Buckthorn berries and Bohemians

Common Buckthorn (Rhamnus cathartica) berries

While out walking the other day I came across a single, lonely buckthorn shrub-tree along one of our fencelines. It stood out from the other woody vegetation because it was the only one in the row that bore any berries. We have so few berry-bearing bushes on our property, I went up for a closer look and some photos.

Buckthorn isn’t native to North America; it’s originally from western Eurasia, and was introduced to North America early in the 1800s. Given the right conditions (which includes disturbed land), buckthorn can be very invasive. It leafs out earlier than many of our native plants, giving it a longer growing season, and plants are very hard to kill – like willows, they’ll resprout from roots and stumps. One site I’ve read also suggests that the shallow, spreading root system outcompetes those of other understory plants. I’ve been to a few places where the shrub has spread and established itself over a wide area. Not a lot of fun when you have to walk through it! The name does actually refer to little hawthorn-like thorns that grow at the ends of the stems.

Common Buckthorn (Rhamnus cathartica) berries

When freshly ripe, those berries look like they ought to be tasty, but they’re actually poisonous. A handful of berries will give you abdominal pain and diarrhea; a bowlful can cause serious problems. The amount of poisonous chemical contained within the berries decreases once they’re ripe – probably a strategy the plant evolved to keep animals from eating the berries before they were ready to be dispersed.

This can cause some problems for wildlife in areas where the plant has been introduced. In its native range, berry-eating birds know not to eat the berries before they’re ripe, but birds not familiar with the plant don’t have that knowledge. They may eat the berries while they’re still toxic, and suffer the consequences.** (Edit: Reader Julie of the Rouge River Bird Observatory in Michigan comments that the author may have jumped to conclusions with the article I linked to at the **. Julie’s own research on avian use of non-native fruits has shown no such toxicity of buckthorn berries to birds. Julie knows a thing or two about a thing or two, so I’m inclined to believe her.) However, if the berries make it past ripening and into the fall, they’re an excellent source of winter nutrition for our birds. Clumps of buckthorn are great places to check out when you’re birding in the winter, because more often than not there will be waxwings or robins or bluebirds or other berry-eaters flitting about the shrubs.

Bohemian Waxwings

Many species will feed on buckthorn, but of particular interest to me are Bohemian Waxwings. The winter specialty of Bohemians is mountain-ash, also called rowan (Sorbus americana), which bears bright orange berries. In years that mountain-ash crops in the north are poor, Bohemians will move farther south looking for food. Once they reach southern Ontario the mountain-ash crops might have improved, but their diet can also be supplemented with the berries of the widespread buckthorn (by the time they make it down here, of course, the berries are well past ripe and entering shriveled).

I saw a flock of Bohemians, 40 of them, while I was out this afternoon. I spotted them before I heard them; they were being unusually quiet for waxwings. I had neither my binoculars nor my long lens, but the way they were all clustered at the top of a couple of trees is, from my small amount of experience, typical of the species, as was their completely unconcerned attitude as Raven and I approached to stand a short distance away. A few birds were calling, which confirmed the ID even if I couldn’t see them well. I stood and watched for several minutes before they all began to call and then abruptly departed.

One buckthorn bush isn’t enough to keep them occupied for the winter, nor is our neighbour’s single crabapple tree. Still, I hope they might linger, that I might meet them again.

Bohemian Waxwings

**As per this article. Some websites are very anti-buckthorn, others are pro-buckthorn, at least in terms of its benefit to wildlife.

Hiking the Rouge

Rouge Valley

Today was Family Day here in Ontario, a newly-created holiday courtesy of our provincial premiere, who believed that the unbroken stretch between New Year’s Day and Easter was just too long for an employee to reasonably have to suffer through. This was the first year the new holiday has been in effect, and there’s still some kinks to be ironed out. Federal employees such as postal workers and some unionized groups were on the job today because the holiday hasn’t been negotiated into their contracts.

