(for Ed Lenz….Welcome Back! We have missed you!)
One week to spring break and it still feels like winter. I am sitting at my writing desk watching a cold front blast across my hillside. The bird feeders are swinging wildly in the wind spilling their black, oil sunflower seeds all over the top of the seed husk pile that has built up on the ground over the winter. I will have to shovel those out later in March and talk to Ed about how to get the grass to grow in again! The four gray squirrels that come to my feeders have done very well this winter. I think that they are fatter now than they were in the fall (100 pounds of shelled corn and all of the spilled sunflower seeds!). I used to try to keep the squirrel s away, but quickly realized that the battle against them could not be won. So, I put a pile of corn on the ground under the feeders every morning and they eat that and some of the spilled seeds and seldom actually climb up into the feeders. They do very little damage and are incredible sources of entertainment for my house-bound cats and, of course, Kozmo who is not amused by them in the least!
Gray squirrels are really not gray at all but are instead a mixture of black, white, and brown. Most hairs on a “gray” squirrel, in fact, are banded with all three colors. White tips generate the “gray” illusion. Within any population of gray squirrels lighter and darker individuals can be found. “White squirrels” or “black squirrels” may be locally favored by natural or human-generated selection forces. The undisturbed North American population of gray squirrels was, according to historical records, predominately made up of “black” individuals probably due to the effectiveness of the black coloration as an aid in hiding from avian predators such as hawks or owls. The black squirrel, however, was very clearly outlined against the light colored sky when humans hunted the squirrels from the forest floor. This human hunting pressure, apparently, favored the mixed, “gray” coloration that even today predominates in most North American populations. One of my feeder squirrels is actually bright orange in color. I don’t have an explanation for that yet.
Gray squirrels do not hibernate but instead rely on their fat reserves and cached mast stores to survive the long, cold winters. They can be seen out in the winter months as long as the temperatures are not too cold (the literature says their lower limit is around 30 degrees F) and as long as it is not raining or snowing. Food forages are calculated risks in which the use of energy (fat) reserves must yield a food “profit” or the squirrel’s vital fat insulation layer will be diminished and the individual will be less likely to survive the winter. My squirrels, though, have been at the feeders almost every day this winter even when it was close to zero degrees and even when it was snowing. The reliability of the food source (endless corn and sunflower seeds!) must make the stress risk more than tolerable!
Crows form a background to my front yard feeders. They typically roost in the trees back behind my across-the-street neighbor’s house and forage freely in her yard. Every once and a while one of them lands in my yard near the feeders, but the scent of dogs and cats and people, and the confines of the fenced in yard must be too much for these cautious birds to tolerate.
Crows are seldom seen alone. In the non-breeding part of the year (fall through the winter) they form large, communal flocks of hundreds to thousands of individuals. Smaller sub-groups of these communal flocks daily forage out across the countryside sometimes traveling as far as thirty miles from a central roosting area. During the breeding season (spring to late summer) the crows form smaller, familial flocks but still forage in small groups daily searching for food. The flocks, especially the very large non-breeding flocks, establish distinct “pre-roosting areas” within which they engage in a variety of energetic vocal and flight communication behaviors (often to the dismay of humans in the immediate area!) before retiring to their true “roosting areas”. Communication between individuals in the foraging groups and within the larger roosting flocks is a very important aspect of crow biology. The remarkable and extensively documented intelligence of crows (their ability to solve food-gathering problems, to learn to mimic all sorts of vocalizations and to employ a variety of complex strategies to gather food etc) is thought to be a direct extension of their evolutionary success as a social, highly efficiently communicating species. Crows have longer rearing and nurturing periods than other bird species. These “learning periods” are even longer than many of those observed in a number of mammal species. These nurturing periods can last up to a year and a half and enable the parental generation to pass along cultural information and extensive amounts of very functional survival information to their offspring.
So, I am sitting here waiting for Spring. The fat squirrels and the hundreds of feeder birds and the dozens of background crows are all waiting, too, but they are keeping busy with the fundamentals of finding food and surviving. Maybe I’ll grab a sandwich while I’m watching!
In a week I will be flying off into the summer of the equatorial tropics! The Penn State New Kensington trip to Ecuador and the Galapagos will fill up most of the days of our Spring Break. Watch the campus homepage for news and e-postings from the group! A slide show and more will be coming!