Autumn spectaculars - ruts, nuts and flocks
With a chill creeping into the air and the Met Office predicting the coldest August for 100 years, autumn is fast approaching. But rather than reflect on the loss of warm summer days, think about the exciting spectacles that will be occurring in the natural world. I will be highlighting just some of them for you to look out for.
When wandering through the golden leaves of an autumnal forest, you may be lucky enough to witness rutting deer. Put simply, the rutting period is the time of year when deer mate. During this time, adult males (called stags) are full of testosterone and compete for access to groups of females called harems. The three largest British deer (the red, fallow and sika) all rut in the autumn. The red deer is Britain’s largest land mammal, and like many deer species it tends to begin rutting in September, with activity peaking in October and ending at the end of autumn/beginning of winter.
When two males are competing for females they will first challenge one another by roaring. Generally speaking, the deeper the roar the larger the stag, so a smaller stag may give up a competition if its opponent’s roar is substantially deeper (the smaller stag knows it is unlikely to win the fight).
Dominance can therefore be determined without contact fighting taking place, eliminating the risk of injury to either stag. If neither stag backs down after the roaring match, they then walk parallel to each other, assessing the strength of their opponent. If the conflict is still unresolved, the deer lock antlers and participate in an aggressive shoving match, with each stag trying to gain the advantage by being uphill. This will continue until the weaker stag is finally forced to give up.
Take a look up in autumn and you may see the picturesque sight of swallows huddled together in large numbers on telephone wires and branches. They flock together like this before starting their migration back to South Africa in September and October. Migrating swallows cover 200 miles a day, mainly during daylight, at speeds of 17 to 22 miles per hour. These tiny match-box-sized birds fly an incredible 6000 miles to reach their wintering grounds.
Later in autumn, parts of the sky fill with dark clouds of starlings called murmurations. Hundreds of thousands of starlings join together, swirling and waving as one large, chattering mass. These monstrous groupings offer protection from predators such as peregrine falcons. Starlings also gather to keep warm and nights and exchange information, such as the location of good feedings grounds. They can feed up to 20 miles away from where they roost, but return back to their roost at almost the same time every evening when the daylight fades. In 1949, when starling numbers were greater in London than they are now, so many starlings roosted on the hands of big ben that the clock stopped.
Take a look at the forest floor and watch grey squirrels fiercely hiding their nuts away in the ground as they rush to create a winter food store. This store is incredibly important to a squirrel, as they do not hibernate in the winter months when food on trees is scarce. Squirrels have to be careful when burying their nuts, as they can be overlooked by other squirrels who will then steal them. To prevent would-be thieves from being successful, grey squirrels will spend time simply pretending to bury their nuts to fool each other. This behaviour increases in frequency if a squirrel’s hoard is regularly pilfered.
Grey squirrels also use a technique called scatter hoarding to reduce the amount of burgled nuts. They spread their nuts far and wide, making it harder for other squirrels to find them. In contrast, red squirrels are larder hoarders, storing food in one central larder that it defends aggressively. Since grey squirrels obviously need to find their widely spaced nuts again, you may think they have good memories. In fact, the contrary is true. Tests indicate that squirrels can forget where they bury their nuts within half an hour, and lose around 20% of their nuts (estimates vary). Primarily, it is their good sense of smell that enables them to find their nuts again, however some research says they do use their memory to an extent.
Autumn is a magical and often underrated time of year, full of action, competition and anticipation before the winter draws in. The forests are rich in colour and the fresh wind rushes through the leaves. Deer roar, birds flock and squirrels scamper, whilst many other animals also prepare for the cold winter months. So rather than feel sad when the summer has passed, feel excited about the autumn that lies ahead and get outdoors in your big woolly jumper.
References
Photographs:
Acer japonicum (leaves), Jean-Pol Grandmont, 2007, accessed via Wikimedia Commons
Red deer roaring in mating season 2009 in Denmark, Bill Ebbesen, 2009, accessed via Wikimedia Commons
Hirundo rustica (barn swallow), Hugo.arg, 2007, accessed via Wikimedia Commons
Starlings forming fascinating formations over Tøndermarsken, Tommy Hansen, 2006, accessed via Wikimedia Commons
Eastern Grey Squirrel, KirinX, 2007, accessed via Wikimedia Commons
Discover Wildlife, (2012), Understanding the British deer rut, [online], available at: http://www.discoverwildlife.com/british-wildlife/understand-british-deer-rut accessed 20 August 2014. Jacobs. L. F and Liman. E. R, (1990), Grey squirrels remember the locations of buried nuts, Animal Behaviour, 41:103-110.
National Wildlife Federation, (2008), Baffling the bandits, [online], available at: http://www.nwf.org/news-and-magazines/national-wildlife/animals/archives/2008/science-sleuths-how-squirrels-hide-nuts.aspx accessed 20 August 2014
RSPB, (2014), Starling flocks: a wild spectacle, [online], available at: http://www.rspb.org.uk/wildlife/birdguide/name/s/starling/roosting.aspx accessed 20 August 2014
Telegraph, (2008), Cunning squirrels pretend to bury their food, Nic Fleming, [online], available at: http://www.telegraph.co.uk/science/science-news/3322101/Cunning-squirrels-pretend-to-bury-their-food.html accessed 20 August 2014
Telegraph, (2009), The mathematics of murmurating starlings, Daniel Butler, [online], available at: http://www.telegraph.co.uk/earth/wildlife/4736472/The-mathematics-of-murmurating-starlings.html accessed 20 August 2014
The British Deer Society, (2014), Red deer, [online], available at: http://www.bds.org.uk/red_deer.html Accessed 20 August 2014
Thompson. D. C and Thompson. P. S, (1980), Food habits and caching behaviour of urban grey squirrels, Canadian Journal of Zoology, 58(5):701-710
Wauer. R. H., (1999), Heralds of Spring in Texas, Texas A&M University Press, p.106
