What Animal Keeps Putting Rocks On My Roof
As with about any species, there are some facets of behaviour that are more difficult to explain than others; squirrels are no exception. 3 behaviours in particular warrant further attention: caching of non-food objects, typically stones; grit bathing; and a particularly curious behaviour where a squirrel will sit up loftier for hours on cease without moving that I've chosen "sitting high".
Rock caching
A great many species of mammal are known to hibernate surplus food for later retrieval, a procedure known as caching (pronounced "cashing", from the French cacher, "to hide") and squirrels are amid some of the most adept cachers known to science, even going then far as organising their larders to help them call back what's stored where. There are, still, a few intriguing reports of squirrels taking inedible objects and caching them.
The first time I came across this behaviour was in an account from New year's Day 2005, when Maria Salmon contacted veteran squirrel biologist John Gurnell about some foreign behaviour she had seen from a Grey squirrel visiting her garden. The squirrel had been stealing pebbles, each nigh the size of a walnut (i.e. approx. 5 x three.5cm / 2 x 1.five in.), every day for weeks—to the indicate where Ms. Salmon needed to buy some more. This curious behaviour continued until at least the cease of February and plain the squirrel, i of several visiting the property, would come up into the garden and make straight for the pebbles, ignoring the nutrient put out, and carry ane off somewhere. Information technology was never established where the stones were being taken (the squirrel didn't always leave in the same direction) or what was happening to them.
In Baronial 2010, a user posted to the online RSPB Community forum recounting like behaviour; a squirrel was taking gravel and pebbles from their garden "ordinarily after licking it all over". When larger pebbles were added, the squirrel shifted its attention to these and it would typically choice up four or v before information technology settled on ane to accept, suggesting at that place was a specific trait the squirrel was seeking. In this private's case, still, while some stones were buried, others were left on debate posts, on the summer house roof or nether the summer house. Subsequently, I've come up across reports online of similar stone-burying behaviour from Greys both here, in the USA (Maine and California) and Canada (Peterborough, Ontario). In some cases the stones were licked commencement, but in all cases the stones were removed and either buried or assumed to have been buried.
In April 2011, a lady contacted me describing how:
"A cheeky greyness squirrel runs up to the house from the bottom of the garden, sniffs the ground for a few seconds then carefully selects a rather big piece of gravel (c. 2cm in length, smoothen, more of a small pebble), puts it in his mouth, finds another the aforementioned size and puts that in his rima oris besides, then runs off down to the conifers at the bottom of the garden!!"
The squirrel was doing this near of the solar day and had removed quite a few stones.
In December 2018, Vicky Harrison got in touch to tell me most Greys visiting her property that "consistently have small stones from my garden and bury them, usually next door". Vicky first noticed this behaviour in the winter of 2017, and it appeared to exist just a single individual that was collecting pebbles who was "very item about the size (acorn) and shape (smoothen) of the selected stones". By the post-obit autumn 4 of the five or six visiting squirrels were doing it and, in some cases, jagged stones were taken. The stones were taken throughout the twenty-four hours and mostly buried in a neighbouring garden, although Vicky institute several in her blossom pots.
Between August and November 2020, I received eleven reports of "stone stealing" behaviour; seven were from the UK (including Sussex, Oxfordshire, County Durham and Edinburgh) and 3 from North America, ane in Minnesota and two in Canada. All the descriptions have the same bones elements in common: one or 2 squirrels carefully select stone, rotate them in their forepaws often while licking them and so take them abroad. In several of the videos I have been sent, the squirrel tin conspicuously be seen burial the rock before returning for another, while in others the squirrel disappears. Fifty-fifty in the reports that don't run across what happens to the stones, the speed with which the squirrel returns suggests they're beingness cached. The stones vary in size and shape from acorn-sized to walnut or slightly larger ("boiled egg cut in half" as one observer described it to me). In just one instance and then far has a colour preference been evident. Jane Hankinson told me:
"The stones are about the size of an acorn and interestingly always a night dark-brown colour, fifty-fifty though I have a mixed colour pebble surface area in the garden."
