Thursday, 21 November 2013

Large numbers of Whiskered Terns in Gippsland

The Wiskered Tern (Chlidonias hybridus), aka Marsh Tern, is found in Africa, Europe, Asia and Australia. There are three sub species hybridus (Eurasia), delandi (Africa) and javanicus (Australia).
Adult Whiskered Tern in breeding plumage - note full black cap, red bill and legs and the dark grey under parts.
Adult bird - Whiskered Terns have a slight V in tail only visible when the tail is closed.
The name Whiskered Tern is derived from the white band seen here between the black cap and the grey under parts. Not a very obvious whisker in my opinion - I think I prefer the earlier name Marsh Tern.
The Whiskered Tern is widespread across Australia during the non breeding season and a rare vagrant to Tasmania. It breeds erratically according to seasonal conditions, but generally from September to December, in southeastern Australia. 
The Whiskered Tern frequents inland waters. It is not a marine species, however it can sometimes be found in estuaries and wetlands near the coast, such as the Gippsland Lakes, particularly the adjacent wetlands. A gregarious species, these terns feed, roost, travel and nest together, mostly in small flocks, however occasionally large flocks containing a thousand or more birds are encountered. They are certainly a nomadic species however some are thought to be migratory moving from the Top End to Indonesia and Asia and back again.
In East Gippsland, we see small parties of Whiskered Terns over our wetlands from time to time. This year we are seeing more flocks than normal and larger flocks. Conditions in East Gippsland are generally good this spring with plenty of water in our wetlands. Inland Australia is drying out following a run of wet years when many water birds took advantage of the favourable conditions to breed up. So perhaps it is not surprising that we are now seeing larger than normal numbers of Whiskered Terns in suitable near coastal habitats as many species head for the coast when inland Australia dries out.
I discovered a larger than normal flock of Whiskered Terns on Wednesday the 6th of November near Hollands Landing, a very small fishing hamlet on McLennans Straits at the western end of Lake Victoria. Returning from a Gippsland Lakes Important Bird Area (GLIBA) survey in the Sale area I decided to detour in to Hollands Landing to check out the birds there – it is a good location for water and shore birds, including migratory wader species.
From Bengworden Road, a back road between Sale and Bairnsdale, driving along Hollands Landing Road I came across a large number of white birds flying low over the flat sheep and cattle paddocks.  It soon became obvious they were Whiskered Terns, well over a 1,000 birds, and they were coursing low over the paddocks. From time to time birds would dive into the long grass. They were clearly feeding. For me this was odd as I had always seen them feeding over water in the past. Like all terns their diet consists mainly of small fish taken by diving into water. Checking some field guides and other reference books later I found that feeding over dry land was not mentioned so I assume this behavior is at least a little unusual.
The bird in the lower foreground has just caught an insect on the ground - see next shot.
Note the small food item in this bird's bill.
In this shot a bird's wings are just visible above the top of the long grass.
It was a marvelous spectacle to stand by the side of the road and watch such a large number of birds in action. In every direction I looked I could see terns over the adjacent paddocks. As they coursed around and back and forth over the paddocks, they alternated between dispersal to chase food and aggregating into strung out flocks. They seemed to randomly follow a leader for a short while and then the flocks would break up again and birds would spread out over a paddock and look for insects in the head down position typical of all terns.
A small section of the leading end of one of many groups in the area. The birds wheeled around and coursed back and forth before breaking up and dispersing over a paddock to hunt. At some undisclosed signal they would gather again to repeat the cycle. They are hard to count however there are nearly 90 birds in this shot alone with another 200 or 300 birds out of the image behind them. And this was only one of many similar sized groups in the area.
As I watched them and took the opportunity to take some photos now and again as random chance brought some of them close enough for photos, the landowner, out checking his stock on a motor bike, came over for a chat. He was interested to know what species of bird they were, as he had not seen them before. He said they had turned up two days earlier (the 4th).
The birds were still feeding over the same paddocks 14 days latter on the 18th of November when a group from Birdlife East Gippsland visited Hollands Landing as a regular Monday outing and to conduct three GLIBA surveys there. The farmer mentioned above has had a valuable service performed by these birds as a thousand birds or more must have converted a lot of pasture eating insects into fertiliser over the 14 days.
Many of the birds were in breeding plumage with black caps, red bills and feet and dark grey under parts. When in non-breeding condition the under parts are white, the forehead white and the bill and feet are blackish.
I wonder if these birds have recently bred or are going to breed? Perhaps the latter as there did not look to be any juvenile birds in the flock – it is not that easy to pick as adult birds in non-breeding plumage look similar to juveniles?
An adult in non-breeding plumage.
Another view of a non-breeding bird - note there is no black cap, just some blotchy patches of black feathers. And the under parts are mostly white though a little blotchy.

