Avian generations in the making – part 3A: raising and feeding babies

So here in North America, it’s approaching winter and it may seem a bit weird to have another blog at this time on birds raising their young. But I wanted to complete the series even though it has been delayed because of my volunteer activities and commitments the past month. Also, it is now late spring in the Southern hemisphere so for some people this is seasonal and there are other birds around them that are getting ready for babies, though different species than these American robins (Turdus migratorius). Because this part kept growing longer as I worked on it, I’ve divided it into two parts – this one on raising the babies until fledging and the next one on fledging and post-fledgling care. I hope all of you who read this will enjoy it no matter where you live.

It’s fascinating to me to watch the birds during their reproductive cycle; I always learn something new. Once parent birds have completed a nest to their liking, the female lays her eggs and proceeds to brood them, with some species sitting on the eggs almost full time right away and others taking breaks.

           

Carolina wren (Thryothorus ludovicianus)              Eastern bluebird (Sialia sialis)

An acquaintance recently told me about a friend of hers who commented that she had seen a very pregnant goose that was so fat, she was waddling. The acquaintance proceeded to give an avian reproduction lesson to her friend – a woman in her 80s – who apparently did not know all birds lay eggs! Even after babies hatch, the Canada goose (Branta canadensis) may still look well-fed!

Some bird species have young who are “precocial”, that is, they are covered with downy feathers and have open eyes when they hatch and are soon able to feed themselves. These species include turkeys and ducks, like these mallards (Anas platyrhynchos), and the young often leave the nest soon after birth (which makes them “nidifugous” – good Scrabble word!). The newborns may look fuzzy but it’s not long before they start to take after their parents’ looks.

Other birds, such as songbirds, are altricial (as are human beings) – they are naked and helpless at birth and require considerable care before they can walk, fly and feed themselves. If you have some in a nest that is easily observable (and you can take photos when parents are not there so you don’t distress them), it’s interesting to see how the babies develop.

               

Carolina chickadees (Poecile carolinensis) on 18 and 22 April           

Brown-headed nuthatches (Sitta pusilla) on 13, 25 and 29 April

 

 

Eastern bluebirds (below)

     

As the mother incubates the eggs, her mate will often feed her so she doesn’t have to leave the nest. This young osprey (Pandion haliaetus) was assiduous in bringing his female life companion fish. Then as the babies hatch, in many species both the male and female parents get busy bringing the young frequent meals.  It’s estimated that Carolina chickadees, for example, will bring over 5000 insects to their brood before fledging!

Northern mockingbird (Mimus polyglottos)

     

House finch (Haemorhous mexicanus)  and Red-headed woodpecker                (Melanerpes erythrocephalus)

              

Orchard oriole (Icterus spurius)                  Blue grosbeak (Passerina caerulea

  

Eastern phoebe (Sayornis phoebe)

In some species, the previous year’s young will help their parents with the new brood. Brown-headed nuthatches and American crows are examples of this. A pair of Canada geese that I observed this past spring seemed to have a domestic goose helping them out.

The parents have other chores, too. They must keep the babies safe from predators – Both American crows (Corvus brachyrhynchos) and common grackles (Quiscalus quiscula) will be chased away by songbirds, for example, because these birds will raid nests to eat eggs and babies. But the grackles must also protect their own young against the crows, pursuing them non-stop to drive them away.

 

For other birds, protecting the young can be more difficult. This mother wood duck (Aix sponsa) was raising her brood in a pond that was home to at least three large snapping turtles (Chelydra serpentina). Ultimately, another birder and I thought she only had two ducklings survive.   

Keeping the nest reasonably clean is another chore. The babies make this task a little easier than you might think because they defecate into a mucous membrane that forms a sac. When you watch a nest box, especially when it gets closer to fledging time, you can periodically see the parents flying out of the box with a white blob in their mouth, which turns out to be a fecal sac. They either discard it elsewhere or sometimes eat it for some nutritional benefit.