Thus far, all but one study I have plant involve Grey squirrels and I have even so to come beyond an example of the behaviour in European Reds, although this may simply reflect the Grey's more than cosmopolitan distribution and propensity for visiting gardens. This behaviour is not, notwithstanding, exclusive to Greys and in Baronial 2020 Keith Guise, from New Brunswick on Canada's east coast, contacted me to describe repetitive stone caching behaviour by an American Red squirrel (Tamiasciurus hudsonicus) visiting his isolated mountain garden. Keith described how the squirrel selects smooth rounded greyness stones about ii.v-3.5cm (i-1.5 in.) in bore and either disappears off into the woods with them or leaves them around the garden in the plant pots. This happens throughout the summer and Keith told me:
"... we see it nearly four or v times per twenty-four hours but there could be more; it goes to great trouble to choose the one it wants, picking them up putting them in its mouth, turning the stone around until it has the "best" i; ever heads off on the same route down our mountain ..."
This is certainly intriguing behaviour and not something I, or many squirrel biologists based on my research, have e'er observed personally.
I have been unable to find whatever reference to this in the literature and Max Planck squirrel biologist Pizza Ka Yee told me that, despite being curious well-nigh it, she has never seen the behaviour. Lucia Jacobs, a neuropsychology professor at the University of California, Berkeley, who has spent much of her bookish career study caching behaviour in Greys, has observed the caching of non-food items only very rarely—in ane example a squirrel stole their experimental cue, which was shaped like an ear of corn, and cached information technology. regardless, all accounts describe a patient deliberation well-nigh the selection of the stones and the regularity with which it is carried out, suggesting some purpose the squirrel was invested in.
Unfortunately, there are even so a keen many unknowns about this behaviour. We don't know if information technology is sex- or historic period-specific, for example, although several of the reports I've received have suggested yearlings. We also don't know whether the stones are always retrieved or relocated, as regular caches are. Nosotros do know that squirrels are very proficient when it comes to selecting seeds for caching and take a adept sense of odor, which might suggest they're unlikely to have mistaken the pebbles for food. Indeed, Alan Walker in Shropshire told me that the squirrel taking stones from his garden dropped the rock it was carrying when took the walnut he was offer instead. Similarly, in Vicky'southward description, squirrels visiting beyond years exhibited the behaviour, implying they were presumably feeding themselves in between these bouts of pebble caching. Several other readers who have provided their observations feed squirrels in their garden and watch them cache both stones and nuts during the aforementioned observation period.
Thus far, at that place announced to be three theories offer an explanation for this behaviour. 1 suggests, based on finding stones in the lining of a squirrel's drey, that they may exist used every bit ballast or even 'radiators', although, in my view, this is an unlikely explanation and information technology seems probable that the stones were incidental inclusions.
A second hypothesis, provided past Natural Heritage Data Middle zoologist Don Sutherland, considers that it may be an attempt to disguise food caches and reduce cache-pilfering by other squirrels. Off-hand, information technology seems this could piece of work in ii ways: information technology may serve to 'dilute' the caches such that any potential thief would potentially uncover a stone for their trouble rather than a nut; or a stone could be placed on elevation of a food particular to fool a potential pilferer. I've not come across testify to back up either of these in the electric current observations, just both seem plausible, although when Fiona Turner dug up one of the caches in her Oxfordshire garden, she found merely the stone.
Thirdly, and in what is probably a logical extension of the same, Professor Jacobs points to enquiry by scientists at the Konrad Lorenz Forschungsstelle, part of the University of Vienna's Faculty of Life Sciences, which institute ravens openly cached minor toys (i.e. low value items) they were given when in the presence of competitors, but hid food (high value) more diligently. The researchers suspect that the ravens practise this to practice being pilfered from, and it's possible squirrels do something like with the stones they have.
