Spring is famous for being baby season - but watching an eagle family is a unique and emotionally stirring event. We expect animal parents to be dedicated and attentive to their young, but raising these busy, ravenous youngsters requires full time dedication to meeting their needs. And having the opportunity to watch the relationships - not only between adult and baby, but also between the 2 small ones in this nest is a very fascinating experience.
Eagles are very long-lived birds, surviving for up to 30 years in nature. They will typically nest in forested areas that are closely adjacent to water, which is where their major food source is located. They like tall coniferous trees for perching, offering a wide expanse to survey. For nesting, their preferences are no different - they tend to use tall, sturdy conifers that often project above the surrounding canopy. This allows them easy access into and out of the nest, as well as excellent visibility - and makes access for ground-borne predators difficult. Most commonly, nests are built near the trunk high up in the tree, but below the crown (unlike the nests built by osprey who prefer to be above the highest part of the tree). Eagle nests are massive, and can take months to build -- and will be added on to year after year when the nest is reused. Both sexes bring materials to the nest, but the female does most of the placement - weaving together sticks and filling in cracks with softer grasses and mosses. The inside of the nest is lined with soft, fine material including downy feathers and greenery.
I am estimating the eaglets shown here to be approximately 6 weeks of age - and at this point, the parents are increasingly leaving the nest for longer periods of time, watching from a distance and leaving the area to hunt for food. Their presence doesn't go un-noticed by the corvids (crows, ravens, jays and such) in the area - who recognize that THEIR nests could easily be raided by the adult eagle. In fact, eagles will also take adult birds to feed to their young - so to watch the local "police squad" dive bomb the eagle near it's nest is, in and of itself, quite interesting to watch! Plucky brave birds protecting their young at their own peril -- and certainly quite the nuisance for the eagles.
Eagles will have only a single brood in a year, consisting typically of only 1-3 eggs. They incubate for 34-36 days, and once the eggs hatch, the parents increasingly leave the young alone while they search for food -- and requirements of these young eaglets is pretty massive given their extremely rapid growth rate.
This timeline is from eagles.org
The eaglets grow rapidly, they add about a half pound to a pound of body weight every week until they are about 9-10 weeks old, depending on if the eaglet is a male or female. Females are always larger.
At about two weeks, it is possible for them to hold their head up for feeding.
At about three weeks they are 1 foot high and their feet and beaks are very nearly adult size.
At about three to four weeks old the eaglets are covered in a secondary coat of gray down.
At about four to six weeks, the birds are able to stand, at which time they can began tearing up their own food.
At about three to six weeks, black juvenile feathers will begin to grow in. While downy feathers are excellent insulators, they are useless and must be replaced with juvenile feathers before an eaglet can take its first flight, some 10 to 14 weeks after hatching.
At about six weeks, the eaglets are very nearly as large as their parents.
At about eight weeks, the appetites of the eaglets is at its greatest. The parents will hunt almost continuously to feed them, meanwhile at the nest the eaglets are beginning to stretch their wings in response to gusts of wind and they may even hover for short periods. The eaglets grow stronger.
At about nine to ten weeks, they begin branching, this is a precursor to fledging.
Around ten to fourteen weeks, the eaglets will fledge, or fly away from, the nest.
Once the eaglets have fledged they may remain around the nest for four or five weeks, taking short flights while their primary feathers grow and strengthen. Their parents will still provide all of their food. The juvenile fledglings, with the exception of their color, look similar to their parents, but are nothing like them in behavior. The juveniles now have to learn to hunt, and they only what’s left of summer to learn. After that, they’re on their own. The first winter is the most dangerous and difficult part of an eagle’s life.
Although fish are the primary staple of Bald Eagle diets, they are not picky eaters - nor are the young birds. The parents will bring, and feed, everything they can find or steal to support the rapid growth of the young. Not only do they like fish (especially salmon, herring, and shad -- which are particularly available this time of year!) but they will also consume birds, reptiles, amphibians, mammals (such as foxes, rabbits, muskrats, and rabbits) and a variety of invertebrates such as crabs. When you have the ravenous appetite of teenagers to look after, you bring whatever you can back to the nest!
My observation is that the parent feeds one chick until it is entirely sated, and then begins to feed the second chick. However, if the first chick "busts in" for another mouthful, the parent allows the pair to squabble until a victor snatches the food from the mouth of the parent. I wonder if this perhaps might be an adaptation to maximize the success of at least 1 chick (rather than losing both) in times of food shortage -- if one young always gets all of the food it needs, it's chance of surivial should be higher than if both chicks are fed below necessary amounts.
The squabbles, although somewhat amusing to watch, are intense - and growing more significant with time. What started with squawking and beaking progressed over the days to pushing, shoving, and aggressive snapping. The cute downy babies are starting to grow juvenile feathers and learn the way of the world -- including that nice guys eat last.
Stay tuned to see how this lovely family continues to progress over the course of the summer - if you haven't subscribed to my blog, please send me your information on my contact page!
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