When I was young I was taught nature exists in a state of equilibrium — that predators keep prey in check, and that plants and animals live in balance. As time passed I came to learn that nothing could be farther from the truth. This winter is providing great examples of just how imbalanced nature really is.
Over the past three weeks, the Christmas Bird Counts in which I participated took me from Kingston to Arnprior, Algonquin Park and, finally, Dunrobin. On these events I got a first-hand picture of the distribution of birds and other animals in eastern Ontario. Two themes became clear: red squirrels and finches (with one exception) were scarce while American robins and other fruit-eating birds were present in surprising numbers.
In some winters, finches such as white-winged crossbills are so abundant that it‘s hard to hear other birds after the sun rises. This winter, apart from the occasional twitter of American goldfinches, dawn arrives in virtually silence. In some years the chattering of red squirrels greets you in every coniferous woods; this year even their tracks in snow are near absent.
The reason for this is clear — coniferous trees have virtually no cones. Conifer seeds are the main food not only of crossbills and red-breasted nuthatches (also scarce this winter) but also of red squirrels. Last fall I watched a red squirrel harvesting jack pine cones, which are so hard they require the heat of fire to release their seeds. By now that squirrel has likely lost a lot of weight or needs dental work; that is, of course, if it is still alive.
On the other end of the scale, apple and other fruit-bearing trees and vines such as wild grape are laden with fruit. This bounty was behind a record number of American robins tallied on the Ottawa and Pakenham-Arnprior counts. The crop was also likely responsible for Eastern bluebirds lingering; the one near Pakenham was the first recorded on that area’s count while the two observed near Dunrobin constituted that count’s second record. The abundance of fruit was undoubtedly why a hermit thrush was encountered in Galetta, and Northern flickers were seen on several counts. Unfortunately, the one in Pakenham, which would have been a new species for the Pakenham-Arnprior Count, failed to show on Boxing Day but was seen during “Count Week,” the three days on either side of the count.
How does this relate to the balance of nature? Well, if fruit and cones were produced in the same volume every year, seed-eaters would be present in the same numbers every year, and they would destroy all of the seeds, leaving none for regeneration. But low production in successive years causes the populations of seed-eating animals like red squirrels and deer mice to crash. Then, when a massive crop is produced, the few animals present can’t possibly devour all of the seeds, ensuring regeneration.
The low years not only affect seed-eaters but also the animals that eat them. Thus, like fruit and cone numbers, animal populations go through roller-coaster rides, creating ebbs and tides that ripple all through the ecosystem.
This imbalance in nature makes each year different. It also makes each Christmas bird count fresh and exciting!
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