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This appeared in the latest online edition of Veterinary Science Tomorrow. It may be a little off topic for the Kruger Forum but it might be interesting to note possible “defence meganisms" that birds might have against their predators.

24 May 2005
How birds keep secrets in color

Songbirds are able to communicate with potential mates using plumage colours while remaining inconspicuous to avian predators, Swedish researchers suggest in PNAS this week. They do so by using colors that the larger birds are less able to discriminate from the background. Ultraviolet plumage coloration, which reflects light in the range of 355-380 nanometers, has long been known to serve as a secret communication channel in songbirds, exploiting a shortfall in the mammalian visual system. But it has not been clear how avian predators, which can see ultraviolet, are excluded. Ornithologists Olle Hastad, Jonas Victorsson, and Anders Adeen, all based at Uppsala University, present evidence that small passerines such as the robin Erithacus rubecula, brambling Fringilla montifringilla, and golden oriole Oriolus oriolus exploit differences in the maximum sensitivities of their own visual systems and those of their potential bird predators.

Using retinal models for the songbird and predator visual systems, the researchers compared the reflectance of the head and chest plumage of 18 species of songbirds to that of their typical Swedish forest habitat. Against the appropriate background, the plumage was significantly more visible to the songbirds than predator birds, they report. "I'm really pleased to see this work published, because I always thought that the notion of UV signals being a private channel [of communication] never squared with the fact that avian predators of birds can see UV," Innes Cuthill, professor of behavioral ecology at the University of Bristol, UK, told The Scientist. "This paper shows that, yes, there is potential mileage in the argument, because raptors aren't as good at discriminating colors in the UV waveband as passerines," he explained.

Evolutionary biologist David Harper, based at the University of Sussex, UK, agreed that the study "introduces an interesting idea that songbirds can communicate with each other without being conspicuous." However, he also expressed concern over some aspects of the paper, particularly the lack of detail regarding the methodology and some of its assumptions. "This is one of those cases where we have to curse word limits," he said. "Hopefully, future papers in less prestigious journals will be more enlightening." Peter McGregor, a behavioral ecologist at Cornwall College Newquay, whose own research has centered on animal signalling, noted the "striking comparison with bioacoustics," in particular the private "seeet call" (reference 1) of some bird species. But he also echoed Harper's concerns. While studying sound is relatively straightforward, he told The Scientist, understanding color and the visual sense is much more challenging. For example, plumage signals are "omnidirectional and always on", in addition to being subject to large variations in light regime throughout the course of the day, season, or year.

McGregor pointed to the study's reliance on retinal models of both songbird and predator visual systems. Just looking at retinal pigments isn't enough. "Retinas are hooked up to brains, and brains can do all sorts of flashy processing," he said. In addition, there is a crucial distinction to make between what is signal and what is information; only the former is the result of selection. "Hastad et al. have found a correlation, not direct evidence of a private communication channel." Adeen admitted this is only the start, but emphasizes the nature of the differences between songbird and raptor/corvid visual systems. "We are looking at the tuning of maximum sensitivities. Raptors are sensitive some way into the UV [range], but their maximum sensitivity lies elsewhere," he told The Scientist. "As the title of the paper suggests, songbirds are less conspicuous, not inconspicuous."

Reference 1

E-mail address:The Scientist Daily (support@the-scientist.com)

Original web page at The Scientist
{Edit by DQ: The names are probably wrong, as they showed as Håstad and Ödeen atfer the servercrash}

I recently overheard friends discussing that they had ticked the African Finfoot, which was one of the Big 5 Birds. Does anybody know what the 5 birds are?

It's actually the Big 6; For Kruger it's Lappet faced Vulture, Martial Eagle; Saddle billed Stork, Kori Bustard, Ground Hornbill and Pel’s Fishing Owl.

Have a read here.

I post this on behalf of Mike Lodge

THE PELICAN CHALLENGE ON THE WEST COAST
by Mike Lodge

The near-threatened Great White Pelican (Pelecanus onocrotalus) is arguably the largest fish-eating seabird endemic to the South African West Coast. It can be recognised in flight by its huge wingspan, S-shaped neck, long beak, its penchant for soaring in thermals and for flying in formation. Some call it the Jumbo Jet of the birds.


Photo courtesy of UCT's Avian Demography Unit, taken by René Navarro

A number of years ago, a pig farm near Cape Town started feeding their pigs chicken carcasses. These were gutted before feeding and the offal was thrown into a hole in a remote corner of the farm. Before long, various scavenging birds, amongst them the Great White Pelican, started eating this regularly supplied and nutritious food. Unfortunately, as we all know, most chickens battery-reared today are fed growth hormones, and it is suspected that this has had an effect on these pelicans.