Taking the thought of enshroud pilfering exercise and cache dilution a little further, it is tempting to speculate that stones may exist used either to help evaluate a new storage site, keep a competitor busy and/or dissuade them. To the first point, we know some squirrel species appear to organise their caches to help them recall what's stashed where and that retentiveness and eyesight seem to play the nigh significant signal in cache retrieval. If Greys operate a similar grouping tactic, they might exist able to use stones to "examination out" caching locations at relatively low price; they're losing stones, not food. If they coffin stones around the identify and they all remain in situ information technology's probably a skillful hiding spot. If the stones get dug up or moved, mayhap this is a place all-time avoided. Similarly, Squirrel A, having watched Squirrel B busy making caches in an area, may spend its time scouring this spot (and finding only stones) rather looking elsewhere where the food is hidden. If Squirrel A just ever finds stones upon pilfering Squirrel B'south caches, could it make up one's mind not to carp going after this private's caches in future?
A terminal thought, and one I confess shows limited promise relative to the above, is that the squirrels may be using these stones as a mineral source. Most reports of this behaviour describe the squirrel licking the rock before taking it away and while I believe some observations are really just the squirrel rotating a stone in its oral fissure trying to notice a secure grip, several do give the stiff impression that the squirrel is genuinely licking it. In one case, Richard Stallard described licking behaviour in squirrels taking stones from under the bird feeder in his Sussex garden and, when I mentioned a possible mineral source, noted that he'd been distributing salt in his garden to try and reduce the slug population and that, living on the coast, they get salt deposited on the house and garden from sea spray. Similarly, Nikki Wyrill from Dorset observed a squirrel very selectively removing stones from her garden and suggested to me "I too live on the coast in a very windy expanse - then perhaps the theory of salt deposits on the stones may exist truthful".
We know squirrels volition use mineral licks and that mineral deficiencies, particularly low calcium levels, have been linked with bark-stripping behaviour. In the early 1980s, Lawrie Tee tried, albeit unsuccessfully, to reduce bawl-stripping past providing a mineral lick for Grey squirrels, while Alexander Panichev and colleagues recorded Crimson squirrels visiting "kudurs" (mineral rich soil outcrops that are eaten by animals) in Russia's Sikhote-Alinsky Biospheric Reserve. More recently, reader Jon Southwood got in touch to describe a Grey squirrel he observed and photographed licking at a stone column at Fountains Abbey in Yorkshire - the squirrel seemed very determined and ignored Jon taking photos. Finally, Fiona Turner contacted me when she observed what appeared to her to be a youngster taking stones from her garden. What fabricated Fiona's account specially intriguing is that this behaviour only started when they replaced the balmullo gravel aggregate with Douglas Muir quartz. Photos and descriptions from other readers propose quartz/quartz-like stones are often chosen. If mineral deficiency is a commuter backside this curious behaviour, this may business relationship for the squirrels existence so discerning in their selection of stones.
And then, at this indicate, we can't say with whatsoever certainty why squirrels take and bury stones. In my view, the idea that they're using it equally a pseudo/dummy/test cache seems to brand the most sense, but even this theory is not without its holes, and then to speak. The squirrels aren't plainly existence watched, and brand no endeavor to "fake enshroud" the stones every bit they do with food when they think somone'due south looking. This behaviour also seems all encompassing; a single squirrel will bury dozens, perhaps hundreds, of stones over a season, which presumably impacts its power to enshroud nutrient to encounter information technology through the winter. Equally such, this may really be an abberant behaviour. Unfortunately, no stone caches have withal been methodically studied, so we don't know whether they normally contain food too, although some annecdotal reports propose some practice, or whether the owner ever returns. I would exist very interested to hear from readers who have observed this behaviour or accept theories as to its purpose.
