Oct 192017
 

Bird numbers and diversity at feeders at feeders depends on wild seed abundance

If you’ve been paying attention to coniferous trees this fall, you’ve probably noticed the abundance of cones on many species. Cedars and spruce, for example, have produced an especially heavy crop. The quantity of seed on sugar maples, too, is of epic proportions, most likely in response to last summer’s drought. In fact, the maples put so much energy into manufacturing seeds that the leaves on many trees never grew to their normal size.

The relative abundance of seed has a ripple effect on other species, as well. For instance, it goes a long way to telling us what birds are most likely to keep us company in the coming months. Anyone who feeds or watches birds knows that the relative abundance and diversity of species varies widely from one winter to the next. Last year, for example, thousands of robins overwintered in the Kawarthas. This was largely due to an abundance of wild grape. American goldfinches and purple finches were also very common. Other species, such as pine siskins, were almost completely absent.

The fluctuation in winter bird abundance is most noticeable in a group known as winter or northern finches. The term is used to describe highly nomadic species like redpolls, siskins, purple finches and pine grosbeaks, all of which belong to the Fringillidae family. Some winters, they don’t show up at all, while other years there are so many that they empty your feeder in only a day or two.

Northern finches move south – or sometimes east or west – in late fall when there is a shortage of seeds in their breeding range, which extends across Canada’s boreal forest. Seeds come in many forms. These include berries (e.g., mountain-ash), catkins (e.g., birch) and cones (e.g., spruce). In the case of cones, the seeds are located under the scales. The key seeds affecting finch movements are those of white and yellow birches, alders, American mountain-ashes, pines and spruces. If seed crops are good in the boreal forest, the birds usually stay put. If food is lacking, they will sometimes fly thousands of kilometres to find it. Whether they actually choose to spend the winter in central Ontario and the Kawarthas depends mainly on the abundance of seed crops here.

Since the fall of 1999, Ron Pittaway of the Ontario Field Ornithologists has prepared an annual forecast of what winter finch species are most likely to make an appearance in southern and central Ontario during the coming fall and winter. The forecast is based on information he collects on the relative abundance of seed crops in the boreal forest. According to Pittaway, cone crops across northeastern North America are of bumper proportions this year – maybe the best in a decade or more. Given the amount of food available, this should be a banner winter to see cone-loving species such as pine siskins and both white-winged and red crossbills. The big question, however, is whether these birds will concentrate in only some areas or be spread out across the entire northeast.

Finch forecasts

1. Pine Siskins – Siskins should be common in the Kawarthas this winter, drawn here primarily by the abundant cone crops on spruce. They will almost certainly turn up at nyger seed feeders, as well.

2. Common Redpoll – Redpolls, too, are likely to put in an appearance. The birch and alder seed crops on which they depend are below average in northern Ontario, so they won’t be hanging around. However, this southbound movement may be slowed or stopped as soon as they discover adequate food supplies. If redpolls do make it to the Kawarthas, good local birch seed crops and an abundance of weedy fields should keep them here. You can also expect them at your nyger seed feeder. If a flock of redpolls graces your backyard, watch for small numbers of hoary redpolls. They tend to be larger, paler and smaller-billed than common redpolls.

3. Crossbills – Thanks to the crossed tips of the upper and lower mandibles of their bill,   crossbills are able to specialize in removing seeds from beneath the scales of conifer cones. Red crossbills prefer pine cones, while white-winged crossbills are attracted mostly to spruce, tamarack and hemlock. There should be a good showing of red crossbills in central Ontario in the coming weeks and months. In fact, many will probably take time to breed, despite the snow and cold. Both species of crossbills are able to nest at any time of the year if food is abundant. Watch for streaked juvenile birds.

Red crossbills are of particular interest to scientists who study evolution. Research suggests that there are nine or ten discrete populations, each of which specializes in a different conifer species. They do not interbreed and may represent different species. Careful examination shows differences in body size and in the length of the bill tip (degree of “crossing”). Most types are impossible to identify, however, without analyzing recordings of their flight calls. Matt Young, a researcher at the Cornell Lab of Ornithology in Ithaca, New York, is studying red crossbills and needs your help. He is asking people to use their smartphone to record the birds’ flight calls and to send him the recordings at may6@cornell.edu He will then identify which of the populations the birds belong to and let you know.

