Winter chill showed up last week – along with sparrows arriving from the arctic tundra. Small migrators, just passing through on their way south, huddled among bare limbs. Fall inspires birds to flock and the skies and trees are crowded with bird society. A few wildflowers are still sending off or dropping their last fruits and all kinds of leaves whirl down and carpet the paths. Now is the time when the negative impact of too many deer and invasive plants becomes readily apparent – so we’ll explore “lovely but lethal” creatures and plants in the park as well.
Birds Flock Together in the Chill Winds
Evidently, wildlife experts have various theories about why birds flock in the autumn. The most common explanation seems to be that it’s protection. More bird eyes and ears can spot predators and find food more easily. In some species, the young flock with adults who know more about food sources than they do. Some experts believe birds learn from other birds about new food sources by hanging out in flocks or rookeries. Migrating is easier in flocks in which individual birds take turns flying in front, thereby decreasing the wind resistance for the birds behind them.
And then there’s the possibility that birds are just more social when they aren’t courting or raising young. American Robins (Turdus migratorius) for instance, are chirping all over the park now in small flocks, often high in the treetops. Many robins spend their whole winter here; we just don’t see them on the lawn because they can’t get to worms, so they eat fruits during the cold season.
Mallards (Anas platyrhynchos) gather in large numbers in the marsh. I saw a flock of over 50 last week floating and flying near the Gunn Road end of the marsh – and heard reports of hundreds near Rochester Road. Here are about half of the ones I saw.
Turkey Vultures (Cathartes aura), often seen in ones or twos over the western Old Field during the summer, were soaring in groups of five or more this week. Our “cleanup crew” with its magnificent 6 ft. wing span will soon be gone, migrating to the southeast to spend the winter.
Lately I’ve learned that flocks of Black-Capped Chickadees (Poecile atricapillus) are good places to look for other small birds who hang out with them when in unfamiliar areas. Their “Chickadee-dee-dee” call ends up being a clue to look for fellow travelers like the sparrows below. The reason? Chickadees are great at sounding alarms that other birds heed. The more “dee’s,” the higher the threat. And as year ’round residents, they probably know the best, closest food sources as well. This Chickadee mustered its impressive balancing skills to take off in the stiff winds this week.
Ever wonder how a bird as small as a Chickadee survives during cold, rainy nights like we had this week or cold snowy ones? Cornell Lab says that these tiny birds can excavate their own individual holes in the rotting wood of snags (standing dead trees) – one bird per hole! I’m glad to hear that, since I know chickadees always face the challenge of eating enough to stay alive in cold weather. They store individual seeds everywhere and then can actually remember where they put thousands of them! Here’s how Cornell says they sort of “clear their hard drives” at this time of year: “Every autumn Black-capped Chickadees allow brain neurons containing old information to die, replacing them with new neurons so they can adapt to changes in their social flocks and environment even with their tiny brains.” Wish I could do some of that!
Cold Weather Sparrows Arrive While Sparrow Visitors Pause and Move On.
This winter, flocks of Tree Sparrows (Spizella arborea) will probably gather beneath your bird feeder as well as mine. These distance travelers have spent the summer raising young on the arctic tundra and this week arrived back at Bear Creek. See this link to their beautiful arctic nests made of ptarmigan feathers. These small birds with their warm brown caps and black dot on a gray chest must love cold weather since they clearly think our winters are comfortably mild.
Other sparrows are still just passing through. The large Fox Sparrow (Passerella iliaca) with gray above its eye and on the nape of its neck is heading for backyards and fields anywhere south of mid-Ohio. This one looks especially red-brown because it was basking in the light of a setting sun.
This is probably the last week that the White-Throated Sparrow will be at Bear Creek. Its yellow “lores” (spots in front of the eyes) are present at the top of the beak, a bit faint in this photo, but it had the classic field marks of a white throat and striped head – when it would emerge for a few seconds from hiding among the branches!
The Hermit Thrush (Catharus guttatus) was here last week, foraging near the Center Pond as the leaves thinned out. With the cold north winds late in the week, it’s probably winging its way to Tennessee and points south, like the human “snow birds.”
Seeding for Spring Continues
Like the tall non-native Common Mullein (Verbascum thapsus) above, many wildflowers have finished seeding for the year, but some are still dispersing seeds in a variety of ways. The native Buttonbush (Cephalanthus occidentalis), that looks like a tiny white sputnik when it flowers, is now drooping in the marshes. (Rest your cursor on double photos like this for captions.)
But it’s been a great help to the native wildlife around it. According to Wikipedia, “Waterfowl and other birds eat the seeds. Wood ducks utilize the plant as nest protection. Deer browse the foliage. Insects and hummingbirds take the nectar, with bees using it to make honey.” That’s what makes many native plants good for a habitat – lots of uses for native wildlife.
Remember the loose sprays of native Water Hemlock (Cicuta maculata) that were in or near every park wetland during the summer? This plant, the most toxic in North America, is now making a delicate, brown fruit with tiny hooks that attach to animal fur – or my cotton sweater as I wade into the plants to get a macro photo. In that way, they spread their seeds for next spring.
Native Gray Dogwood (Cornus foemina) has fed lots of birds with its white berry-like “drupes” this fall and now leaves behind a lovely red fringe at the edge of the marsh in the center of the park.
Common Milkweed (Asclepias syriaca) pods are drying and mature seeds are now being released to the wind. If you see seed on the path or anywhere they can’t sprout, pick them up and send them flying! The resident and migrating Monarch Butterflies (Danaus plexippus) that feed on them next summer will thank you.
By the Way..
One Tough Dragonfly!
