Monday, July 22, 2013

Point Nepean

The Eastern Osprey (Pandion cristatus) is a very uncommon bird in Victoria so when three were seen at Point Nepean, south of Melbourne, we had to go.

The weather had been bad for days with rain and strong wind and I nearly decided that standing on a rocky ocean cliff looking for birds in those conditions was not a good idea. Thankfully Joy reminded me that Birding is an Extreme Sport so off we went. As it turned out the day was beautiful. The sun came out, the wind dropped to the point where the birds had good uplift along the cliffs and there was a nice surf running.

Access to Point Nepean has been impossible until just a few years ago. The area used to be an officer training school for the army and, many years ago, a quarantine station. Concrete gun emplacements were built back in the 1880s and maintained until the 1940s. These are now either in ruins or have been restored and opened to the public and are well worth looking at.

Point Nepean would be an excellent place to cliff watch for albatross, shearwaters, prions and other ocean birds but it is a 2.6 km walk from the car park, a long way to carry a scope and tripod. There is a regular shuttle bus but the fare is $10 for the day.

View west across The Rip to Point Lonsdale. Port Phillip Bay is to the right and Tasmania to the left.  Many birds feed in the waters of The Rip and the Ospreys seem to have joined them.

Looking east. An old gun emplacement can be seen. The round, rocky outcrop seemed to be the eastern limit for the Ospreys.


Gannets were flying right over our heads

... and they came very close as they headed out to sea

A pair of Sooty Oystercatchers complete with tracks, shadows and reflections

All images & text © Jenny Spry

Friday, July 12, 2013

Random Raptors at WTP

There has been a “blocking high” sitting over south-eastern Australia for just on a week now. Every morning has been clear and cold enough that ice forms on the windscreen of the car and ones breath rises white into the morning air. The normal cold west to south-west winds of winter are flowing south of Victoria and battering Tasmania. These calm, blue-sky conditions just scream for a person to go birding.

Down at Werribee the day is perfect. In spring and summer the place is shimmering with waders but now all that are around are a few Red-necked Stints, a couple of Greenshanks, and a hundred or so Double-banded Plover wintering over from New Zealand. Some surprises do exist though, like finding a lone Sharp-tailed Sandpiper in full breeding plumage and seven Bar-tailed Godwits on the sand flats at low tide. They shouldn’t be here; they should be in Siberia somewhere.

Wader watching requires hours of scanning mud flats and ones eyes are looking down and out. And the frustration, oh the frustration; could that be a Little Stint? Or over there, is that a Broad-billed? Damn!, that kite just flushed the flock, I am sure that was a mega White-rumped Sandpiper I saw just before they flew!

Right now though, in the middle of winter, all the action is in the air. Raptors are everywhere. On a good day 12 or 13 species can be seen and when the sky is azure blue and there is no wind, as it was last Tuesday, they are a sublime joy to watch. The small raptors hunt mice and small birds, the larger ones hunt ducks and larger birds, and the Black Falcon and Peregrine Falcon hunt what ever they want, or steal from the unwary.

Picture a Peregrine Falcon coming in low and fast across the green bank of a pond, over the calm blue water, no more than a metre from the surface, and into a flock of Pink-eared Ducks that are floating half asleep near the far bank. Pink-ears explode in all directions trying to escape, and the Peregrine banks and turns for another pass. Is it hunting or just having fun by scaring the ducks stupid? It is sometimes hard to tell.

Whistling Kites have a different strategy and again, Pink-eared Ducks are often the quarry. The kites also come in low using the bank of a pond for cover but their strategy is to keep one Pink-ear from getting off the water. Once they have trapped their target they hover over it and attack, forcing the duck to dive, and dive again until it is either drowned or is too exhausted to escape. At this point talons find the duck and it is carried to the bank and its death.

The Black Falcon is an opportunistic hunter. They are sleek and fast in flight and are as happy to strike down an unsuspecting bird as to steal the prey from another raptor such as a Black-shouldered Kite. A pair of Black Falcon were hunting over the Little River and took on a pair of Black-shouldered Kite. It was all over in seconds as the falcon came down on the perched kites. The kites rose up, and one was harassed by the falcon, dropped its prey (a small bird or rodent from the look), and the falcon caught it and sped off with the kites in futile, complaining pursuit. It was a spectacular display of aerial combat. It was one of those moments that make birding special; one of those moments when you just stand awed at what you have just seen. And months and years after you will pass this point and remember the blue sky, the agile attack and say “I once saw a Black Falcon attack a Black-shouldered kite, right here” and the moment will be relived, again, and again – ah, the joy of birding.

