Besides being known for their vocal repertoire, Northern Mockingbirds are famous for pugnacious defense of their territory, nest, and young. Even more than most songbirds, Northern Mockingbirds aggressively stand guard over their nestlings as well as their young fledglings. Potential predators risk being mobbed and chased by nesting mockingbirds. While the female incubates, the male spends most of his time perched high on trees or rooftops, acting as a sentinel, and will chase away any animal (including humans) that approaches the nest. Northern Mockingbirds have also been known to join forces with other birds, including cardinals, thrashers and doves, to chase away potential nest predators.
We are at the time of year where finding a young bird on the ground is not unusual, and many well-meaning people assume that if a bird can’t fly, it has been abandoned by its parents. While some of these birds may be young that have fallen out of their nest, the fledglings of many species spend as many as two to five days on the ground before they can fly any distance. While they are on the ground, the birds are cared for and protected by their parents and are taught vital life skills (finding food, identifying predators, flying). To deprive such a fledgling of this developmental stage by removing it from its parents is to lessen its chances of survival, so it’s behooves us to be able to tell whether or not a young bird belongs out of the nest or not.
If the young bird is nearly naked or covered with down, not quill feathers, or its eyes haven’t opened, it is obviously a nestling. If you can’t find its nest, a berry basket in the vicinity of where you found it, suspended from a branch, is a good facsimile. Birds have a poor sense of smell and very strong parental instincts and more often than not continue to care for their young after a disturbance, although it may be a few hours before they do so. If, after several hours, there is no sign of a parent, a local museum or nature center should be able to direct you to a nearby wildlife rehabilitator.
Fledgling birds, birds that have voluntarily left their nest, are usually fully feathered and have a very short (one inch or so) tail. They are able to walk, hop and flap, and they may attempt short flights. You may not see them, but a parent or two is nearby, keeping an eye on them, feeding them and teaching them how to survive on their own (see insert). These are the birds that humans often mistakenly “rescue.” If you find a fledgling, it should be left alone or, at the most, placed in a nearby shrub. If possible, keep people and pets away so the parents will continue to care for it until it can fly. (Photos: fledgling and attending adult Common Grackle)
White-breasted Nuthatches maintain their pair bond throughout the year. In the spring, after mating, the female builds her nest, lining the tree cavity (natural or old woodpecker hole) with fur, bark, and lumps of dirt and then making a cup nest of grasses and bark inside the cavity. She then lays her 5 – 9 eggs and incubates them for roughly two weeks, during which time the male brings her food.
After the eggs hatch, both parents provide their nestlings with food until they fledge. Initially the female remains with the young, and the male brings food for both her and the nestlings. His trips become more frequent during the first few days, starting at about 7 trips an hour and increasing to 13. After three or four days the female also participates in food gathering, as much or more than the male.
The average day length in June is approximately 15 ½ hours. At 26 deliveries/hour (13 per parent) that comes to a total of around 400 foraging trips a day for the majority of the 26 days before White-breasted Nuthatch nestlings fledge. Impressive, especially when you consider that many of these trips involve not only delivering food but also removing the nestlings’ fecal sacs.
“Peter – Peter – Peter.” “Peter – Peter – Peter.” The song of the tufted titmouse is one of the first bird songs heard in late winter. Unlike its scratchy, nasal call note, the titmouse’s song is a relatively loud, clear, two-note whistle which is repeated rapidly up to 11 times in succession. If you become aware of it, it can even become a bit monotonous. While it is mostly males that do the singing, females sometimes give voice to a softer version of this song.
To hear a tufted titmouse’s song and call notes, go to http://www.langelliott.com/wp-content/mary-holland/tufted_titmouse.mp3. (Sound recording © Lang Elliott – langelliott.com & miracleofnature.org)
The woods have become relatively quiet in the last few weeks. A majority of songbirds have mated and nested, so there is no need to reinforce pair-bonding with song. However, some late nesters, including the Hermit Thrush, are still on eggs and the males are still singing.
The Hermit Thrush makes up for its rather drab appearance with its melodious, haunting, flute-like song. The Hermit Thrush’s song is similar to that of its close relative, the Wood Thrush, but it starts with a single, clear note which the Wood Thrush’s song lacks. The Hermit Thrush doesn’t sing during migration or on its wintering grounds, so we are now privilege to its last lyrical songs of the year. To hear a recording, go to http://langelliott.com/mary-holland/hermit_thrush_by_Ted_Mack_Adirondacks_1994.mp3. (Sound recording © Lang Elliott – langelliott.com & miracleofnature.org)
Equality of the sexes has yet to reach some avian species. Among them is the Ruby-throated Hummingbird, the only species of hummingbird that breeds in the Northeast. After courtship and mating takes place, the male has next to no contact with his mate(s), possibly visiting them during nest construction, but he does not lift a feather to assist in raising their offspring. By herself the female selects a nest site, builds a nest (six to ten days), lays two eggs, incubates the eggs (12 – 14 days), broods them (9 days), removes their waste, or fecal sacs, for the first two days (after which the nestlings eject their droppings from the rim of the nest) and feeds them (a total of 22 – 25 days — while young are in nest, and for 4 – 7 days after they fledge). Males spend the summer feeding, preening, bathing, stretching their wings and fanning their tails, sleeping, roosting and sunbathing. Not a bad life for him; an exhausting one for her. (Thanks to Jeannie Killam and Terry Ross for photo op.)