White-winged crossbills move east and west like a pendulum across North America, searching for bumper cone crops. Large numbers have already arrived in parts of the northeast, where they’ve been gorging on spruce seeds. There’s a good possibility that they will also turn up in the Kawarthas, too, and probably right here in Peterborough. Watch and listen for their loud trilling songs given from tree tops and during circular, slow-flapping display flights. Algonquin Park, however, is usually the best place to see these birds. Both red and white-winged are often observed right on Highway 60, where they glean grit and salt from winter road maintenance operations. Unfortunately, crossbills rarely come to feeders.

4. Pine Grosbeak – Most pine grosbeaks will probably stay put this winter, since the mountain-ash berry crop is abundant across the north. A few might get south to Algonquin Park, but they are unlikely to turn up in the Kawarthas. When they do make an incursion into central Ontario, they usually found feeding on European mountain-ash and ornamental crabapples. Considered the most beautiful of the boreal finches, pine grosbeaks can be surprisingly tame.

5. Evening Grosbeak – Most evening grosbeaks are expected to remain in the north this winter. However, you can usually see grosbeaks by checking out the feeders at the Visitor Centre in Algonquin Park. In 2016, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) declared the evening grosbeak as a species of Special Concern due to worrisome population declines.

6. Purple finch – Most purple finches will stay north this winter, thanks to the heavy seed crops on conifers and mountain-ashes. They usually appear at my feeder in early fall, but this year I’ve haven’t seen any. An easy way to tell purple finches from look-alike house finches is by checking the tip of the tail; the former has a distinctly notched or slightly forked tail, whereas the house finch’s tail is squared off. Both species prefer black oil sunflower seeds at feeders.

Non-finch species

1. Blue Jay – Thanks to a good crop of acorns, beechnuts and hazelnuts, large numbers of blue jays will probably remain in the Kawarthas this fall and winter. I am already noticing above-average numbers.

2. Red-breasted nuthatch: Like many of the finches, this species depends primarily on conifer seeds. Pittaway is therefore predicting large numbers in central Ontario this winter. This was certainly the case on Thanksgiving weekend at Big Gull Lake, south of Bon Echo Provincial Park. Red-breasted nuthatches were by far the most common bird.

3. Bohemian waxwing: Most bohemians should stay in the north, because of the large berry crop on American mountain-ash. That being said, we almost always see at least a few flocks of this species in the Kawarthas every winter. This may be partly due to the local abundance of European buckthorn, a non-native shrub that produces a large berry crop every year. Bohemian waxwings are also attracted to European mountain-ash and ornamental crabapples.

4. American robins:  Although not part of Pittaway’s forecast, I suspect that robin numbers will be low this winter, given the poor crop of wild grape. Last year, thousands of robins overwintered here and gorged themselves primarily on abundant wild grapes.

The best way to stay on top of bird movements across Ontario is to subscribe to Ontbirds. You will receive a daily digest of sightings. Sign up at ontbirds.ca/mailman/listinfo/birdalert_ontbirds.ca To follow what’s happening locally, I recommend using eBird. When you go to the website, click on “Explore Data” and then “Explore a Region”. Type in “Peterborough, Ontario”. Choose “Current Year” and then click on “Set”. You will see an up-to-date list of all species seen in the area. By clicking on “Species Name”, the birds will appear in the same order as in your field guide. By clicking on the date, you will see where the bird was seen, along with other species observed at the same location.

Project FeederWatch

If you feed birds, you can support research and conservation by taking part in Project FeederWatch. Simply count the kinds and numbers of birds at your feeder, and then submit your observations. This information helps scientists study winter bird populations. To register, go to birdscanada.org/volunteer/pfw/ or call Bird Studies Canada at 1-888-448-2473.