Wednesday, 19 July 2017

Powerful Owl portraits

The Powerful Owl (Ninox strenua) is Australia’s largest owl with the Rufous Owl (Ninox rufa) coming a very close second in size. Now and again Powerful Owls can be found perched in a day-time roost in a shady tree and often they are clutching prey taken the night before.  

Please click on photos to enlarge.

Powerful Owl at a typical day time roost- a bare near-horizontal branch close to the trunk of the tree for perching and a Boobialla tree providing screening and shade.

Powerful Owls will often allow reasonably close approach when found in day-time roosts however they will flush if approached too closely, which I have done inadvertently on a couple of occasions.

The following portraits and cropped detailed shots were taken of the owl in the above photo using a 500mm prime lens which required the camera to be a good distance from the owl in order to fit the subject into the (full frame) camera frame.

The classic full frontal Powerful Owl portrait with piercing yellow/orange eyes instantly drawing our attention. The pupils are partly dilated in the shady roost location.

Unlike human eyes that swivel in their sockets owl eyes are fixed, so to look at something directly, owls must move their heads and face the object of their attention.

This head side-on photo was possible because the owl is looking to its right at another photographer.
Close to a full side-on head profile which shows the rictal bristles well. The sharply pointed hooked bill used for ripping flesh is also apparent.

Many bird species have rictal bristles including owls. However the purpose of these bristles is not clear. One function proposed for these bristles is sensory. For nocturnal birds such as owls, the bristles may help detect sound. My thought is the bristles may help protect the eyes. For a night flying bird the risk of hitting something like fine leaves is high and the consequences of eye damage is serious so perhaps the rictal bristles when encountering any foreign object cause the eyes to automatically close. This of course is pure speculation on my part.

The following photo is a cropped detail showing the feet and talons of the bird’s left foot on which it is perched – the other foot is tucked up almost out of sight under the belly feathers.



Only two of the bird’s four toes are visible with the other two obviously facing backwards. When in flight and sometimes when perching, three toes are held forward. Mostly when perching and when clutching prey the outer toe swivels backwards leaving only two toes facing forward. Also visible in the cropped foot detail are the long sharp lethal talons and the rough textured soles of the feet which helps the bird grasp prey. The feet are yellow however I am sure there are traces of blood visible on the feet.

You can find more on owl physiology here: http://www.owlpages.com/owls/articles.php?a=9

Once the two other photographers left the owl looked steadfastly straight ahead. Fortunately for me this was in the only direction that allowed a clear view of the bird.

For most birds their facial expressions are fairly fixed however owls with their forward-facing eyes can show a surprising variety of expressions, for example the wise-owl look. However the expressions we see are our own anthropocentric creations and should not be used to read anything into how the bird is feeling or what is it thinking. That said here are a few portraits showing various facial poses.  









Of course, being daytime it was the owl’s sleep time so as I stood quietly the owl’s eyes began to droop indicating the owl was not too troubled by my presence.





Each time I took a photo the owl’s eyes opened when it heard the camera shutter release. My camera clock indicated I had been with the bird for about 20 minutes, it was time to leave it in peace, so I departed, thankful for the opportunity to take some photos of the magnificent Powerful Owl.

Sunday, 16 July 2017

Hooded Plovers

This post has been inspired by a flock of seventeen Hooded Plovers found recently on the beach at Sailors Grave, East Cape, in the Cape Conran Coastal Park.

Hooded Plovers are strikingly beautiful birds.

Please click on photos to enlarge.

Adult Hooded Plover – the sexes are similar.

Hooded Plovers (Thinornis cuculattus – see note at the end of the post) are an Australian endemic shorebird which live on sandy beaches and estuary entrances, places we humans like to use for recreation. Being beach nesting birds they are especially vulnerable to disturbance when breeding. Therefore, given the increasing human population and our use of beaches, plus the presence of introduced predators such as feral foxes, Hooded plovers are now in decline and a threatened species. Also, climate change and rising sea levels are changing sandy beach profiles and increasing storm surge which is also impacting on breeding and food resources for the Hoodies.

During the breeding season Hooded Plover pairs occupy and vigorously defend breeding territories on suitable sandy beaches. So, during the breeding season from August through to January, we mostly see pairs or small family groups (two adults with between one and three young).