Grit bathing
Animals, particularly birds, rolling around in dirt or sand is not an uncommon sight. This is a phenomenon we refer to as a maintenance behaviour, because we think it helps rid the bather of parasites, while also probably helping soak up excess oils in fur and feathers to go on them and the skin in adept status. For mammals, this is largely speculative, merely in the case of some birds, chickens in particular, we know that they develop skin weather if denied admission to a dust bath, suggesting it is essential for their wellbeing.
Interestingly, despite this being a behaviour often recorded in ground squirrels, dust bathing appears less commonly witnessed among tree squirrels and I can detect no reference to it in the literature. I accept, notwithstanding, come across a handful of reports online and from readers describing Greys rubbing themselves on the ground, in wood fragments of decomposing logs and fifty-fifty in bloom pots, engaging in what appears to exist grit bathing. (I would be interested to hear from anyone who has observed like behaviour in Carmine squirrels.) These accounts all take a couple of elements in common: they ever occur in dry dirt/wood—I'm not enlightened of any examples of wallowing behaviour in squirrels—and are typically punctuated by bouts of grooming and scratching.
It is besides worth noting that some of the same body and chin rubbing that is associated with scent marking is ofttimes observed during dust bathing; this may exist coincidental, or it may imply that dust baths accept a role in territorial maintenance as well as pelage maintenance. Certainly, this seems to be the case in some rodents and in his Ph.D. on Belding's ground squirrel (Urocitellus beldingi) ecology, issued in 1972, University of Arizona biologist Larry Turner described how these rodents grit bathed as part of their grooming regime too as during aggressive encounters with intruders. Turner noted that squirrels often rubbed their upper backs while bathing, plainly depositing scent from the dorsal pare glands that lie in the shoulder region:
"Secretions from this gland leave an odor in dust bathing areas, and at the same time, the dust absorbs excessive secretions which might mat the fur. Thus grit baths may serve the dual function of scent marking an surface area and personal cleanliness."
As far as I know, no studies have thus far been conducted on bathing sites of grayness squirrels.
Sitting upward high
Over the bound of 2020, I received four accounts of squirrels patently taking prolonged refuge up high, and in December 2021 a similar observation was posted to a Facebook group. Two cases involved squirrels sitting right at the top of a tree, one atop a telegraph pole, the fourth on the side of a person's house, upwards by the apex, and the almost recent one an developed Grey remained 'frozen' in the same location in a tree in the observer'south front garden in Shropshire. In all these cases, the beast remained there for several hours and in a couple of instances for more 24 hours. In the example given to me by Claire Moylan in April 2020, for example, the squirrel sat motionless in the top of a tree at the bottom of her garden for just over 24 hours, ignoring food she left at the bottom for it, earlier information technology simply climbed down and ran off. During this fourth dimension, the squirrel sat upright (non obviously sunbathing) and didn't vocalise while Claire was watching. The following month, Bob Cole described a like, but slightly different, behaviour in a Grey outside his house:
"We accept a greyness squirrel which for the past iv days has been sitting on top of a telegraph pole in the garden for several hours each day. The kickoff day there was lots of 'barking' and alarm calls, but non and then much since."
In only one case was this aerial freezing behaviour seen to follow a traumatic encounter. Surrey-based writer and designer Siobhan O'Neill described an incident in which i of the squirrel frequenting her garden was caught by a neighbour's cat:
"... but let her go as I went charging out later them. She sat terrified in a tree at the terminate of our garden for hours. We kept checking and put water and nuts on the roof of our nearby shed for her but eventually she recovered and left."
Taken together, these accounts tentatively suggest that, following a distressing event, a squirrel may seek safety upwards high. At first appraisement, these locations may seem rather exposed, only that may be of do good to the squirrel if its main business is ground predators. The squirrel presumably remains in the location until either it feels safe again, or is driven down by hunger/thirst.
Source: https://www.wildlifeonline.me.uk/animals/article/squirrel-stone-caching-dust-bathing
Posted by: romannottly.blogspot.com
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