Rouge Valley

Blackburnian had the day off today, however, and I’m basically self-employed at the moment and take whatever days I want off, so we decided this afternoon to take advantage of the mild temperatures and head out to the Rouge Valley, out in the east near the Toronto Zoo. Back when I was in university I had a job for a couple summers inventorying the birds of the Rouge Park. It was very informal, I basically spent the summer hiking around as I pleased, trying to cover everywhere but not following any sort of rigorous protocol. It was a fabulous job, and I have a very fond spot for the Rouge because of my time spent there getting to know it and its birds. Despite this, I’ve rarely been back since then, and I’d never been there in winter.

Rouge Valley

The top photo is an image of the valley, taken from the top of a high bluff overlooking the Rouge River. Blackburnian’s standing at the top of the cliff, to give you a sense of scale. This isn’t a little bluff that you’re going to shimmy down to the water. The Rouge Valley contains two primary rivers, the Rouge and the Little Rouge, which joins it. This is the Little Rouge. Doesn’t look so little here, but the Rouge is a bit wider and deeper. Most of the river is upland forest, but there’s the odd patch of wetland here and there.

Civilization in the distance

The Rouge is a gorgeous, mature woodland through most of the Park’s valleys, and it can be easy to lose yourself among the extensive habitat. However, reminders of the city next door are hard to ignore. On the horizon are apartment buildings and rooftops. The trails run 1.6 km along either side of the river, between two roads. Road noise from the city carries the short distance into the park. People come out here to walk their dogs, and many of the dog owners don’t pick up after their pets.

Signs of people

Or themselves.

Rouge Valley

But the scenery is beautiful. The trails cover a number of different habitats, starting in scrubby meadow at the edge of the woods, passing through a powerline corridor, and then entering into mature upland forest. It’s a mixed deciduous-coniferous forest, with the evergreen component mostly hemlock. The trees here are no western Red Cedars, but put in perspective are pretty impressive themselves.

Hermit Thrush

We didn’t see many birds. Of course, winter birding is like that, very hit-or-miss and sparse even when there’s hits. This guy was the indisputable highlight of the outing. A Hermit Thrush, very out of place in the Toronto snow. Seeing a Hermit in the Toronto area isn’t unusual, per se, but it’s certainly very uncommon. This is the first one I’ve seen around here in the winter. Virtually all Hermits leave the province for the winter, though they don’t go far and may winter in the northeastern states.

Hermit Thrush with Black Cherry berry

This guy had found himself a stash of Black Cherry berries. I didn’t even notice the cherries until I saw him pop one. I watched him eat three or four before a movement I made, possibly shifting my weight or adjusting the camera, startled him and he flew off to a nearby hemlock.

Black cherry fruit

Frozen berries such as these are a large component in many overwintering birds’ diets. Two species of northern birds (Pine Grosbeak and Bohemian Waxwing) will feed pretty much exclusively on frozen berries such as crabapple, chokecherry, buckthorn, hawthorn, etc. There seemed to be a fair bit of Black Cherry in the forest, which should give the Hermit Thrush lots to eat.

Flock of robins

The first group of birds we came across were these robins, perhaps 20 of them. Nearly all robins leave the Toronto area in the winter, too, although in recent years increasingly more will stick around through the winter and feed on frozen berries in the woods as well as urban gardens. Another great reason to plant berry-bearing bushes!

Pished off Black-capped Chickadees

We found a few groups of chickadees foraging in cedar stands along the floodplain of the river. Blackburnian pished at all of them, but these were the only group to respond strongly. They were seriously pished off! You can even see the right one yelling, “dee-dee-dee-dee-dee!” Chickadees drop the “chick-a” from their call when they’re responding to perceived threats or dangers. Some research has suggested the number of “dee”s is correlated with the seriousness of the threat, with more meaning a greater danger.

Red-breasted Nuthatch

This Red-breasted Nuthatch pished in with one of the flocks of chickadees. It was the fourth and final species of the outing. I was thinking as we were leaving that it wasn’t a great diversity or abundance of birds, and would’ve made for a very lacklustre Christmas Bird Count. I loved the haziness of the periphery of this image created by peeking through a gap in the foliage.

We walked nearly 4 km on very uneven, slippery trails (not groomed trails, so they were simply packed down by many feet, and every step you were trying not to slide). It’s the furthest I’ve walked since the fall, I’m pretty sure, and the addition of the trail condition means we’ll probably be feeling achey legs tomorrow! Ah, but it was good to get out.