It is postulated that this plentiful supply of hormone-enriched feed caused the pelicans to breed better than is usual, and their offspring went to eat where their parents took them –to the pig farm. Furthermore, it was believed that they never learned that their waterproof feathers, long beak and gular pouch were so ideally suited to bulk fishing in the sea, for here were easy pickings on land. Today, a whole generation of pelicans has grown up with no knowledge of fishing techniques, or even what a fish is, or looks like.

When the authorities finally realised what was happening on the pig farm, they intervened and closed up the offal hole, effectively cutting off this bountiful food supply. After some initial confusion during which some of these birds died from starvation, the remaining pelicans started looking for alternative food sources, by seeking in an ever-widening search pattern. After some time, they found that some unpopulated, predator free islands in the mouth of the Langebaan lagoon just outside Saldanha Bay had thousands of defenseless gannet, cormorant, penguin, oystercatcher and gull nests, ripe for easy pickings. These hungry pelicans waddled through the breeding colonies, scared the resident parent birds away with their daunting size, and swallowed every egg and chick they could find, in many cases, decimating local populations of our endemic sea birds. The Jumbo Jet of the birds had become the Jumbo Vacuum Cleaner. The 2006/7 breeding season yielded a virtually zero production of hatchlings to complement the West Coast seabird population.


Painting by Mrs. Binks MacKenzie

These pelicans cannot be shot as the species is listed as “near-threatened” in the Red Data Book, and besides, there is no way one can identify an ex-pig farm bird from a normal one at a distance. They cannot be poisoned without serious risk to other life forms. In the meantime, these birds are breeding, and passing on their bad feeding habits in turn to their fledglings, thereby exacerbating the problem.

As the islands are part of the proclaimed West Coast National Park, the SANParks Honorary Rangers (HRs) have teamed up with Park permanent staff under the watchful eye of avian scientists at the University of Cape Town. The idea was to create a rotating presence on these exposed and wind-swept islands during this year’s seabird breeding season (October to January), in order to scare off pelicans whenever they land. This is a lonely, risky and labour-intensive operation entailing much scrambling over rocks and climbing to high ground to watch, and down again to chase, followed by more climbing. The teams operate in 5-day shifts on the two bigger islands, Jutten and Malgas. Their day starts at first light (05h00) when the pelicans arrive and ends at sunset (20h30) when they leave to roost on the mainland.

The idea is that each island is divided in two, with one half being left to the pelicans to carry on with their bad habits, while the other half is considered as a “pelican-free” zone and the birds are actively chased from these parts of the islands. This effectively provides comparative zones on each island, where one is a control zone showing what happens if we do nothing, while the other indicates the results of the chasing operation. A weekly, and in some cases, daily breeding success count is maintained by the HRs on the islands, as well as other possible sources of predation such as Cape (Kelp) Gulls and Cape Fur Seals, so that the bird scientists can assess the impact that chasing has had on the pelican predation and then use this data to make a decision on the way forward for next year’s breeding season.

Once again, man’s thoughtless actions have initiated a complex web of change that is not easily unraveled. We already know that an unthinking motorist throwing an apple to a baboon at a lay-by to impress his child is signing the death warrant of that animal, for the day will most certainly come when that animal will be shot by other folk who are sick and tired of the marauding baboons who have become used to free food as supplied by other thoughtless humans. A life lesson for the reader is not to ever feed a wild animal, no matter how “sorry” we feel for it or how cute it is. We don’t realise the longer-term implications of such acts, and in many cases, what starts out as an innocent attempt to supply a perceived shortage of food, results in an unforeseen catastrophe later.

So what is the long-term answer? Everyone is feverishly working on a solution, and the island teams are chasing pelicans from the pelican-free zones and gathering important field data during their shifts on the islands, but in the meantime, our coastal bird populations are under serious threat. Bird scientists are hoping that the pelicans will get the message to stay off the islands, and scientists are happy to report that some pelicans chased from the islands have been spotted catching fish in the sea. However, it remains to be seen if they can all switch to this sole method of sustenance and desist from pillaging the seabird populations on the islands into the future.

Mike Lodge
Honorary Ranger
West Coast National Park

The following came through on SABirdNet and I thought it made real interesting reading

______________
Seabird born in Summer of Love still breeding in Wales By Michael McCarthy, Environment Editor Thursday, 10 July 2008

Alamy

Razorbills typically live for 28 years. A seabird that hatched in the Summer of Love – 1967 – is still breeding on the Welsh cliff where it was born, 41 years later. Hippies were wearing flowers in their hair and the Beatles were singing "All You Need Is Love" when the bird, a razorbill, emerged from its egg on the island of Bardsey off the Lleyn Peninsula in North Wales.