        

Brown-headed nuthatches

This year, I was surprised to have caught a female blue grosbeak during the cleaning – it appeared that she was actually pulling the fecal sac from the baby! Later, I read that some species stimulate defecation by prodding the babies’ cloaca so they can get on with the chore. I also caught a photo in which a baby bluebird had just presented its rear end to the parent for removal of a sac. I could imagine that some human parents might think a fecal sac would be a cool avian adaptation for their babies to have – no more dirty diapers and expense for diapers either! (An idea for an SF short story?)

     

 

After all their efforts, the parents are usually ready for those babies to fledge – the subject of the upcoming last blog in the series.

 

 

* Not all the photos in this blog are of great quality, I know, but my intention was first to show behaviors and secondarily to have some nice shots in the blog.

 

 

Birdie beauty – hummingbird preening and grooming

ruby-throated hummingbird DK7A6865© Maria de Bruyn res

ruby-throated hummingbird DK7A1226© Maria de Bruyn resIt has been great to welcome back the sun and dispel some of the gloom resulting from the record number of rainy days we’ve had. Watching the ruby-throated hummingbirds (Archilochus colubris) in my yard and at nature reserves is also a day brightener and has taught me that these tiny avians are quite fastidious, grooming often and at length.

 

 

They cannot use their feet to hop or walk; they only cling to perches and shuffle a bit.

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They do use their claws as a “comb” to groom their heads and necks and to scratch itches.

ruby-throated hummingbird DK7A7454© Maria de Bruyn resruby-throated hummingbird DK7A1811© Maria de Bruyn res

Using oil from a gland near their tail, they cover their iridescent feathers with the oil to help clean them.

ruby-throated hummingbird DK7A1112© Maria de Bruyn resruby-throated hummingbird DK7A1230© Maria de Bruyn res

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When you see them rubbing their long beaks on a twig, they are wiping off debris and pollen.

ruby-throated hummingbird DK7A7094© Maria de Bruyn res

The youngest birds have a groove in their beak but this smooths out by the winter.

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When the hummers look up in the sky, while sitting all puffed up on a branch, they may be taking a sun bath.

ruby-throated hummingbird DK7A7969© Maria de Bruyn res ruby-throated hummingbird DK7A7804© Maria de Bruyn res

A tiny catnap – or hummer nap – can also be observed now and then. This is understandable since their little hearts beat at 1220 times per minute while they fly; this lessens to about 250 times per minute when they are at rest.

ruby-throated hummingbird DK7A0060© Maria de Bruyn resruby-throated hummingbird DK7A7319© Maria de Bruyn res

ruby-throated hummingbird DK7A0389© Maria de Bruyn res

ruby-throated hummingbird DK7A7355© Maria de Bruyn res

 

 

You can sometimes tell the sex of the hummingbird by its tail feathers. The tips are white and rounded in both females and first-year males, who do not yet have fully colored throats

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ruby-throated hummingbird DK7A2031© Maria de Bruyn

 

In the adult males, the tail feathers have sharp black points.

The red gorget (throat) feathers that give this species its common name are seen in the adult males. Very occasionally, a female will have one or two black or one red feather there, but it is generally a young male that has one red throat feather.

ruby-throated hummingbird DK7A6577© Maria de Bruynruby-throated hummingbird DK7A0610© Maria de Bruyn res

ruby-throated hummingbird DK7A2084© Maria de Bruyn res

 

After nesting, females may look somewhat tattered and molt their feathers, like this one in July. The regular molting period is autumn through about March and that is when the juvenile males develop their their red throats.

 

 

Both female and male ruby-throated hummers have a small patch of white feathers behind their dark eyes.

ruby-throated hummingbird DK7A8123© Maria de Bruynruby-throated hummingbird DK7A2409© Maria de Bruyn res

One thing is for sure – all these little avians are beautiful to see and watch!

More information:

http://www.hummingbirdworld.com/h/behavior.htm