Werribee Raptors:

Australian Hobby

Peregrine Falcon hunting Pink-eared Ducks

White-bellied Sea-eagle

Wedge-tailed Eagle

Spotted Harrier warming in the early morning sun

Spotted Harrier, head on

Swamp Harrier hunting over grassland

Whistling Kite

Whistling Kite attempting to keep a Pink-eared Duck under water

Whistling Kite finishing its dinner

Light phase Brown Falcon

Dark phase Brown Falcon

Black Falcon with a meal stolen from a Black-shouldered Kite

The Black-shouldered Kite who lost its dinner to the Falcon

Nankeen Kestrel

All text and images © Jenny Spry

Monday, July 8, 2013

Welcome Swallows again

After my posting last week I got some replies about Welcome Swallows taking prey from below the surface of water. One email was from Mandy King in Warrnambool who sent me photos of swallows feeding in this manner. They were taking prey from a pool in an ephemeral wetland just west of Warrnambool. The photos were taken in the first week of August 2007.
Habitat photo showing clear water and flock of Welcome Swallows hunting and feeding (Mandy King)

Bird centre left is attacking prey and the rest are hovering in wait  (Mandy King)

Bird waiting to attack (Mandy King)

Brian Johnston sent me photos of swallows feeding from the same pool I saw them in at the WTP, Werribee. His photos were taken on 30th June 2012 and mine on 17 July 2012. This means that a food source of insect larvae was available from the pool for more than 2 weeks and that the swallows were feeding on it for at least that long.
Bird capturing prey (Brian Johnston)

Bird with prey doing "head swinging" motion. The prey is clearly visible in the beak (Brian Johnston)

Brian’s photos show the swallow using the same head swinging movement as seen in my photo. Brian suggested that this swing of the head, of nearly 180º, is part of the food capture movement and I agree it may be a method of quickly getting the prey clear of the water. It may also be a method of clearing water from the mouth, or both suggestions may be correct.

What is not know yet is how far the head swing goes. My photo shows the head about 170º to the left (below) while Brian's shows it at about 170º to the right. The question is; after a larvae is captured, is the head swung randomly as to left or right, or does the bird do a full 340º +/- swing of the head? 
Head swung to left (Jenny Spry)

I now have four reports from late June to early August. Two reports are from 2007 and two from 2012. As it is early July swallows should now be feeding in this manner along the Victorian coast, and perhaps elsewhere. Please keep a watch on flocks of swallows in your local patch, and elsewhere.

Brian also has a photo of a Welcome Swallow coming out of the "tail stand luring" position that I mentioned in my blog of swallows using the attenuated tail feathers during hunting.
Swallow moving from "tail stand luring" position to attack (B Johnston)

All text and photos © to authors

Tuesday, July 2, 2013

Welcome Swallow luring prey with attenuated outer tail feathers?

An observation of the same Welcome Swallows mentioned in the sub-surface feeding blog was that, while feeding on prey taken from below the water surface, the birds were often seen to adopt a pose that appeared to be used to lure prey to the surface. It cannot be proved that the swallows were attempting to lure prey but it would be worth further study if similar feeding events are witnessed.

The swallows moved from a near horizontal hovering position to a near vertical hovering position and peered at the water. In this raised position they would then lower to touch the tip of the attenuated outer tail feathers to the water, creating a ripple, then raise up and repeat the tail touch action, or alternatively return to a horizontal position whilst still watching the water surface intently. On some occasions the bird would drop and attack near where the tail had been touching, and other times the bird would rise and turn back without attacking.

The birds repeatedly carried out this action and it was not a single or casual occurrence, it was an oft repeated, apparently strategic, action.

Attenuated tail feathers can be seen touching the water, leaving ripples. This bird touched the water multiple times; others touched only once.

Another interpretation of this action could be that the bird was using its body to shade the water and so be better able to see below the surface to the prey. On this occasion this is not likely as the sun was often obscured by cloud and, with the sun in the east and the birds facing west, into the wind, the near horizontal position of the bird while hunting would have cast as much, if not more, shadow on the water in the area of the bird’s eyes than would a near vertical position, as can be seen in the photo.

Further observation is clearly needed on this matter but for whichever reason, attempting to block the sun or luring prey, the behaviour was intentional and repeated on numerous occasions by multiple members of the flock. Again, any feedback of similar sightings would be appreciated.

