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Black-capped Chickadee

Cavity-nesting Birds Wasting No Time

4-21-17 black-capped chickadee nest building IMG_4765There are roughly 85 species of North American birds that are cavity nesters – birds that excavate nesting holes, use cavities resulting from decay (natural cavities), or use holes created by other species in dead or deteriorating trees.   Many of them get a jump start on open-nesting birds, due to added protection from the elements. Barred owls, titmice, chickadees, wood ducks, woodpeckers, bluebirds, mergansers – many have chosen a nest site and are busy excavating, lining a cavity or laying eggs long before many other species have even returned to their breeding grounds.

The reduced risk of predation a cavity nest experiences is reflected in several ways:  many cavity-nesters have larger clutches of eggs than open-nesting birds and cavity-nesting young also spend a relatively longer period of time in the nest before fledging. When in the woods, keep an eye out for snags (standing dead trees) and stumps, for they provide housing for many cavity-nesting birds.  (Photo: Black-capped Chickadee removing wood chips from the cavity it’s excavating in a rotting stump.)

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Woodland Recycler

4-7-17 chickadee on scat 116The ability to find food is crucial for all creatures.  It involves looking in every potential location, including the waste material of other animals.  Nothing goes to waste in the natural world, and I was fortunate to observe an example of this recycling phenomenon recently in bear-inhabited woodlands.

Even though feeding birds is discouraged at this time of year due to the seeds’ appeal to hungry, emerging Black Bears, many find it a hard habit to stop. Inevitably Black Bears will smell the seeds in feeders and help themselves to them.  If this continues long enough, the bears will become habituated and eventually this can lead to their being considered a nuisance, which can lead to their demise. Thus, it’s best to stop feeding birds now that Black Bears have emerged from hibernation.

That said, those who continue to fill feeders in the spring and have had them raided by bears need not fear that their birds are without recourse should they find the feeders empty or missing. Much of what goes in comes out, and bears deposit their seed-laden scat throughout the woods, creating ground “feeders” for all kinds of creatures. In this instance, a Black-capped Chickadee repeatedly helped itself to uncracked sunflower seeds amongst a great deal of millet and sunflower seed husks in the scat of a Black Bear.

This post is dedicated to Sadie Brown, Solid Waste & Recycling Coordinator for the town of Melrose, MA.

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Birds & Burdock

2-15-16 bird caught on burdock by Holly BroughIMG_5814The phenomenon of North American birds being killed by becoming entangled in Common Burdock (Arctium minus) has been documented since at least 1909, when one observer (in A.C. Bent’s compilation) described finding a multitude of Golden-crowned Kinglets in Common Burdock’s grasp:

They were visible in all directions, scores of them sticking to the tops of the clumps on the most exposed clusters of heads. The struggle had ended fatally for all that I saw, and its severity was evidenced by the attitudes of their bodies and the disheveled condition of their plumage. I examined a number of the burdock heads to determine that attraction had brought the kinglets within range of the hooks, and found insect larvae of two species present in considerable abundance.

Typically this phenomenon involves birds that are seeking either insects that are inhabiting the seed heads, or burdock seeds. The birds’ feathers get caught by the hooked bracts (modified leaves) that surround both the flower heads and seed heads of burdock. Small birds such as kinglets, gnatcatchers, goldfinches, nuthatches, hummingbirds, chickadees, warblers and siskins are the usual victims, but larger birds, including a Blue-headed Vireo and a Barn Swallow, have been caught as well. Most of these birds were found with their wings and tail spread, and caught by many parts of their bodies. The more they struggled, the more their feathers became entangled. Victims are not limited to birds — in 1925, a dead bat was discovered caught in a patch of burdock. (Photo by and thanks to Holly Brough)

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Goldenrod Ball Galls Provide Important Source of Winter Food for Downy Woodpeckers

12-11-15 goldenrod ball galls 058A number of insects cause goldenrod plants to form galls – abnormal growths that house and feed larval insects. The Goldenrod Ball Gall is caused by a fly, Eurosta solidaginis. The fly lays an egg on the stem of a Canada Goldenrod (Solidago canadensis) plant in early spring, the egg hatches and the larva burrows its way into the stem; the plant reacts by forming a gall around the larva. The larva overwinters inside the gall, pupates in late winter and emerges in early spring as an adult fly. Prior to pupating, the larva chews an exit tunnel to, but not through, the outermost layer of gall tissue. (As an adult fly it will not have chewing mouthparts so it is necessary to do this work while in the larval stage.)

