Sunday, 26 April 2015

Tawny Frogmouths in their winter roosts

A Tawny Frogmouth roost-tree in open woodland
It's now late autumn and migrant birds such as the yellow-faced honeyeaters are flying over the house and general area on their annual migration to the northern and coastal forests. While other birds like the tawny frogmouths are settling down in the local woods for the winter. The frogmouths stay in their breeding territories over the winter, probably because they are a valuable resource and worth defending. And in the bird world, occupiers usually win over any intruder. So to keep warm in the cooler months, during the day they settle on a favourite perch where they can catch the winter sun.

A Tawny Frogmouth sits quietly in her roost

I know most of the local birds' perches and  most days they will be in one of perhaps two or three, for they have sussed that those branches offer shelter from predators and exposure to the sun. Exposure to the sun is important to them, for the morning sun warms them up. Also, these birds can go into torpor for part of the day to conserve energy. And that is not their only two strategies for enduring the winter, they also build up body fat. The female I found dead last week was carrying 88 grams of fat, approximately 16% of her weight, and her stomach was full of beetles and large moths. The contents formed 8% of her weight. She had been feeding hard catching the last of the autumn insects before the lean times ahead in the cold nights. (I acknowledge Gil Pfitzner of CSIRO for this information as he was the one who prepared her skin for the national collection and took these measurements).

This bird is several years old - I know her by the pattern of her bib,
and she knows me because she has seen me so often over the years
The more we look at birds, or any other wildlife, the more we can learn about how well adapted each species is for its own niche. As for the tawny frogmouths, they have so many adaptations, they continue to fascinate me. No doubt they will have more that I don't know of - just what is the purpose of those bristles above their eyes and bill?

Here she has closed her eyelids, almost. She is still peeping through a slit and even if she closed her eyes further, she could watch me through tiny gaps between her eyelids. For her eyelids have rippled edges allowing her to see out, but not for a predator to see her eyes. Frogmouths are very well adapted for concealment, right down to their eyelids, and surveillance at the same time. Eyes can be a big betrayer of camouflage. This bird hasn't gone into full defensive pose as she is familiar with me and does not feel under threat. She is just basking in the sun - with a little caution.

Friday, 17 April 2015

A true Tawny Frogmouth

A truly red/rufous coloured Tawny Frogmouth found in Canberra - a victim of road kill
It was wet with heavy rain last night, and all day today, and when I drove into town in the morning I saw a dead bird lying in the cycle lane. It looked like a Boobook, the common local owl in Canberra, but it didn't look right for one. So I took note of where it was in order to check it on my return. Maybe it was something else, what? Then an hour later, as I approached the bird from the other direction, I saw straight away that it was a Tawny Frogmouth, but it was so red, and that is why I hadn't recognised it first time. Although I study these birds and have seen hundreds of individuals, none have been as red as this bird.

All the frogmouths I have seen in the Canberra area have, despite their name, been predominately grey. The males have, if any, only a little red on the sides of their face or a touch on their wings coverts. The females are usually more rufous in the same parts, and a few have a bit more red on their wings, but none I have seen have been so red as this bird. I would so much have liked to have met her when alive in the bush.

The whole of her upper body was red
 apart from her primary and secondary feathers which were dark brown/black
The bird's body was in good condition apart form the obvious head injury that killed her outright. So I gathered her up and took a few measurements for my own records. Her corpse is now in the freezer and on Monday I shall deliver her to the Australian National Wildlife Collection, which is conveniently held by CSIRO here in Canberra, the national capital.

I must look up the type-specimen of Tawny Frogmouth one day to see whether that bird was truly tawny, or grey like most in south-east Australia.

She still had a recently caught moth in her bill when she died
The moth was large, with a body about 8-9 cm long, and grey overall with no particularly obvious features. If anyone has an idea of what it might have been please drop a note. It was obviously too large a prize for the bird to ignore as she risked the traffic to catch it. Let that be lesson to us all: take care on the roads especially while there is heavy rain.