All text and photos © Jenny Spry

Monday, July 1, 2013

Welcome Swallow taking larval prey from under water.

The following documents Welcome Swallow feeding behaviour I witnessed in July 2012 at the Western Treatment Plant, Werribee (WTP), some 46 km south-west of Melbourne at 38º 02’ 30” S  144º 31’ 05” E. 

Further information came from Glenn Ehmke who saw Welcome Swallows feeding in the same fashion at Fisherman’s Jetty, Anderson’s Inlet Victoria, in July 2007. Anderson’s Inlet is on the coast of Bass Strait, some 120 km south-east of Melbourne at 38º 40’ 18” S  145º 47’ 55” E. Anderson’s Inlet is approximately 130 km east of the WTP, as the raven flies.

The Welcome Swallow Hirundo neoxena is an aerial passerine found across mainland Australia, in New Zealand and on the offshore islands of both countries (Christidis & Boles 2008). On 15th July 2012 I recorded a group of 20 +/– Welcome Swallows taking larval prey from below the surface of a shallow, clear, brackish pool. None of the pictures taken at the time show any insect or larvae on the surface, or over the surface, of the water. This is believed to be the first documentation of a member of the hirundinidae family in Australia, and maybe elsewhere, capturing prey from below the surface of water.

I would be very interested to hear feedback or observations of other occurrences of sub-surface feeding behaviour by hirundinidae, from anywhere in the world.

The Welcome Swallow is predominantly an insectivorous aerial feeder that is also known, on occasion, to take prey while standing on the ground or from skimming prey from the surface of water. It is a well studied species with HANZAB Vol 7 (Higgins 2006) devoting 27 pages of text and four pages of references to the species. Despite the wealth of information within this and other literature I have been able to access, including an extensive internet search, there appears to be no previous documentation of any member of the hirundinidae family taking prey from beneath the surface of water. It is possible that swallows are already known to feed on sub-surface prey but it is not explicitly stated in readily available texts.

The one possible published exception is the report in Australian Field Ornithology by Lindsay (2012) where a Welcome Swallow was seen to fly from the direction of a eutrophic pool in a streambed while holding a small live fish in its bill, presumably taken from within the water of that pool. As the actual capture was not witnessed it is possible in this case that the fish had been at the surface of the water, or partly or wholly out of pool, when it was taken by the swallow.

It is also possible that some of the previous reports that state that hirundinidae skim prey from the surface of the water mean to include that they take prey from below the surface of the water but I cannot find a reference where this is explicitly stated.

The pool the swallows were feeding from at the WTP was ~ 10 cm to 20 cm deep and about 5 metres long by 2 metres wide. The water in the pool was clear and surrounded by low grasses and succulent herbs. The pool is ephemeral and entirely reliant on rainfall to fill it, including run-off from the nearby road.

Habitat at Western treatment Plant

The morning was partially overcast with a north-west wind blowing. The swallows were facing the wind and diving down and up over the pool, intent on their task, and presenting an opportunity to take photographs from a close range over a small area of water that restrained the very active birds within a relatively small hunting area.

Glenn says the birds at Anderson's Inlet were feeding at the Fishermans Jetty saltmarsh: “I couldn't say for sure what they were feeding on - or that they were actually capturing prey - but I suspect feeding on larvae under the surface is exactly what they were doing. Saltmarshes are renowned for being hugely productive habitats for insect larvae …”.

Habitat at Anderson's Inlet (Glenn Ehmke)

While facing into the breeze the swallows at the WTP hovered ~ 10 – 20 cm above the water and then appeared to strike headfirst at the surface. The closest description of their behaviour is in HANZAB, Vol 7 part B page 1525, where it states: “Sometimes forage by flying low into strong wind, snapping insects, then rising and turning back, then repeating process.” (Higgins 2006). Inspection of photos of the event shows that the bill, and sometimes the head as far as the eye socket, was penetrating the surface of the water and then emerging with an insect larvae. After each attack the head was shaken vigorously, presumably to remove water from the plumage and mouth, and the larvae was then swallowed. Not all attacks were successful. The whole feeding event was quite frenzied and was reminiscent of a flock of tern fishing.