Hooded Plovers are mostly sedentary, however outside of the breeding season they can sometimes form flocks, suggesting they do move at least short distances in order to congregate. We recently found a small flock of seven birds at the Yerrung River mouth and a few days later, on the beach at East Cape Conran, we found seventeen birds feeding together. The largest flock reported by locals in the past was a flock of 27 Hoodies on the Snowy River estuary. Apparently the south-west WA sub-species, the Western Hooded Plover (Thinornis cuculattus tregallasi), has been recorded in flocks of 100 birds or more.

A flock of 17 Hooded Plovers feeding together on the beach at Sailors Grave East Cape Conran.

In South-East Australia we find the Eastern Hooded Plover (Thinornis cuculattus cuculattus) which has been separated from the Western Hooded Plover by the Great Australian Bight. This is no place for sand loving Hoodies where the Southern Ocean crashes into the 100 kilometre long Bunda Cliffs - http://headofbight.com.au/things-to-do/bunda-cliffs

The two gene pools have varied slightly since separation with the Western Hooded Plovers having a more extensive black mantle and unlike the strictly coastal eastern birds, the western birds can be found on inland salt lakes where they can also breed.   

We enjoyed observing the plovers and taking photos as they foraged in the surf zone and some bathed and preened.

The seventeen Hoodies comprised 12 adults and five sub adults raised during the previous breeding season ranging from birds in juvenile plumage that fledged in February or March 2017 and others approaching full adult plumage with streaky heads that were possibly 7 to 8 months old.

One of the older immature Hooded Plovers.
This bird is younger than the one above judging by the amount of black on the head.
This is an even younger bird with a lot fewer black head feathers.
This is a juvenile with no black feather development at all – it must have fledged in February or March 2017 towards the end of the last breeding season.
There were two very young birds – I am not sure if this is the same bird as the one in the last photo above or the other very young one.
A comparison photo showing the very young bird on the right and a slightly older bird.

By observing Hooded plovers in the months following the breeding season we can see how successful the breeding season has been. For the flock at Conran we can never know if the 12 adult birds formed 6 breeding pairs or which adults raised which young however on average we can say the 12 adults and potentially 6 pairs of birds have raised 5 young to a point where they are secure and self-sufficient. A success rate of 0.83 young per pair. However, if we assume that at least 2 of the adult birds did not breed then 5 pairs raised 1.0 chicks each.

Given Hooded Plovers lay between 2 and 3 eggs, one successfully raised young per breeding pair does not sound like a good outcome, however life for eggs and unfledged young on an ocean beach is tough and the attrition rate is high. So 0.83 - 1.0 is probably a great result! Though we do need to keep in mind the Conran birds live in relatively good habitat with much lower human impacts than say birds on the coast nearer to Melbourne. Also the local area has long been baited for foxes as part of the Southern Ark Project which is also a big plus for breeding Hoodies.

One of the adult birds had a strangely shaped head which was not due to feathers but an underlying growth or skull deformity.

An adult Hooded Plover with oddly shaped head.
The bulge on the head may be due to a recent growth or a birth defect?

The above photo clearly shows the black mantle - it is larger than when seen in profile and as shown in bird guides. The Australian Bird Guide (Menkhorst et al) shows the Western Hooded Plovers with its extensive black mantle.

The Hoodies were mostly feeding along the zone where the sea washed in and out, which was well down the beach as it was near to low tide when we were there. We did see seven of these birds briefly feeding at the upper limit of the sandy beach in the shade of Coastal Banksia – many small holes in the sand showed there was plenty of food in this location.

The following four photos shows an adult Hooded Plover extracting and eating a sand worm.

A Hooded Plover plunges its bill into the wet sand.
A sand worm is drawn out.
The tasty morsel is being swallowed.

The worm is almost gone. 
Having downed the worm the bird searches for another.

Some of the Hoodies interrupted their feeding for a bath.

Juvenile Hoodie bathing.
A quick flap of the wings to remove water.

The bath is followed by preening.
Following their bath they gave vigorous wing beats to shake off the water.
One bird is bathing and another is shaking water off its wings.

Hooded Plovers are sedentary with some local movements outside of the breeding season. However, some birds may move further as evidenced by one adult bird among the seventeen at Cape Conran which had a black flag marked W0.

Adult Hooded Plover with flag W0.

The black flag indicated this was a NSW bird which was duly confirmed by Amy Harris, Shorebird Recovery Coordinator with the NSW National Parks and Wildlife Service based in Narooma. Here is what Amy said:

“W0 is a female on the move! She was banded with her siblings at Nullica (a beach near Eden) on the 23/10/15 at 4 weeks age. So she has moved approximately 165km south. Thanks for the sighting – that is awesome to hear where she is.”

