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Feather Fact #4 – A light Meal for Grebes

Pied-billed Grebe chick. Feather Fest Countdown Feather Fact #4

Feather Fact #4 – Feather light Meals for Grebes

If you were a newly hatched Pied-billed Grebe chick, one of your first meals might be feathers. Not by accident either, grebe adults also eat feathers as well as feed them to their young. As a matter of fact, research has shown grebe stomach contents consisting of 52% feathers. Talk about eating light!

So where do they get all the feathers to ingest? They pluck out their own, primarily from the flank area. Those feathers actually continue to molt throughout the year, an adaptation that renders a continuous supply of the fluffy meal. Now, you are surely asking yourself, so why are they eating all these feathers anyway? The leading theory seems to be that it helps them with pellet casting once any hard bony bits in the stomach are digested, and that the pellet ejections minimize the buildup of parasites.


Source: Muller, Martin J. and Robert W. Storer.(1999).Pied-billed Grebe (Podilymbus podiceps), The Birds of North America (P. G. Rodewald, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America: https://birdsna.org/Species-Account/bna/species/pibgre

Bird nesting periods, tree cutting, the law and you

An adult American Robin arrives with a fresh worm to feed a begging fledgling in a backyard birdbath. (Photo: Connie Morgenstern)

Did you know that causing harm to a migratory bird or destroying its nest or eggs is illegal and contravenes the Migratory Birds Convention Act, 1994 (MBCA) and its regulations ? Before cutting down or pruning trees, this is something to consider. If your backyard is home to a bird family, causing them stress by destroying their habitat during the time they are intensely concentrating on the hard work of brooding, feeding and tending to young can have dire consequences.

Although birds vary in their tolerance to human proximity during the nesting period, they may abandon nests containing eggs or young if they feel threatened, even if they are situated in a tree merely in the vicinity of the one being felled. Tree cutting activity can also potentially result in nest and/or egg destruction or the killing of nestlings. Likewise, if scared off the nest too early, the survival chances of fledglings are limited.

While people often tend to think of birds as nesting during the springtime, that isn’t necessarily the case. Nesting times actually range from early spring to late summer depending on the species and geographical location. Most songbirds are among those birds born without feathers (known as altricial young) and are unable to fend for themselves for a while after hatching. However, it is important to keep in mind that “nesting period” doesn’t only refer to the time when the babies are still in the nest. Many bird parents continue to care for and feed their fledglings during the critical developmental period where the young birds learn to forage for themselves.

For example, a Downy Woodpecker (Picoides pubescens) chick will take its first flight at age 18-21 days. It will leave the nest cavity by making a short flight to the nearest branch and then most likely sit there motionless for the rest of the day. In the meantime, the parents occasionally return to feed it while also returning to the nest to feed the remaining nestlings. A fledgling remains under parental supervision for at least three weeks after fledging as it learns to forage on its own. During this time Woodpecker parents teach their young to be alert to predators as well as how to locate food sources, which may even include leading them to backyard feeders!

American Robin (Turdus migratorius) nestlings fledge at around 12-14 days of age and become fearful of intruders several days before the “big event” approaches. As a consequence, if frightened at this stage, the young birds may fledge prematurely. If the parents find them after this happens they’ll likely feed them, but the fledglings’ chances of survival are greatly reduced as they become easy targets for lurking predators. Normally, an adult male Robin will continue to feed its young after fledging, while the female continues to feed the babies remaining in the nest. Then, once the entire brood has left the nest, both adults will continue to feed them for several days afterwards.

Another common backyard feeder bird, the Chipping Sparrow (Spizella passerina), usually fledges at 12 days of age; but survival is greatly limited If hatchlings are scared off the nest prior to 9 days of age. Even after leaving the nest at a more respectable maturity, the young remain very vulnerable. Chipping Sparrow fledglings continue begging for food from their parents for another 3 weeks before beginning to search for food on their own.

While people often assume that there aren’t birds nesting on their property, keep in mind that just because you don’t see a nest in a particular tree, it doesn’t mean there isn’t one! Birds are very good at camouflaging their nests (for good reason!). Different species build their nests at different heights, and those high up among the leaves may be extra hard to spot. Tiny Hummingbird nests are probably one of the hardest to find. Incidentally, the Ruby-throated Hummingbird, the only Hummer species that breeds here in Quebec, is one of the birds that nests later in the summer. Some birds species will build their nests on or quite low to the ground, something  the careful gardener should also be mindful of when doing yard work.

Resources:

For a list of birds covered under the Migratory Birds Convention Act and a number of other interesting resources, visit the Environment and Climate Change Canada website.

Consult the Bird Studies Canada Nesting Query Tool here.

The private lives of bird moms

A Chipping Sparrow collecting nesting material. (Photo: Connie Morgenstern)

The Private Lives of Bird Moms: a peak into the nesting habits of 5 common backyard birds

Here’s a look at some familiar bird moms and a few nesting behavior traits that may surprise you. The following birds are common backyard visitors and likely very familiar, but do you know some of the following more intimate details about their lives?