But four decades on, with hippies and their creed virtually forgotten, and the Beatles now part of musical history, the same bird is still going strong on its cliff, having outlived its species' typical lifespan of 13 years by more than 200 per cent.

It is the longest-lived razorbill known, and its longevity is proved by the fact that it was ringed as a chick, and when examined on Bardsey this summer, was found to be still carrying the leg ring with its unique number.

The razorbill is one of 12 record-breaking long-lived birds reported yesterday by the British Trust for Ornithology (BTO) in the journal Ringing and Migration, with the age of all of them established by ringing. They include a 31-year-old curlew, a 20-year-old turnstone and a 13-year-old barn owl, as well as a black-headed gull which has been flying for 27 years around the parks of central London – it was ringed in Hyde Park in 1981 and its ring number was re-read in St James's Park this year.

Although the oldest of its kind, the 41-year-old razorbill is not the oldest-known bird in the world. That distinction belongs to another seabird, a Manx shearwater, which is also an inhabitant of Bardsey.

When it was recaptured and its ring number read on the island this summer it was proved to be 54 or possibly 55 years old. It was first ringed in 1957, and as it was ringed as an adult, and Manx shearwaters do not return to their native island to breed until they are at least three years old, its age must be 51 plus at least three years.

In winter, Manx shearwaters migrate to waters off Argentina and Uruguay, a round trip of about 9,000 miles, and with long foraging trips in the summer breeding season, the trust estimates a bird may fly at least 32,000 miles in a year. It also estimates that the 54 to 55-year- old bird on Bardsey may have flown 1.8 million miles – almost equivalent to four round trips to the moon and back. "There's not an awful lot of predation pressure on seabirds, which is why some of them can live so long," said the trust's Mark Grantham.

"If you can survive the period of being a chick, and figure out where to get your food in the first winter, and then survive fishermen's nets and oil spills, you've got a reasonable chance of living a hell of a long time."

The older birds were recorded on Bardsey because the island has had a bird observatory with continuous ringing for more than half a century. The island's Manx
shearwater was the oldest known bird in the world, Mr Grantham said, but the performance of the razorbill in living to 41 was "absolutely phenomenal". "We might even see it hit 50," he said. "I'd be surprised – but then I'm surprised that it's passed 40."

Beats the American birds!

Just for interest sake.

New article on the Veterinary Science Tomorrow website

Super-fast vocal muscles control song production in songbirds

Songbirds use complex song to communicate with one another. Many species are able to modulate sound faster than ordinary vertebrate muscles are able to contract.

Reporting in the July 9 issue of the online, open-access journal PLoS ONE, Coen Elemans and colleagues at the University of Utah found that the European starling (found throughout Eurasia and North-America) and the zebrafinch (found in Australia and Indonesia) control their songs with the fastest contracting muscle type yet described, the so-called superfast muscles that can produce work at frequencies over 100 Hz.

The vocal muscles of songbirds can produce work up to frequencies of 250 Hz and can contract and relax in 3-4 ms, which is a 100 times faster than it takes to blink an eye.

Superfast muscles were previously known only from the sound producing organs of rattlesnakes, several fish and the ringdove. Elemans and colleagues now show that songbirds have also evolved this extreme performance muscle type, suggesting that these muscles, once thought extraordinary, are more common than previously expected.

The researchers also show that superfast muscles provide more precise and faster control of song modulations in birds than previously thought physically possible.

Did not find a topic about brood parasites so posting this as its own topic

How birds spot the cuckoo in the nest
From Veterinary Science Tomorrow

It's not always easy spotting the cuckoo in the nest. But if you don't, you pay a high price raising someone else's chick. How hosts distinguish impostor eggs from their own has long puzzled scientists. The problem remained largely unsolved while looking at it through our own eyes. It was only when people started thinking from the birds' perspective that they began to understand how hosts recognise a cuckoo egg in the nest. Knowing that many bird eggs reflect UV wavelengths, Honza wondered whether altering the reflected UV spectrum of an egg would affect a bird's ability to recognise it as foreign and reject it. Would a blackcap recognise and evict an impostor egg if the reflected UV spectrum were different from the wavelengths reflected by the bird's own clutch? Teaming up with Lenka Pola iková, Honza headed into a near-by forest to test blackcap responses to impostor eggs.

