Showing posts with label Nestlings. Show all posts
Showing posts with label Nestlings. Show all posts

Wednesday 3 December 2014

Superb Fairy-wrens in the garden


The adult male fairy-wren with a woodlouse
A pair of Superb Fairy-wrens Malurus cyaneus have just fledged a brood of chicks from a nest in our garden, outside our bedroom window. The nest was set under an old lavender bush, woven into the mesh of grasses and twigs. It was not much more than a see-through domed cradle for the eggs with the roof for concealment and a thin lining of fine grass and downy plant seed cases to support the eggs and then chicks.

The female creeps towards the nest, ever watchful for predators
The birds were accustomed to me and other people moving about the garden and carried on feeding the chicks while we were close, so I took the opportunity to capture a few images of these stunningly beautiful garden birds.

The large brood of four nestlings begging for food
I spent less than an hour watching the birds feed their youngsters and in that time they made fifteen trips to the nest, the male seven and the female eight times. They brought in a variety of items and I was surprised at the large size of some the prey, the grasshoppers and butterfly being the biggest.

The chicks were about ten days old and well feathered. They all fledged three days later and are now flitting around the garden following their parents in the ever busy search for food.

The male brings in a caterpillar
The female seemed to have the knack at catching flies for she brought in four during the watch.

The female brings in a fly
And she caught a tiny hoverfly.

Then a hoverfly - tricky to catch?
It was such a delightful experience to sit quietly next to the nest while the birds went about their business. Real live wildlife action in the garden. There is no need to travel thousands of miles to see spectacular animals, simply stop and take notice of what is going on all around us, even in the cities, there is something going on somewhere. Who knows what we'll witness next. Just take the chances when they come.

The male brought in two grasshoppers
I thought the male was specialising in the larger items, until the female brought in a blue butterfly, the perfect colour for such superbly blue birds.

A beautiful meal for one of the chicks

Thursday 2 October 2014

Grey Butcherbird

A Grey Butcherbird Cracticus torquatus arrives at its nest with food for its young
The bird breeding season around Canberra is a protracted affair, with some birds like the Wedge-tailed Eagles and Superb Lyrebirds laying their eggs in winter, as well as a few small birds such as, for example some Buff-rumped Thornbills. At the moment a White-browed Scrubwren is incubating eggs in a nest in our garden - due to hatch any day now. However, Spring is the main breeding season and for most species; whether building nests, laying eggs, incubating them, feeding nestlings or caring for fledglings, some part of their breeding programme usually occurs then. It simply makes sense, timing their offspring's fledging and dispersal into the population to fit the period of the year when most of their food is abundant. Depending on species, the birds' food can be flower nectar, fruit, insects or other smaller animals such as, well, young birds. And each species times its breeding period to fit their young fledging when their food is most abundant

I often find these birds in the woodlands when I am monitoring the Tawny Frogmouths,
and this pair were nesting in a small tree next to a Frogmouth nest tree
Insects are becoming more abundant every day as the weather warms up, although flying insects can be difficult to catch and often it is their larvae that are bigger and more nutritious than the adult forms, such as moth caterpillars. Butcherbirds catch most of their prey on the ground, like the big fat grub that this one caught.

All butcherbirds have hooked tips to their bills - for catching and holding prey efficiently
There is a reason for all bird behaviour and all bird anatomy. Evolution if driven by efficiency

But birds' bills are sensitive organs and the butcherbird thrust the food
deep into its chick's throat without the slightest bit of harm

Monday 16 June 2014

Precocial and Altricial young

Birds in Scotland are busy hatching and rearing their young at the moment, with June being the month when most species have dependent young at some age. I have been ringing, with other members of the Grampian Ringing Group, various species of chicks from common and tiny Willow Warblers to large and rare Golden Eagles, and all sorts between. While doing so, I have as ever been impressed by how well each species has adapted the best method of post-egg development to suit its lifestyle.
 
Common Gull eggs, with cracklines and holes - the chicks are beginning to hatch

I have been ringing gull and wader chicks and took a sequence of photographs at one Common Gull colony to show the development of their chicks. The typical clutch size is three eggs and the chicks hatch one after another, over about two days. The first chick to hatch stays in the next and are brooded by the adult birds until the last chick hatches and dries. Then they all begin to wander from the nest, usually set on the ground, and hide beneath the surrounding vegetation.

One dry chick, one wet chick and one still on its way out

Gull chicks have cryptically-coloured down which keeps them concealed from predators and warm. They can walk sand run strongly and are known as precocial young.

A fully dry Common Gull chick - two days old and now three metres from the nest

Or rather, gull chicks are better described as Semi-Precocial young, those which are downy and can walk and can leave the nest soon after hatching. e.g. in the case of terns and gulls, although they still rely on their parents for heat and nourishment.

True fully precocial, self-dependent young would be such as Mallee Fowl which find their own food without even guidance from either parent.

This is so different from the familiar nestling birds, which are Altricial - where the young are naked, blind, weak-limbed at hatch and rely totally on their parents for food and heat.

Semi-altricial young such as raptors are downy at hatch, but weak and rely on their parents for heat and food.

Four Skylark chicks in their nest











Two other terms which are used to describe young birds are; Nidifugous - those that leave the nest soon after hatching, generally once the whole brood has hatched and their down dried, and Nidicolous - those which remain in the nest for several days or weeks after hatching.

A three-day old Skylark chick, still partially naked and blind

The nestling stage is a very vulnerable period for young birds and the variety of concealment and protection methods taken by the parent birds is, to me even more fascinating. From secretive single nests to noisy colonies, each works for the protection of different species. But more on that later.

Five kestrel chicks - ranging from about one to two weeks old