Downy Woodpeckers (and Black-capped Chickadees) have discovered this abundant source of winter food, and dine on the larva after chiseling a hole into the gall. Downy Woodpeckers tend to make a tidy,narrow, conical hole by pecking, while Black-capped Chickadees tend to make a messy, large, irregular hole by grabbing bits of the gall with their bill and tugging them free. While woodpeckers prefer larger galls that are located high on goldenrod plants growing near wooded areas, these are not the only factors taken into consideration.

A woodpecker extracts the fly larva through the tunnel the larva excavates prior to pupating, as this facilitates rapid removal of the larva. Downy Woodpeckers can determine whether or not a gall has an exit tunnel, and if it doesn’t, they usually abandon the gall without drilling into it. The likelihood of smaller parasitic wasp larvae occupying the gall (and a plump fly larva not being present) is much greater if there is no exit tunnel, and these smaller prey apparently are not always worth the woodpecker’s time or energy.

NB: Correction: this week’s Mystery Photo was of a Gray Birch (Betula populifolia) bract, not a Paper, or White, Birch (Betula papyrifera) bract. While similar, there are differences between these two species of birch that I should have recognized (especially when looking at the leaf!). Thanks to Kathy, an alert blog reader, who caught this error.

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Black-capped Chickadees Starting to Build Nests

3-13-15  black-capped chickadee and Emma's hair 067At least two to four weeks before one would expect to find a black-capped chickadee building a nest, one was busily collecting hairs shed by my chocolate lab yesterday. In addition to fur, chickadees line their nest with grass (not available yet here), down and moss (hard to come by with two feet of snow still on the ground). Chickadees are able to nest this early in part because they nest in cavities, which offer them protection from the elements. Not having bills strong enough to hammer out cavities in living trees, chickadees rely heavily on rotting stumps for nest sites — the wood in them is punky and easy to remove. Birch, poplar and sugar maple snags and stumps are preferred nesting trees. If you want to provide chickadees and other birds with nesting material, take advantage of the fact that dogs and cats are shedding now, and recycle their fur.

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Tufted Titmice Caching Seeds for Winter Consumption

tufted titmouse2  379Tufted Titmice and Black-capped Chickadees are in the same family (Paridae), and share several traits, one of which has to do with securing food. They are both frequent visitors of bird feeders where they not only take seeds and soon thereafter consume them, but they also collect and cache food throughout their territory for times when there is a scarcity of food. Tufted Titmice usually store their seeds within 130 feet of the feeder. They take only one seed per trip and usually shell the seeds before hiding them.

In contrast to most species of titmice and chickadees, young Tufted Titmice often remain with their parents during the winter and then disperse later in their second year. Some yearling titmice even stay on their natal territory and help their parents to raise younger siblings.

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Honeybee Scavenger

2-10-14 chickadee & bee33 174If the weather warms up sufficiently in January or February, honeybees take advantage of it and use this opportunity to leave their hive to rid themselves of waste that they have accumulated since their last flight and to remove the bodies of dead honeybees. They don’t fly very far before dropping either their waste or their dead comrades on the snow. This ritual is quickly noted and taken advantage of by animals that are not hive dwellers and need constant fuel in order to survive the cold. Black-capped chickadees are one of these animals – the chickadee in this photograph repeatedly landed on the hive body, and if a dead bee was available at the hive entrance, the chickadee helped itself to it. Otherwise it would survey the snow in front of the hive and then dart down to scoop up a bee in its beak before flying off to a branch to consume its nutritious meal. (Note dead bees at the hive opening, awaiting being taken on their final flight. Screening keeps mice out, but allows bee to enter and exit.) Thanks to Chiho Kaneko and Jeffrey Hamelman for photo op.

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