.  So an individual’s status is related to both sex and age, with social standing rising with age. In the squirrel world “respect your elders” is law!

So how exactly is a squirrel neighbourhood social structure enforced? The actions are mostly understated and often go unnoticed by us humans. Squirrels are masters of subtle communication and a flick of the tail, a discreet “chuck”, a rising of hair or an elevated walk can all spell out “I’m boss over you”.  Grey squirrels actually have 21 different signals all linked to expressing dominance. If the recipient of these messages fails to submit, then the message is put across more aggressively and may cumulate in a frantic chase, which you are likely to witness if you walk through green spaces at this time of year. It might look hostile, but getting all this social bickering out of the way now means the rest of year should be relatively peaceful.  In fact chases take place about eight times more frequently now (late autumn / early winter) than in June, which is a good thing if you happen to be a mother squirrel requiring all your energy to produce and care for a litter. Of course you can witness some frantic squirrel behaviour at other times of year, such as the mating chases which occur in January and early summer. Also, although the status ranking will have been settled, there still might be the occasional rebellion!

What underlies this social ranking system, in which every squirrel knows its place and the place of its cohabiters, is recognition of neighbours. If an unknown squirrel enters an area, it is met with extreme hostility by the locals, as it has no place in their social structure.

Overlapping territories can lead to some squabbling, particularly at this time of year, but this strategy does mean that if a certain resource becomes bountiful, such as an oak producing acorns, all the squirrels in an area may benefit from it by coming together to feed in the same place. That is, as long as everyone remembers their place and respects the unspoken social code.  Much like sharing mince pies at Christmas in fact!

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