The diet of both Cedar and Bohemian Waxwings is primarily sugary fruits throughout most of year. Research shows that they can subsist on this diet exclusively for as many as 18 days. However, in winter when feeding on fruits, they also feed on buds and available insects. In warmer months, waxwings will fly out over water from exposed perches, much like flycatchers, and snatch emerging aquatic insects such as mosquitoes, midges, mayflies, caddisflies and dragonflies out of the air. They also glean for vegetation-borne insect prey, such as scale insects. At this time of year they are taking advantage of winter stonefly hatches over open streams. (photos: bohemian waxwing & stonefly)
The mournful lament of the male mourning dove is often one of the first songs heard in the early spring. The frequency of this call builds to a peak from mid-May to mid-June. As in many other pigeons and doves, the Mourning Dove’s main call, or “perch coo” (coo-oo, OO, OO, OO) is an advertising call, sung in order to attract a mate. Unmated males often establish perches within their territory from which they repeatedly sing.
A shorter nest call is used by a paired male to attract his mate to a potential nest site. The male then gathers nesting material and presents it to the female while standing on her back. While she constructs the nest, he continues to use the nest call to maintain a bond with his mate. Once the nest is built, this call diminishes. You can hear Mourning Dove calls at http://www.allaboutbirds.org/guide/mourning_dove/sounds, although to my ear, it’s hard to distinguish the perch call from the nest call in these recordings.
Most songbirds have one complete molt every year, in the late summer. Some, like the American goldfinch, have another (partial) molt in the spring. Last fall male goldfinches molted, replacing many of their bright yellow feathers with drab, greenish-gray feathers, so that they closely resemble females during the winter. Goldfinches start their partial molt in February, and in the next month or two, males will once again become bright yellow beacons. No-one can illustrate the subtle seasonal plumage changes of a male American goldfinch better than David Sibley: http://www.sibleyguides.com/2012/05/the-annual-plumage-cycle-of-a-male-american-goldfinch/ (Photo: male American goldfinch in March)
At 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.
Regardless of the deep snow that remains on the ground and the frigid temperatures we’ve had recently, spring has announced itself with the arrival of red-winged blackbirds this week. Most redwings that breed in New England migrate approximately 500 miles further south to spend the winter. In the spring, males begin migrating first, flying north in flocks during the day to their breeding grounds. (In the fall, females depart first.) While they eat primarily insects during the breeding season, redwings subsist mainly on seeds and grain this early in the season. Before you know it, females will return, and up to fifteen of them will be nesting on the territory of each male (though he doesn’t sire all of the nestlings).
Seeds, including cultivated grains, grasses, weeds and berries, make up 99 percent of a Mourning Dove’s diet. Because they can find enough food to sustain themselves, Mourning Doves are permanent residents, remaining year round, even in northern New England.
These birds feed on the ground and in the open, consuming 12 to 20 percent of their body weight per day, or 71 calories on average. Mourning Doves swallow the seeds and store them in an enlargement of the esophagus called a crop. Once their crop is filled (the record is 17,200 bluegrass seeds in a single crop), they can then fly to a protected area where they can safely digest their food.
Tufted 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.
Gray catbirds begin their nocturnal migration to wintering grounds in late August and early September. The last of the stragglers are now passing through northern New England. Catbirds winter from the southern New England coast south to Panama, with concentrations on the U.S. Gulf coast and the Yucatan Peninsula. Those individuals that winter in the Yucatan Peninsula and Central America cross the Gulf of Mexico, and in order to do so they put on so much fat (during fall migration their mass may increase to 150% of lean body mass) that it approaches the upper limit of what flight allows.
During the breeding season, insects make up the bulk of a Red-winged Blackbird’s diet, but during the rest of the year, plant seeds are preferred. While the seeds of ragweed, corn, oats and smartweed are more staple food sources, cattail seeds are not overlooked. At maturity, and under dry conditions, the cattail spike bursts, releasing the seeds (some estimates are as high as 228,000 seeds/spike). When this happens, blackbirds take advantage of the easily accessible source of food, but the minute size of each seed (.0079 inches long) means obtaining a meal is a labor-intensive endeavor.
