At this time of the year the Rougemont squirrels take full advantage of the rich autumn harvest of energy rich acorns, beech mast and chestnuts. There is no time quite like the present for stocking up on vital food stores in preparation for the lean times ahead.
I stood on the footpath just beyond the impressive Monterey Pine which grows in the grounds of Rougemont Castle behind the city library. Using keen sense of smell, several squirrels were foraging amongst wind strewn leaves, searching between the damp blades of grass for fallen nuts and seeds.
My eyes were drawn towards one particular individual as he negotiated his way down the steep wooded slope which lies below the castle wall, acorn held tightly between teeth. Making a brief stop at the base of the slope in the shadows of the yellow leafed Tulip Tree, he reared up on his hind legs in familiar squirrel posture surveying the surrounding area before cautiously stepping forwards into open space.
Another short hesitation, another look around and then he was on his purposeful way, quickly bounding across the grass with bushy tail trailing, to a position a few metres from the foot of the large smooth barked beech which stands proudly nearby. With back arched and strong action from the shoulders, using fore feet and claws, a furious bout of digging then followed.
The acorn was deposited carefully in the resulting hole and then speedily concealed with a covering of soil and leaves. The cache had been made in about 20 seconds and as soon as the job had been completed, this industrious fellow was on his way once again, back up the incline in the direction of the Evergreen Oaks.
Caching behaviour is extremely important for the grey squirrel (Sciurus carolinensis). This is an animal which does not hibernate and it must be able to source daily food supplies throughout the winter. Time spent in nut caching is time very well spent indeed as it ensures a supply of energy rich food needed for when the going gets tough. Cache benefits you might say!
Within its home range, a squirrel may cache thousands of nuts. However, for all this effort to be worthwhile an individual, when requiring future meals, must be able to relocate these caches. Research suggests that squirrels use spatial memory to achieve this. They store information about landmarks and features close to the cache sites. These serve as sign posts 'directing' the squirrel back to the cache area when it needs to make a return visit.
Once in that area, the squirrel uses its sense of smell to pinpoint the precise cache location. Different colours and odours can also be memorised.
Caches are spread out within a limited area around the food source and by making a mental map, a squirrel can determine the position of one cache in relation to others nearby.
Grey squirrels are remarkable animals. They can discriminate between acorn varieties which are long lasting, worthy of caching and those which germinate soon after they have fallen from the tree. Rather than being cached, the latter are consumed.
Squirrels are not averse to stealing nuts cached by other individuals, particularly when food is in short supply. They observe each other, looking out for caching activity. Counter measures have to be taken!
Sometimes a squirrel will simply carry food items further from the source or it may decide to dig up old nuts and reposition them. On occasions it will pretend to cache a nut knowing that other individuals might be watching. How crafty is that?
Grey squirrels were first introduced to Britain in 1876. There followed further introductions to a small number of locations around the country, including Rougemont Gardens in 1915. Perhaps the individual I had been observing is a descendent of those original Rougemont specimens. Now that's a thought.