Thursday, 7 November 2013

Owlet-nightjar – a lucky find

This morning I was with a small group from BirdLife East Gippsland conducting a bird survey for the Gippsland Plains Catchment Management Network in woodland in the Forge Creek Water Reserve near Paynesville. Two in the group noticed a bird flush from somewhere near the ground and fly up into a tree above. Another member of the group spotted the bird in the tree, an Australian Owlet-nightjar.
The Australian Owlet-nightjar flushed during a bird survey in the Forge Creek Water Reserve today.
The whisker like feathers on the face stand out in this shot against the sky. Do these act like cat whiskers or sensors to protect the bird's eyes from injury from flying insects at night?
Note: The photos can be enlarged with a left mouse click and the mouse wheel can be used to scroll through the images as a slide show.  
These small nocturnal birds are widespread across the Australian mainland and also found in Tasmania. They are common in suitable habitat, especially woodlands, where there are suitable tree hollows in which to spend the day roosting. Also holes in embankments and cliff faces may be used. In winter they often sun themselves at the entrance of their roosting hole.
While these birds may be common it is far from common to see one. When they are seen it is mostly when they are found sunning themselves at a hollow entrance or when they are flushed, as the bird was today. Finding them at night with a light is almost impossible for unlike most nocturnal animals, which have large light reflecting eyes, Owlet-nightjars, while they do have large eyes, do not reflect torchlight at all. I was lucky enough to find one at night with a torch so I can testify from first hand experience that they have no eye shine at night.
Therefore the group’s excitement at finding this rarely seen bird today was understandable and the two photographers in the group took full advantage of the rare opportunity while the bird posed within camera range.
The bird flew a short distance to a new perch. Note raptor like claws. Does this bird catch prey at night on the wing in its beak or with its feet, or both?
In spite of its name the Owlet-nightjar is not related to Nightjars. The nearest relatives are thought to be swifts and while this may seem surprising I think they do have some similarities. Before I became aware of the relationship with swifts I saw an Owlet-nightjar at Gluepot in South Australia one night swooping a number of times by our camp site, chasing moths attracted by the light and I was left with the feeling that this bird looked like a swift. 
Other names used in the past for the Owlet-nightjar include Little Nightjar (as mentioned above they are not related to nightjars), Fairy Owl (they are not related to owls) and Moth Owl, a partly appropriate name as their diet does mainly consist of nocturnally active insects caught on the wing, including moths and beetles.
Looking out from a hollow this very cute face could look like a small possum such as a Sugar Glider.

Saturday, 2 November 2013

A cuckoo in the garden

An unmistakable birdcall alerted me to the presence of a cuckoo in our garden this morning. The call was a series of ascending notes, sometimes described as semi-tones, indeed this bird has been called the Semitone-bird or Scale-bird. The bird calling in our garden was of course a Pallid Cuckoo.
NOTE: Photos can be enlarged by left click of mouse on photo and then mouse wheel can be used to scroll through the photos as a slide show.
The adult male Pallid Cuckoo calling in the garden today. I have interrupted his calling.
Satisfied I am no threat he resumes his scales.
His energies were not completely focused on attracting a mate. He stopped calling to swoop down and grab a moth and then he moved to another tree to beat the moth a few time on a branch before swallowing it. Hairy caterpillars, grasshoppers, beetles and other insects make up the diet of Pallid Cuckoos.
The moth consumed he resumes calling.
The call, repeated over and over again, was coming from a male Pallid Cuckoo, a male because only the male makes the ascending call. The female, if and when she replies, only issues a single harsh note. Another name for this cuckoo is the Brainfever-bird, as it sometimes continues calling for long periods, including occasionally at night, which can drive some people mad, or at least it can become seriously annoying, especially if it is keeping you awake at night.
Another apt name for this species is Harbinger-of-Spring as it is a strong seasonal migrant to southeastern Australia where its return each Spring is announced loud and clear by the call.
The name cuckoo, applied to some 12 cuckoo species in Australia, derived from the cuckoo found in Europe, which makes a call sounding like “cuckoo”.  It is one of those onomatopoeic words where the sound of the word imitates the sound of the thing or action being described, as for example in the words hiss, buzz and bang.  In the case of the European Cuckoo the bird’s call is the sound “cuckoo”.  However in spite of bearing the name cuckoo not one Australian species makes a call that sounds anything like “cuckoo”.
Most Australian cuckoos, but not all, are nest parasites meaning they lay their eggs in the nest of another species leaving the unwitting hosts to raise their young. The Pallid Cuckoo is a “nest parasite” and some 50 species are potential hosts for Pallid Cuckoos with Yellow-faced Honeyeater being one of the most common victims, which is possibly not surprising given the Yellow-faced Honeyeater is also a strong seasonal migrant returning to southeastern Australia every Spring in large numbers to breed. 
Yellow-faced Honeyeaters are a common victim of the Pallid Cuckoo's nest parasitism. This bird has been having a bath.
The male Pallid Cuckoo is a grey bird with some brown hints. The female is a mottled rufous brown, a colour not needed for sitting camouflaged on a nest but very handy for sneaking in undetected to lay one egg in the nest of an unsuspecting pair of host birds while they are distracted by her mate. She removes one egg so the owners of the nest will not notice any change. When hatched the young cuckoo will eject the other eggs or hatchlings from the nest leaving only the cuckoo for the hosts to raise.
The male Pallid Cuckoo.
This is a juvenile or young male - note spots on wing covert margins. This photo was taken in Sturt National Park NW NSW.
The female Pallid Cuckoo - note the mottled brown and rufous colour. Photo taken on Wangarabell Road north of Genoa far East Gippsland.
The challenges of reproduction have seen many different methods evolved across various species to bring forth the next generation, however nest parasitism is one of the more fascinating solutions. 
The male Pallid Cuckoo called on and off in and around the garden throughout the day. I listened to see if a female answered his call. Just on dusk he was still calling when I heard a female respond with her one coarse note. Perhaps he did not call all day in vain?