Tuesday, 14 April 2015

Mixed Foraging Flock

A Buff-rumped Thornbill: they glean food from the lower branches, trunks and ground litter

Now that autumn is well on the way here in Canberra, the woodland passerines are gathering into their mixed foraging flocks. These flocks are similar to those in northern-hemisphere woodlands where several species; such as coal tits, blue tits, great tits, goldcrests and treecreepers all join together and roam through a local patch of woodland. In and around Canberra, a typical mix of species would be like one I saw yesterday which consisted of; several buff-rumped thornbills, several yellow-rumped thornbills, perhaps ten grey fantails, I think three white-throated treecreepers, a family party of superb fairy-wrens, two scarlet robins, a pair of speckled warblers and a grey shrike-thrush.

A Yellow-rumped Thornbill: they flit down to the ground for their food

These mixed flocks are an efficient strategy for the birds to collect food within the safety of their group. Many eyes are better than one for locating food and for detecting any approach of potential predators. And each species has its own preferred type of food or place to gather it from. The buff-rumped thornbills pick away at the bark for insects beneath and they might not catch every insect they disturb. Then the fantails might zip in and snatch a insect trying to escape, or a speckled warbler following along on the ground can pick up any grubs that the thornbills dislodge. The yellow-rumped thornbills keep in their own flock within the mixed flock, dropping to forage on the ground then flying back up to the lower branches after a quick feed. The superb fairy-wrens probably only joined the party as the flock moved through their home patch, taking the advantage of the group foraging behaviour while they could.

A Grey Fantail: they fly-catch tiny insects, often those disturbed by the other birds in the flock

Two male Scarlet Robins dispute in the branches
Within each mixed foraging flock there are usually two scarlet robins, one male and one female. They seem to adopt the flock as their winter/non-breeding season territory and they defend it from all other scarlet robins. Yesterday I watched two such male robins displaying and threatening one another in such a dispute for ownership. The resource of a mixed foraging flock, with its advantages for survival, is clearly a valuable commodity for woodland birds.

That mixed flock seemed to consist of mainly lower branch- or ground-feeding birds. I saw another two like that later and one flock which was formed mostly of striated thornbills and striated pardalotes, working their way through the canopy, picking food from the leaves and twigs, never venturing near the ground. Each bird in each flock will know their local patch of the woodland and together, they will work their way through the habitat every day of autumn and the oncoming winter.

Then in spring, they will disband and settle into pairs on breeding territories.

Sunday, 5 April 2015

Easter Bunny Hare

It's Easter and the Easter Bunny is hiding chocolate eggs all over gardens, or is he she? 

A White Hare - well almost white, in late winter / early spring pelage
The Easter Bunny is a modern spin on an ancient game originally played by children (and their parents) in Germany. The children would build little nests for the Oschter Haws - the Easter Hare - to come during the night and lay fancifully decorated eggs, a bit like Santa Claus coming at Christmas. This all developed from the pagan festival Ostara; celebrating the spring equinox, the Goddess Eostre and the arrival of fresh growth and new life. And as hares are obvious in springtime, they would have been a clear choice for a symbol of new life. Not rabbits, as they are a Mediterranean species and would have been unknown to people in the distant past in what is now Germany.

The bunny took over the role following the American adoption of the tradition, along with the chocolate eggs. As to why the bunny is white, the Oschter Haws is supposed to be white, but I don't know if anyone has ever seen him to verify that. Why is the bunny male anyway, shouldn't it be a female if it delivers eggs and is a symbol of new life?

I don't have a photograph of a white rabbit, nor a white phase Brown Hare, which I think the Oschter Haws is? So here I have added a shot of a white Mountain Hare, and a set of triplets I found last spring in the Scottish Highlands. A true sign of Spring and the fresh beginning to a year.

Happy Ostara to you all.

Three mountain leverets lying in one form, most unusual as they are usually kept separate for protection from predators

Leverets lie still, but ever watchful and ready to bolt to safety if threatened