But instead of testing the birds' reactions to real cuckoo eggs, the team found abandoned blackcap eggs, introducing them as impostors to successful blackcap clutches. Having identified nests with well-established clutches, the team coated some impostor eggs in UV blocker, to alter their UV appearance, and others in Vaseline, which didn't alter the egg's UV reflectivity, before planting the impostors in their new nest. Then the team kept their fingers crossed, hoping that the nests weren't washed out by a heavy downpour or raided by a hungry predator, as they waited 5 days to see if the parents rejected the interlopers. Of the 16 eggs coated in Vaseline, 11 of the impostors were accepted by the nesting parents, while five were rejected; most of the interloper blackcap eggs were visually indistinguishable from the nesting parents' own eggs and were accepted as belonging to the brood. However, it was a different matter for the birds sitting on UV-block-coated impostors. Seventeen brooding parents evicted the strange looking egg, pecking at the shell until they had made a large enough hole to stick their beak in and carry it away. Only 11 blackcaps accepted the interloper with its altered appearance. The UV appearance of the eggs was very important in enabling the blackcaps to recognise the new eggs as impostors. Having found that an interloper's UV appearance is key to its acceptance in a clutch, Honza is keen to see whether cuckoos try to outsmart their victims by choosing clutches that closely match their own eggs' UV reflectivity.

Science Daily
August 5, 2008
Original web page at Science Daily


The full text of a related article titled: "Experimental reduction of ultraviolet wavelengths reflected from parasitic eggs affects rejection behaviour in the blackcap Sylvia atricapilla" can be found here. I have not read it though.

From the 30 September issue of Veterinary Science Tomorrow. Just for interest sake.

Crows seem to be able to use causal reasoning

Crows seem to be able to use causal reasoning to solve a problem, a feat previously undocumented in any other non-human animal, including chimps. Alex Taylor at the University of Auckland, New Zealand, and his team presented six New Caledonian crows with a series of "trap-tube" tests. A choice morsel of food was placed in a horizontal Perspex tube, which also featured two round holes in the underside, with Perspex traps below. For most of the tests, one of the holes was sealed, so the food could be dragged across it with a stick and out of the tube to be eaten. The other hole was left open, trapping the food if the crows moved it the wrong way. Three of the crows solved the task consistently, even after the team modified the appearance of the equipment. This suggested that these crows weren't using arbitrary features – such as the colour of the rim of a hole – to guide their behaviour. Instead they seemed to understand that if they dragged food across a hole, they would lose it.

To investigate further, the team presented the crows with a wooden table, divided into two compartments. A treat was at the end of each compartment, but in one, it was positioned behind a rectangular trap hole. To get the snack, the crow had to consistently choose to retrieve food from the compartment without the hole. A recent study of great apes found they could not transfer success at the trap-tube to success at the trap-table. The three crows could, however. "They seem to have some kind of concept of a hole that isn't tied to purely visual features, and they can use this concept to figure out the novel problem," Taylor says. "This is the most conclusive evidence to date for causal reasoning in an animal." Three of the crows did fail at both tasks, however. The team plans further work to investigate why.

New Scientist
September 30, 2008

Very interesting Francois!

This alss explains why there are always 6 crows in my area, three clever ones to help the three not so clever ones

Wow...interesting.

My Dad used to tell a story about a crow. When we used to have milk delivery at our home, in glass bottles, this crow would peel out the stopper and sip the milk. That would make the level in the bottle drop.
So....he would go & get a stone, and another stone, and another stone, dropping them into the milk until the level was up to where he could sip it again. Smart, eh?

Very Clever CC.

If you did not watch out you could get "stoned" on milk

I have been getting some really great photos of insect eating birds through our bedroom window in Marloth. There is a tree that is often visited by these types of birds. I do however not sit next to the window the whole day, waiting for a bird to visit the tree…I have learned a trick. I have started to notice how different types of insect eating birds will travel together in a “flock’ …going from one tree to another.,…when they are in the area around the house I know they will visit this specific tree and then I race to get to the window. The tree will then be full of different kinds of insect eaters. The birds I have noticed normally travelling together like this are: Chinspot Batis, White-backed Puffback, Yellow-breasted Apalis and Long-billed Crombec. Sometimes these birds are also accompanied by: Scimitarbills, Orange-breasted Bush-Shrikes and the Grey Tit-flycatcher.
Have to say, if we visit the park now and spot one of these birds, I will spend some time there because you will probably then also get sightings of other insect eaters in the same area.
Anybody else noticed this type of thing?

Yup, it's called a 'bird party' and is quite common throughout different habitats, your feathered gang in Marloth being a typical bushveld party. It's obviously a bring-and-braai type of thing since everybody in the party has to provide their own food.