Photo by D. Sillman
My family has a long history of providing food for birds and, often unintentionally, other types of wildlife, too. My father had a dozen bird feeders around his house in Arkansas and spent many enjoyable years of his retirement feeding and watching the birds. He also had an ongoing war of wits and weapons with the army of grey squirrels that descended onto his feeders every day. He bought “squirrel-proof” birdfeeders and even designed a few squirrel-blocking devices of his own (he was a very talented engineer), but none of them were successful. If the squirrels could not bypass or evade the blockages, they simply tore them apart with their sharp, relentless teeth. The squirrels even got used to my father’s noise makers and pellet guns and effectively adapted to the occasional feeding disturbances by scattering up into the surrounding trees until the prevailing Ozark quiet returned.
At first, I continued my father’s war on squirrels when I finally matured enough to have a yard and spot for birdfeeders, but finally I surrendered to them. The more I made the feeders “squirrel-proof” the more the squirrels were likely to destroy the feeders, and my bird feeding budget was far too modest to keep up with constant “hardware” replacement!
So, I put seed on the ground and even started spreading shelled corn and, in the winter, peanuts around for the squirrels. I also started admiring the incredible acrobatics that the squirrels employed daily just to get some mouthfuls of sunflower seeds! Hanging by one foot from the bottom of feeder, doing free-hanging sit-ups to reach the seeds must be a hard way to eat, indeed! The amazing thing is that once I accepted and facilitated the squirrels’ feeding, the wonton destruction of my feeders stopped and an acceptable (and visually entertaining) staus quo was established.
Photo by D.Dewhurst (USFWS)
My son, Joe, was home a few weeks ago for a summer visit. He lives in Seattle now and is doing all sorts of things about which I am extremely proud (I’d list them here, but then I would run out of space for the rest of the blog posting!). Anyway, Joe was watching our front feeders one morning and noticed that there were only grey squirrels gorging on the corn and sunflower seeds. He remembered that when he was younger there was a mix of grey and red squirrels at out feeders, and that we often had problems with the red squirrels getting into our attic and chewing through window screens to get to the stash of birdseed on the porch. Where, he wanted to know, did all of the red squirrels go?
Sometimes you need some distance from a place to see its changes. Joe’s five summers away from home gave him just the right perspective, and he was right about the red squirrels. There used to be a rotating pattern of grey and red squirrels at the feeders. Now the greys were seemingly there all day! Watching closely, though, we did see a single red squirrel at the feeder in the later afternoon.
Where did the red squirrels go?
They are also asking this question in Great Britain, but we have to be careful about linking the two discussions. It is another case of “common names” and “scientific names” that we talked about in a previous posting (“True Names”). The “red” squirrel in Great Britain is Sciurus vulgaris. The North American “red” squirrel is Tamasciurus hudsonens. Very different animals!
In Great Britain the alarming decline in their red squirrels is due to two main factors: loss of coniferous forests (due to logging, land clearing, and climate change), and the introduction (in 1876) of the North American grey squirrel (Sciurus carolinesis). The loss of coniferous forests removes the principle food source of the red squirrel, the seed-rich cones of pine and spruce trees. The small red squirrel is well adapted to finding and gathering these cones and seeds and is able to out-compete most other seed eaters in these ecosystems. Red squirrels can live in deciduous forests, too, and are able to eat “mast” sources like acorns. They do not, however, digest these acorns very efficiently and, thus, have less food energy to sustain their activities and their rates of reproduction.
The introduction of the North American eastern grey squirrel to Britain was intentional but not historically clearly explained. The excitement of having an “exotic” squirrel species in the woods around Henbury Park, Cheshire is a likely explanation, but these grey squirrels responded as exotic invasive often do by multiplying and spreading all through their new habitats. Grey squirrels are now found in most areas of Great Britain. The grey squirrel does not directly interfere with or harm the red squirrels (in fact there are more recorded examples of red squirrels chasing off larger (although usually immature) grey squirrels from feeding areas than vice-versa). The grey squirrel does, however, consume a great deal of the seed and mast resources in a deciduous forest ecosystem and thus leaves less and less food for the less efficient red squirrel. So, as deciduous forests increased in Great Britain, red squirrels found it harder and harder to “make a living,” and their numbers declined. Grey squirrels also carry a virus that causes the disease called “squirrel pox.” The British red squirrels were not as resistant to this virus as the invasive greys, so the virus took its toll on the red squirrel numbers.
But, this isn’t exactly what has happened back here in Apollo, Pennsylvania!
The North American red squirrel like the British red squirrel does favor coniferous forests and does thrive when cones and seeds are available. The decline in coniferous forests in North America, though, has not been as extensive as it has been in Great Britain (although the long term impacts of climate change are casting a foreboding shadow over these ecosystems!), and the overall numbers of red squirrels in North America does not seem to be declining. North American red squirrels are moving into deciduous forest habitats but, as has been observed in Great Britain, they end up with less energy available for life processes are compete poorly against the more mast-adapted grey squirrels. Maybe most significantly, North American red squirrels are not as vulnerable to squirrel pox as the British red squirrels.
So what happened in Apollo? There is a local decline in red squirrels, but this decrease is not a part of a continental decline in the species’ numbers. What has happened here over the past decade?
As I discussed in a previous post, nine years ago a series of thunderstorms blew across our hill here in Apollo and knocked down eight (of the original twelve), fifty year old spruce trees (a mix of Norway and Blue spruces). My theory is that the removal of these cone and seed producing trees decreased the carrying capacity of our property for red squirrels. So, instead of having dozens of red squirrels running around (and chewing their way into the attic and porch) we now have just a few red squirrels that feed on the much smaller number of cone producing spruces (and whatever birdseed that they can glean).
The other side of Joe’s observation (that the grey squirrels are so abundant) may be due to the growth of the new oaks trees where the spruces once stood. These trees, as I have also previously mentioned, are starting to produce acorns and are, thus, increasing the food resource base for the acorn-loving grey squirrels. Another possibility to explain the surge in the numbers of the grey squirrels is the recognized détente between them and me. All of those scoops of sunflower seeds, piles of shelled corn, and bags of peanuts must have an impact on the grey squirrel biomass!