Young birds - how to determine their age

A young Striated Pardalote, less than one year old

On the last trip to study birds at Charcoal Tank Nature Reserve, NSW, over the weekend of 15-16th March, which was run by Mark Clayton as usual, we caught a variety of young birds. This was not surprising as it was only a month or so after the main breeding period for most birds in the area had ended, but we caught 26 species amongst the 119 birds caught altogether, and determining the age of birds can be tricky. So to help illustrate just how these young birds were identified, I have set out below some examples of the various methods that can be used to establish their age.

A front-on view of the same young pardalote

Immature Plumage -  The main, quickly seen features which were followed to determine this Striated Pardalote Pardalotus striatus as a young bird were the beginnings of only a few streaks on the crown and no white eyebrow behind the yellow flash above the eye. This bird will gradually moult out its first young-bird feathers and grow true adult-coloured feathers during its first year of life, with a fully streaked crwon and a wide white eyebrow.

A young Double-barred Finch

Feather development - To the trained eye, this Double-barred Finch Taeniopygia bichenovii is likely a young bird as it has narrower black bands across its breast than an adult would have. But that is a relative criterion, which is not of much use if there is not an adult to compare it with. More precisely, it can be aged as a young bird, less than one year old, by the incomplete covering of underwing feathers. In the second image, the flesh and line of the bones can be clearly seen because they are not fully covered like those in an adult bird. The most important feathers for a young  bird to grow are its body feathers for warmth, then flight feathers for mobility. The sooner they can leave the nest, the easier it is for them to escape from predators. So they gradually complete their body plumage in the less exposed parts, such as under their wings, as they continue to develop into full-grown birds. 

The partially bare underwing of the same young Double-barred Finch

A young White-plumed Honeyeater - in its first year

Pigmentation - this can be costly for a young bird to lay down, nothing comes without cost, even in nature. So young White-plumed Honeyeaters Lichenostomus penicillatus concentrate their nutritional resources in growing a basic bill, enough to serve the purpose of feeding, preening etc.. There is no need for deep pigmentation. That is added slowly during its first year of life, and by the following breeding season it will have a fully black shiny bill, a sign of an adult bird in breeding plumage.

This first-year White-plumed Honeyeater is probably a few months old and has begun to grow a dark bill,
 starting from the tip

Young Sacred Kingfisher - less than one year old

Buff-tips - many young birds have buff-tips to some of their feathers, such as this young Sacred Kingfisher Todiramphus sanctus, which has such feathers in its wing coverts and crown. Most of these will be moulted out during the first year, and the bird will be in adult breeding plumage in time for the next season. Some other species can retain a small number of these buff-tipped feathers into their second year while they are breeding, but if a Sacred Kingfisher has lots of such feathers between breeding seasons, then it can be confidently classified as a first-year bird. 

A back-view of the same kingfisher - this bird has a broken tail feather, snapped along the line of a fault-bar. This is a weak part of the bird's tail feather which is a result of less keratin being laid down in the feather during a period of less nutrition intake as the young bird's tail grew

A young rainbow Bee-eater

Ornamental feathers - or lack of.  Some species of birds grow elaborate ornamental feathers as part of their adult breeding plumage, like the Rainbow Bee-eater Merops ornatus which have extended central tail-feather streamers. The young birds however, do not grow these. To grow such feathers for no purpose in their first year, as they are only required for breeding display, would be an excessive waste of nutrition. 

Gang-gang Cockatoo Survey

An adult male gang-gang inspects a potential nest hollow

Today saw the launch of the Canberra Ornithologists Group's Gang-gang Cockatoo survey. The survey organiser, Chris Davey introduced the project to a group of birders at Corroboree Park, then naturalist Ian Fraser added a few details and anecdotes to inspire people to go out, find the birds and log their results in the online survey - http://canberrabirds.org.au/observing-birds/gang-gang-survey/. All records of Gang-gangs in the ACT and surrounding district are welcome, including negative ones, and there are already hundreds entered. The project runs for eighteen months to cover all seasons fully and we hope to have a clearer picture of where the birds breed, overwinter, and what habitats need to be preserved if the birds are to be here in the future. So if any one in the area can add information to the survey please do, it's easy, and rewarding. 

I was involved in the design and production of the survey brochure, a fold-out introduction to the bird and project. See below.