So W0 is a female aged about 1 year and 10 months old from the south coast of NSW. With a flag and subsequent sighting report we have added to the store of Hooded Plover knowledge which is particularly important for a threatened species.

It was a great joy and privilege in a beautiful setting on a sunny winter’s day to watch seventeen Hoodies going about their business of living. However I could not avoid the thought of their vulnerability and the threats they face. On a positive note however the BirdLife Australia Beach Nesting Birds Project -  http://birdlife.org.au/projects/beach-nesting-birds - is providing a helping hand to ensure Hoodies survive. We owe the BNB project staff and volunteers a debt of gratitude for the work they do.





Note:

The taxonomy of Australian birds is undergoing considerable change.

The scientific names quoted in this post are from BirdLife Australia Working List V2 (1).

Hooded Plover
Thinornis cucullatus
Eastern Hooded Plover
Thinornis cucullatus cucullatus
Western Hooded Plover
Thinornis cucullatus tregellasi

Previously, as per the BirdLife Australia Working List V1.1, the species name for the Hooded plover was rubricollis.

Hooded Plover
Thinornis rubricollis
Eastern Hooded Plover
Thinornis rubricollis rubricollis
Western Hooded Plover
Thinornis rubricollis tregellasi

For more information about bird names and taxonomy see the BirdLife website here:

As a guide to the names of Australian birds, both common and scientific, the BirdLife working list V2 is recommended.

I note the recently published “The Australian Bird Guide Menkhorst et al” has mainly used the International Ornithological Congress IOC V5.4 (Gill and Donsker 2015) taxonomic list which gives the Hooded Plover species name as cucullatus. Other earlier guides have used versions of Christidis and Boles 2008 which use the species name rubricollis.

The taxonomy and naming of Australian Birds is an interesting subject and fundamental to understanding our birds, their histories and relationships. If you have a copy of the new Menkhhorst et al guide I highly recommend reading the essay “A guide for birders to the evolution and classification of Australian birds” by Dr Leo Joseph, Australian National Wildlife Collection, CSIRO.


Also recommended is Australian Bird Names, A Complete Guide, by Ian Fraser and Jeannie Gray.

Wednesday, 12 July 2017

Miscellaneous photos from June and July 2017

Some photos taken over June and July that were not relevant to recent posts have accumulated so thought I would include them in this post of miscellaneous birds.

The photos are in chronological order with species name and location, and for some photos, brief notes.

Please click on photos to enlarge.

Grey Currawong Banksia Peninsula Gippsland Lakes.

Immature Australian Magpie Newlands Arm Gippsland Lakes.
The immature Magpie kept close company with this adult which may be a parent – it carried its tail up which is unusual and possibly due to an injury?

I couldn’t resist photographing this male Golden Whistler – Newlands Arm Gippsland Lakes.
Male Chestnut Teal - Newlands Arm Gippsland Lakes.
Female Chestnut Teal – partner to above male.

The above pair dabbling.
Azure Kingfisher - Jones Bay Gippsland Lakes.
Ditto above.

Bell Miner fluffed up against a very cold morning – Canni Creek Racecourse reserve near Buchan.
White-eared Honeyeater Canni Creek Racecourse.
Laughing Kookaburra fluffed up on a very cold morning - Buchan Caves Reserve.
Male Scarlet Robin a familiar winter bird when they leave the forests for more open habitat - Clifton Creek area near Bairnsdale.
Female Scarlet Robin – partner of the male above.
Nankeen Kestrel hovering and near motionless in strong wind currents above the West Cape Conran boat ramp, searching for prey.
The same bird as above, a male (note grey tail with sub terminal black band), has dived on a prey item but in this case, rises empty taloned.
The Kestrel resumes the hunt.
The beautifully patterned Bassian Thrush searches the leaf litter for food on the edge of the Marlo Bushland Reserve.
The Thrush, a ground feeder, spends a lot of time in dense low light habitat, hence the largish eyes.
This strongly back lit Crested Shrike-tit was borderline for inclusion in this post however as they are such a rare find I compromised on quality.  
Pacific Gull looking for food above the West Cape Conran boat ramp – dark blue sea horizon at the bottom of the photo.
The Snowy River Estuary resident vagrant, way out of normal range Beach Stone-curlew out chasing food along the shoreline in late afternoon light opposite Mots Beach just east of Marlo. This widely reported and twitched celebrity bird has been in residence for a couple of years now.

Hope you have enjoyed these miscellaneous bird photos.