#1. American Crow

Crow mom has clearly figured out how to delegate to get things done and make sure that the rest of the family doesn’t just sit idly by and leave her to do all the work! Crows mate for life and carry out the tasks related to nest building and caring for their offspring with help from their older offspring from previous broods. Once the female has laid a clutch she will sit on the nest to incubate the 6-9 eggs, sitting on the nest all night and for the majority of the day. Fortunately, unlike a human mom who might be inclined to order out for pizza at this point, Crow mom has her older offspring out searching for food to bring back to feed her. In the meantime Crow dad is sitting somewhere nearby looking out for predators who might want to usurp the nest. If for some reason the pair doesn’t have this community support, the male will spend more time away looking for food. For the short time the female is off the nest, she will stretch, preen and defecate then rush back to resume her duties at home.

Once the eggs begin to hatch both the dad and older offspring pitch in with housekeeping duties such as carrying away the egg shells and helping to feed the nestlings. When the nestlings have reached the point where they are able to regulate their own body temperatures, Crow mom will start to join in the food gathering duties. Once leaving the nest, the fledgling’s flight skills aren’t quite fully developed and so the parents continue to feed them for several weeks, then help them learn to find food on their own.

#2. American Goldfinch

The American Goldfinch nests later than other songbirds. It waits until summer when the milkweed and thistle plants that it uses for nest building and food are available.

Paired couples choose the nest site together but the female builds the nest which may take up to 6 days. Nest are so tightly woven they can even hold water! The nest is securely lashed to a branch using spider webs. Goldfinch mom lines the interior of the nest with the soft downy fibers she obtains from thistle, dandelion or cattails seeds. Both parents feed the young by regurgitating semi-digested seeds. American Goldfinches will only rarely feed their young insects.

#3. Chipping Sparrow

Females arrive on the breeding territory a week or two after the males and pair formations begins soon afterwards, as does selecting an appropriate nest site. Reminiscent of a human couple looking for a place to build their dream house, the female Chipping Sparrow will try out a few locations first. She will squat in place to size up a location, maybe even pick up a bit of vegetation lying about to mimic nest building in the given space and then repeat the behavior in several different spots before deciding on the most suitable one.

Female chipping sparrows have been observed returning to the same nesting sites from year to year. While they won’t reuse a nest, they are known to dismantle old ones and recycle the materials. Preferred construction materials include fine plant fibers such as rootlets and dried grasses. In addition,  they also use a higher proportion of animal fur to line their nests than do other birds and are even known to pluck hair from live animals! As a matter of fact, the Chipping Sparrow’s love of horse hair as a nesting material earned it the nickname “hair bird” back in the days when horses and farms were more plentiful.

During the egg-laying stage the female returns once a day to lay an egg and may abandon the nest if disturbed. During incubation the male will feed the female. For the first few days after the chicks have hatched, the parents will feed them seeds. This is unusual as most songbirds feed their chicks a high protein insect diet from the beginning.

#4. Mourning Dove

Although the soft cooing vocalizations of the Mourning Dove are a familiar sound to many of us and may help to make this bird an endearing presence, Mourning Doves can seem a bit quirky. Unlike the American Goldfinch, they certainly won’t win any nest building awards; nest construction can be so flimsy that eggs may even fall through the bottom! The female constructs the nest with materials brought to her by the male who sits on her back while she lays them in place. This has been described by one author as seeming as if he is looking over her shoulder!

However, on the more remarkable side of things, Mourning Doves are one of the few birds that have the ability to suck; this is useful during the first few days of a nestling’s life when it drinks “crop milk” from either parent’s bill. While many species have crops that are used for food storage, Mourning Dove crops are somewhat unique. The enlarged chambers in the esophagus of both sexes produce this “milk” which has a cottage cheese like consistency. Packed full of  protein, fat, antioxidants and immune enhancing properties, it is fed to the nestling for the first few days of life at which point seeds are added to the nutrient mix. Incidentally, the only other species that share this ability are pigeons, flamingos and some penguins.

#5. White-breasted Nuthatch

White-breasted Nuthatches mate for life and remain on their territory throughout the year. Yet despite their long term association, the male carries out the courtship behavior of  feeding the female during the nest building and egg laying stage every year anyway. This is a typical behavior among birds and It is believed one purpose of such displays is to help stimulate the female’s ovulation.

Nuthatches nest in naturally occurring  cavities but are also perfectly happy to use old woodpecker holes. While the White-breasted Nuthatch doesn’t actually do any of its own cavity excavation, it will occasionally do a bit of DIY remodeling and enlarge a hole entrance. In terms of interior nest construction, the female is the handy one of the pair. While the male helps haul home materials, the female will construct a cup shaped nest of rootlets, bark flakes and grasses inside the cavity to prepare for their one brood of the season. The floor of the cavity is lined with bark, hair, fur, feathers, lumps of earth or rootlets. Although only the female broods, both parents feed the young and share the housekeeping duties of removing fecal sacks from the nest.

Sources and Resources:

Erickson, Laura, and Marie Read. Into the Nest: Intimate Views of the Courting, Parenting, and Family Lives of Familiar Birds. North Adams, MA: Storey, 2015.

https://www.allaboutbirds.org/
https://birdsna.org/Species-Account/bna/home

 

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