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Bird Nests

Tree Swallow Nestlings Well Fed

7-21 tree swallows 068Tree Swallow parents begin feeding their four to seven nestlings as soon as they hatch, and they continue doing so until their young depart the nest and sometimes for several days afterwards. The adult carries food in its bill and places it directly into the open mouth of a begging nestling. The small insects gathered by the parent may be formed into a rounded ball, or bolus, which they hold in their mouth or throat (often not visible to an observer). Both parents feed the nestlings, together averaging about ten to twenty deliveries per hour. During periods of peak nestling demand, parents may feed as many as 6,000 to 7,000 insects in a single day. (Thanks to Jeannie Killam and Terry Ross for photo op.)

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Juvenile Bald Eagles Fledging

7-17-15 juvenile eagle 003For several weeks before leaving their nest, young bald eagles constantly flap their wings, occasionally lifting themselves off the nest several inches in mid-air. Eventually they succeed in making short “flights” to nearby branches and then back to their nest. The young eagles are strengthening their wing muscles, practicing landing, and beginning to master flight.

Sometime between 8 and 14 weeks juvenile bald eagles leave their nest. Many fledge successfully, but up to half of the nest departures are unsuccessful, with the young ending up on the ground where they may stay for weeks before flight is achieved. During this time the parents usually continue to feed their young, but the juvenile eagles are far more vulnerable to predators. If the flightless, grounded juveniles are approached or threatened, or if they simply want to move from one spot to another, they walk or run on the ground (see photo).

The young bald eagle pictured was blown out of its nest prematurely and landed on the ground. Eventually it managed to fly back up onto a branch in the nest tree. The parents continued to feed the eagle while it was on the ground, as well as after it was back up in the tree. (Thanks to Linda and Roger Whitcomb for photo op.)

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Young Eagles Preparing to Fledge

6-11-15 eaglet 062For several weeks prior to their first flight from their nest, Bald Eagle nestlings practice flapping their wings to the point of lifting themselves up several inches into the air. This develops their wing muscles, flight coordination and landing ability.

At anywhere from eight to fourteen weeks of age, juvenile Bald Eagles fledge, or leave their nest. According to Birds of North American Online, up to half of young Bald Eagle nest departures are unsuccessful. The young land on the ground and may remain there for weeks before regaining flight ability. More often than not their parents will continue to feed them, but they are much more vulnerable to predation in this situation. Fledglings may continue to use their nest as a feeding platform for several weeks after leaving it, as they gain flight and foraging skills.

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Barred Owl Chicks View The World For The First Time

6-4-15  barred owl chicks2  100 Barred Owl eggs (usually two or three) are often laid in a tree cavity, where the adult female incubates them for roughly a month. Fuzzy, white, downy chicks hatch and remain inside the tree for four or five weeks while being fed by both parents. When the young owls are two or three weeks old, their white down is replaced with gray-buff secondary down, and they gain the strength to climb up the inside of the tree and peer out at the outside world. In and out they go, perching on the rim of the nest hole for half an hour or so as they await the arrival of their next meal, and then retreating back to the safety and warmth of their nest. (Thanks to Alfred Balch, naturalist extraordinaire, for photo op.)

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Great Horned Owlets Soon To Fledge

great horned owl 454Great Horned Owls are said to have a wider range of nest sites than any other bird in the Americas. Most commonly they use tree nests of other species, particularly Red-tailed Hawks as well as other hawks, crows, ravens, herons (Great Blue Heron nest pictured), and squirrels.

These month-old young owls have grown rapidly, from a weight of roughly an ounce at birth to about two pounds. They will weigh approximately 2 1/2 pounds when they fledge. By six weeks of age, young Great Horned Owls are climbing out of the nest and perching on nearby branches, and by seven weeks they are taking short flights.

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Cliff Swallows Building Nests

5-19-15 cliff swallow 719You may have heard of “lining” bees – following one honeybee after another, tracking them to their honey-laden hive. Recently I lined Cliff Swallows. My initial observation was of several swallows on a mud flat in the middle of a river, loading their beaks with mud and taking flight, all in the same direction. Knowing that their nests are made of mud pellets (900-1,200 of them), I knew that they must be nesting somewhere in the vicinity. The length of time between their departure from and return to the mud flat was quite short, so I deduced that the distance they were carrying the mud and depositing it couldn’t be too great. After heading off in the direction that the swallows were flying, I eventually discovered the very beginning of a colony of Cliff Swallow nests under the eaves of a nearby barn.

The building of a nest requires not only finding a source of mud, but also ferrying lumps of it (in their beaks) back to the nest site many, many times. Once a source has been found, its location is made known to all members of the colony, and they all make use of it. Cliff Swallows belonging to the same colony not only use the same source of mud, but gather it together as a group, and return to work on their nests all at the same time. They work in roughly half-hour shifts, after which they all take a break and forage for insects for ten minutes or so before resuming work.

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Eaglets Hatching

bald eagles2  254When eagle chicks hatch they are covered with light gray down and have brown eyes and pink legs. One parent, usually the female, spends most of the day in the nest with her young for the first three weeks, brooding and keeping them warm. The male provides most of the food during this time. After he delivers prey, she tears off small pieces and feeds them to the nestlings. The chicks gain weight rapidly – roughly ¼ pound a day – so that in three or four short weeks the young are nearly the size of an adult. Eaglets are roughly six weeks old before they are capable of tearing off food and feeding themselves, and at least eight weeks old before they leave the nest. (Note corn stalk that’s been incorporated into nest; photo: one-week-old eaglet & its mother)

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