The Hermit Thrush is often one of the last thrushes to leave its breeding grounds in the fall — peak migration is between the end of September and the middle of October. High pressure, clear skies and wind from the north usually produce many sightings of this bird at this time of year. Unlike many other species of thrushes that winter in Central or South America, the Hermit Thrush is not a long distance migrator, and does not cross the Gulf of Mexico. Approximately one-third of all migratory flights end after only two to three hours of flight. Typically it makes several two-to-six-day stopovers to refuel before reaching its wintering grounds in southern U.S. and Mexico.
The Hermit Thrush is a nocturnal migrant, often departing roughly half an hour after sunset (over half of departures occur within 60 minutes after sunset and none after midnight) with most flights ending about 40 minutes before sunrise (none later than 20 minutes before sunrise). (Flight information from Birds of North America Online)
Inadvertently, the person responsible for my being able to photograph a Saddleback Caterpillar was not mentioned in yesterday’s post. Many thanks to Rick Palumbo for his extraordinary help with this endeavor.
Brown Creepers –insect-eating, bark-gleaning, little brown birds — are occasionally spotted as they circle their way upwards around and around a tree trunk, probing under bark with their thin, curved beaks for their next meal. Because they are so well camouflaged it is easy to miss them. Your chances of becoming aware of their presence are increased if you become familiar with the high, thin but surprisingly rich song males sing to establish territories on their breeding grounds this time of year. Although they continue to sing through the nesting period until their young have fledged, male brown creepers are most vocal early in the season, when they are staking out their territory. You can hear their song by going to http://www.allaboutbirds.org/guide/brown_creeper/sounds and clicking on “sound.”
The primary food of Cedar Waxwings is fleshy fruits that have a high sugar content. Because these birds rely on ripening fruit to feed their nestlings, they are among the latest birds to nest in the Northeast. During the winter they tend to be nomadic, wandering from one sugary fruit supply to another. In the past, juniper berries have dominated their winter diet, but waxwings are increasingly turning to ornamentals such as non-native honeysuckle. (Occasionally waxwings with orange, not yellow, terminal tail bands are seen; this change in color has been attributed to their change in diet.) The fruit of Highbush Cranberry, being consumed in this photograph, is quite acidic and has a low sugar content. It is eaten by most songbirds, including Cedar Waxwings, only towards the end of winter, when sweeter fruit is in short supply.
Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button
As opposed to humans, who use the entire bottom of their feet for support, birds stand and walk only on the ball of their foot and with their toes. When you look at a bird’s leg, what appears to be its knee, bending backward instead of forward as it does in humans, is actually its heel.
Most birds have four toes, arranged differently according to the life style of the bird. Songbirds, as well as most other birds, have three toes pointing forward and one pointing back. Most woodpeckers, being active climbers, have two toes pointing in each direction, which provides added clinging support. The outer toe (of the three forward toes) of ospreys and owls is reversible, so that they can have two toes in back should they need to get a better grasp on slippery fish or other prey. Some birds that do a lot of running, such as sanderlings and most plovers, have only the three forward toes. (Photo: Mourning Dove tracks)
The first reports of Red-winged Blackbird sightings are coming in, and with two feet of snow in some places, frigid temperatures, and very few insects in flight, one can’t help but wonder how they are surviving. A number of factors allow Red-wings to sustain themselves in these conditions, including the fact that their foraging is not restricted to one habitat – they look for food in marshes, pastures, overgrown fields, shores of lakes and ponds and windblown, exposed corn fields and crop lands. Secondly, they look for food in and on a variety of substrates, including but not limited to tree trunks and vegetation, which are accessible even with snow on the ground. Thirdly, they are very adept at gaping – forcing their bill open against the resistance of bark, etc. in order to reach into the crooks and crannies where insects are overwintering. And lastly, their diet fluctuates with the food that is available. During the breeding season, the majority of a Red-winged Blackbird’s diet is insects, and during fall, winter and early spring, Red-wings are primarily plant eaters – weed seeds, tree seeds and in agricultural areas, grains. In many ways, Red-winged blackbirds are more successfully adapted than humans are to this interminable winter!
By this time of the year fruit-eating birds have, for the most part, devoured the choicest fruits available in winter. What remains are the fruits-of-last-resort. While Staghorn Sumac fruits may not be a preferred food, they are an important source of winter sustenance for many species of birds, including bluebirds (pictured), cardinals, chickadees, jays, robins, waxwings, crows, mockingbirds and starlings. Some of the best late-winter birding occurs near stands of this shrubby relative of poison ivy. Can you find the four Eastern Bluebirds feeding on sumac in the photo?