Welcome Swallow with tip of bill in water

Here the head is submerged as far as the forward edge of the eye.  Western Treatment Plant

At Anderson's Inlet the head was again being submerged as far as the eye, possibly beyond (Glenn Ehmke)

In some cases it appeared that the larvae had been taken from just under the surface, 0 mm – 5 mm, because only the tip of the bill entered the water. In other cases, based on the average bill length of a Welcome Swallow being about 10.5 mm (Higgins 2006), they were catching the larvae to a depth of 20 +/- mm as the head was submerged as far as the eye.

At WTP. Here the full bill is submerged and a larvae was captured

Rising from the water the swallow shakes its head vigorously 

The larvae being caught at WTP appear to be about 10 mm long, based again on the average length of a Welcome Swallow bill. One of the more common insects at the plant is a damselfly and in the photos a “fluffy” head and multiple tail spikes can be seen on the prey item suggesting that it could be some sort of damselfly lavae. The prey being taken at Anderson’s Inlet was not seen.

Still shaking the head the prey can be seen in the beak.

Extreme crop of the head to show details of laval prey.

With insect larvae metamorphosing at a set time, it could result in Welcome Swallows gradually learning to take the prey at an ever reducing stage of metamorphose until the larvae were eventually being taken from below the water surface. Over a series of consecutive larval hatching seasons this would presumably not be a difficult learning experience when the numbers of both prey and predator are so common over a comparatively restricted area.

According to HANZAB, Welcome Swallows are migratory with Victorian birds moving north in April and May. Some Tasmanian birds also move north, leaving Tasmania in April on their way to wintering grounds in Victoria, which they then leave to return to Tasmania, beginning in September. As the feeding events reported above occurred in July in coastal Victoria the birds involved were either migrants from Tasmania or some local birds that did not migrate, or a combination of both. As I have not seen sub-surface feeding at WTP other than in July, and Glenn’s sighting was also in July, could it be that sub-surface feeding is a habit learned exclusively by Tasmanian birds and brought to their Victorian wintering grounds? Or is July the only month in which suitable larvae hatch in coastal Victoria? These are questions I cannot answer, and ones that will require more research by someone else.

It would be interested to hear if anyone has similar sightings this year, or in the past, especially from Tasmania or NSW.

Surface and aerial feeding over water, again including taking prey from the surface of water, is described in South Africa for members of the Hirundinidae, especially Grey-rumped Swallow (Psuedohirundo griseopyga), Sand Martin (Riparia riparia) and Brown-throated Martin (Riparia paludicola) (Ginn et al 1989, website 2012, Roberts 2012) but no mention is made of taking sub-surface prey.

A website article (biodiversityexplorer, 2012) states for Brown-throated Martin (Riparia paludicola) in South Africa “It forages in flocks over water bodies with other swallows and swifts, grabbing prey from the water surface.” Again no mention is made of taking of sub-surface prey. The Sibley eGuide to the Birds of North America (2012) notes for the majority of swallows in America “take prey over water”, but again does not mention the taking of sub-surface prey. Collins Bird Guide [Britain and Europe] (Mullarney et al 2001) states for Sand Martin (Riparia riparia) “Rather tied to water, often seen in numbers hunting insects in low flight over lakes and rivers”, but no mention is made of taking prey from beneath the surface.

Christidis, L. & Boles, W.E. (2008) Systematics and Taxonomy of Australian Birds. CSIRO Publishing, Melbourne.

Dolby, Tim, Johns, Penny, & Symonds, Sally (Eds) (2009) Where to See Birds in Victoria, page 109. Allen & Unwin Jacana Books, Sydney.

Gibbon, G. (2012) Roberts VII Multimedia Birds of Southern Africa. Southern Africa Birding CC, South Africa.

Ginn, P.J., McIlleron, W.G. and Milstein, P.leS. (1989) The Complete Book of South African Birds. The Struik Group (Pty) Ltd, Cape Town.

Higgins, P.J., Peter, J.M, & Cowling, S.J. (Eds) (2006) Handbook of Australian, New Zealand & Antarctic Birds, Volume 7: Boatbill to Starlings. Oxford University Press, Melbourne.

Lindsay, K.J. (2012) A possible instance of piscivory in the Welcome Swallow Hirundo neoxena. Australian Field Ornithology 29 166 – 168.

Mullarney, K., Svensson, L., Zetterstrom, D., Grant, P.J. (2001) Collins Bird Guide. Harper Collins Publishers Ltd, London.

Riparia paludicola (Brown-throated martin) sighted by JS on 22/09/12.

The Sibley eGuide to the Birds of North America version 7.1, 2012.

All images and text are © Jenny Spry and Glenn Ehmke