Huge deposits of pumice on the beaches

Piles of pebbles of pumice lie on the tide-line along the new South wales south coast

The sandy beaches and hidden coves of the New South Wales south coast are presently littered with pumice pebbles. They have come from 4000 km out in the Pacific Ocean, north of New Zealand, where a submarine volcano on the Havre Seamount, near the Kermadec Islands erupted last July. This caused a raft of pumice covering 20,000 sq km to form and gradually drift west on the currents. When they reached the Australian coast they were washed up and concentrated on the tide-line. 

The pumice formed as lava erupted under water and air trapped in tiny pockets in the rock makes the it buoyant. This was the largest such eruption in the region for over fifty years. There were all sorts of plant and animal life attached to some of the larger and rougher pieces, and I wonder what land-based life will find a niche in the new rocky tide-line. 

The pumice is light and floats like the bladders of the seaweeds which it lies with on the shore

Most of the pebbles are small, but some are as large or larger than a cricket ball

The pumice floated from north of new Zealand to the south east coast of Australia

A few art lessons from Melbourne

Add your name if this is your work, I don't want the credit, just spread the word
Street art on Hosier Lane 14th February 2014

It has been a hot few weeks in Melbourne and I was down to look around some Tawny Frogmouth sites with Marian Weaving who is studying them there, out in suburbia. Then once I did that I went into town to look up the recent artwork. The collections in the galleries were as good as ever, but there were great environmental messages going on out on the streets, especially in and around Federation Square.

In the middle of the square is a triptych sculpture of Dogman and Rabbitgirl riding a rhino, the creations of artists Gillie and Marc. I am familiar with their work, and it is good to see this plea to help save rhinos in such a high profile.

Rabbitgirl and Dogman ride a rhino for life

Thousands of people pass through the square every week, day? Many took photos of themselves in front of the sculpture, but unfortunately very few took the time to read the message. I know, I watched them. Most were tourists from around the world; what apathy from people who profess to enjoy the planet.

Thanks for the message Gillie and Marc

Impressive art for an impressive animal

Meanwhile over on the pavement across from Flinders Street Station, Chris Jordan had built a sculpture of a mobile phone with old mobile phones about to be re-cycled. He was in town to add his voice and skills to the Sustainable Living Festival, to see more on that click this.

A mobile phone made with mobile phones

Re-cycle your old phones!

Chris was giving a talk in the Deakin Edge theatre on various topics concerning our waste and the damage we cause to other animals on the planet. Part of his presentation included a viewing of his powerful video on the effect plastic is having on albatrosses  This was uploaded on line two years ago now, but the message is still the same. If you haven't seen this and would like to watch it, click here, but be warned it is sad, very sad.

More on aging and sexing Rufous Whistlers

Following some interesting feedback on the previous piece on aging and sexing Rufous Whistlers Pachycephala rufiventris, I have added a few more examples of details to look for when doing so.

Adult female Rufous Whistler
Charcoal Tank, NSW, Oct 2010

This first adult female (3+) shows the features of a dark red eye, dark black bill, white throat streaked with dark grey and streaked breast.

Left - Adult female, right Immature (unsexed)
Charcoal tank, NSW, Oct 2010

The shot above shows a second adult female (3+) alongside an immature, unsexed bird (2). Her eye is clearly red compared with the young bird's brown eyes. Her head is grey streaked with black, her belly is pale buff, almost white, and she has very little streaking on her undertail coverts. In comparison, the young bird has a grey/buff head with finer black streaks, its belly is a creamy orange and there is definite streaking on the undertail coverts. The immature bird would have hatched in the Spring two years previous to that when the shot was taken, but as it was still early in the breeding season when the bird was caught, October, and as sub-adult males can breed in their second year while in such a plumage, the bird cannot be sexed. It might yet moult into sub-adult male plumage later in or after the breeding period.

The photograph below shows the heads in profile of the same two birds. Note the female's grey head versus the young bird's brownish colour. Her iris is red, the other bird's is brown. Her bill is black on the outside upper and lower mandibles, and inside. The young bird's bill is dark, almost black on the upper mandible, brownish grey on the lower, and with a pale yellow inside the roof. Also her bill is worn with use, with chips and flecks taken out of it, while the young bird's bill is smooth edged and clean-looking with pale margins.

Left - Adult female, right Immature (unsexed)
Charcoal Tank, Oct 2010

In comparison of the two adult birds, the second adult female has a brighter shade of red in her eye, her breast is less rufous, her belly is paler, and her undertail coverts are less streaked. This might simply be normal variation in colouring between individual birds. However, she might be an older bird, so further study needs to be done on the features listed here on re trapped birds of known age, to help clarify this point.