I was astonished on Friday, after the heavy, cold rain and high winds, to still see another Yellow-legged Autumn Dragonfly (Sympetrum vicinum) calmly sitting on the railing at the Playground Pond. On Sunday a week ago, I’d seen the one in the photo below on a matching red leaf at Seven Ponds and thought that would be my last sighting of the year. That is one tough insect! At Bear Creek, a few grasshoppers were still chirping, a bit forlornly, in the tall grass as well and could still be seen springing about on southern slopes in the park. Amazing.
And Just One Special Leaf this Week:
Isn’t the Quaking Aspen (Populus tremuloides) a lovely tree? They shimmer silvery green in the summer and shower golden leaves in the fall. It’s a very common and short-lived tree with smooth, light bark that’s often mistaken for birch. And as Michigan Flora says, it’s “one of the few deciduous trees of the boreal forest to the north of Michigan.” Another resident from the far north! That Tree Sparrow must have passed thousands of them on the way here. Maybe that’s why I saw my first Tree Sparrow of the year right across from the Aspens on the park’s northern loop. This week, in those stiff winds and rain, the Aspen’s dancing leaves went flying, leaving a carpet of gold on some paths at Bear Creek.
Now for those “Lovely but Lethal” Plants and Animals
It’s tough not to love White-Tailed Deer (Odocoileus virginianus). After all, who doesn’t love to see those “doe eyes” gazing our way?
However, deer are seriously over-populating the landscape here and elsewhere. According to the Nature Conservancy, “No native vertebrate species in the eastern United States has a more direct effect on habitat integrity than the white-tailed deer.” The huge number of deer changes the landscape as they prefer to eat native plants, like Common Trillium, for instance. This feeding has reduced the density and height of forest wildflowers and make more room for invasive plants to spread. Their consumption of acorns also has an effect on the tree canopy in the woods. Deer are native to Michigan and much-beloved by both nature-lovers and hunters, so finding a solution to their over-abundance is a real challenge.
As we posted separately, one of the worst actual killers in our parks is Oriental Bittersweet (Celastrus orbiculatus) – which was very apparent this week in the park. Its yellow leaves, yellow capsules and red fruit can be seen from every path twisting its way up and across trees and bushes. Introduced as a landscape plant, this striking but lethal vine kills trees and bushes in three ways. It winds aggressively around the trunks of trees to get to the sunlight at the top, girdling the tree until it chokes the tree to death.
It also creates so much weight at the tops of trees that once they are weakened by the Bittersweet, they can be blown over in the wind. They also climb over bushes so densely that they simply steal the sunlight and nutrients from the host plant and any plant nearby. So please don’t pick it, don’t make or buy wreaths of it and don’t try to pull the heavy vines down yourself because you could get seriously hurt! Please see our post on how to rid our parks or your property of this beautiful killer.
Autumn Olive (Elaeagnus umbellata) has been the bane of Bear Creek for a long time. The northern end of the park is full of this invasive bush with its fragrant flowers in the spring and its red berries in the fall. This woody shrub can literally crowd out native shrubs and plants as it has, along with other invasives , on the large loop at the north end of the park.
Now a new invasive tree is competing to be the most problematic and it too is lovely. (Most invasives are pretty; that’s why people plant them in their landscapes!) Friday morning I counted 16 small to medium-sized trees of this new problem for Bear Creek in one small corner near the center pond. It’s called Callery Pear (Pyrus calleryana) – another lovely, but lethal invasive plant.
Of course, native trees can get out of hand, too, like Box Elder (Acer negundo), actually a not-so-wonderful kind of maple . Look at the number of samaras (a fruit with wings attached to carry seeds) in this one small clump on a large tree at the bottom of the western slope. There are a lot of box elders on the western slope for that very reason! Though the multiple trunks are often thin and the trees are short-lived, it can quickly colonize an area and crowd out other trees and plants.
Nature is remarkably resilient. If we can give it a bit of help through careful stewardship, we can control these lovely and lethal plants and animals so the native ones can take their proper place in the landscape and the non-native ones can slowly be eliminated or at least controlled so they don’t irrevocably change the diverse native landscape that nature provided for us. So consider joining in our stewardship events (see the Stewardship Events tab above) as we weed and plant to help Bear Creek and our other parks thrive in all their natural glory.
A note about “This Week at Bear Creek”: My blog posts will probably slow some between November and February since late fall and winter are more static times in the park – and occasionally the weather will make it tricky to get out with my camera! So please consider “following” Natural Areas Notebook, so that you’ll get an email when a post goes up. I love doing this blog, so whenever I see some changes in the wildlife or something unusual in the park that I think might interest all of you this season, I’ll be here! Thanks so much for your support and interest as we made our virtual walks together through the spring and summer! Let’s see what late fall and winter bring!
Footnote: My sources for information, as well as Oakland Township Stewardship Manager Dr. Ben VanderWeide, are as follows: Ritland, D. B., & Brower, L. P. (1991);Stokes Nature Guides: A Guide to Bird Behavior Volumes 1-3, Allaboutbirds.org, the website of the Cornell Ornithology Lab at Cornell University; Wikipedia; http://www.butterfliesandmoths.org; Herbarium of the University of Michigan at michiganflora.net.; various Michigan Field Guides by Stan Tekiela; Butterflies of Michigan Field Guide by Jaret C. Daniels; University of Wisconsin's Bug Lady at www4.uwm.edu/fieldstation/naturalhistory/bugoftheweek/ for beetle info http://www.migrationresearch.org/mbo/id/rbgr.html for migration info, and invaluable wildflower identification from local expert, Maryann Whitman; experienced birder Ruth Glass, bird walk leader at Stoney Creek Metro Park for bird identification; Birds of North American Online; Audubon.org.