Simon Thomsett

Category: Falcons, Tsavo National Park | Date: Dec 22 2008 | By: simonthomsett

Laila wrote in one of her recent entries that we witnessed the rare Ovampo Sparrowhawk make a “food pass” in mid air. Food passes are essential when it comes to one mate giving food to another or to one of its young. But within a pair they serve a purpose in themselves. For example: When a pair need to maintain their bond at the onset of the breeding season, the male will dash off and get food, prepare it, and race back to present it to the female. In some species food is presented by either sex to the other throughout the year in an amicable way. Large eagles like Crowned Eagles stay together all year round and share their meals. We witnessed a male Pygmy Falcon in Tsavo West make a fast slanting dash from his dead tree across the road and smack into a grass tussock. He emerged quickly with something quite big in his talons and took off at top speed to a group of trees a few hundred meters away. We followed and sure enough we saw him present it to his mate and shortly afterward they mated. Off he went to go and see if he could find more! The presentation between Pygmy Falcons is usually bill to bill, accompanied by a lot of appeasement calls to reassure each party that nothing violent was about to happen. It is fairly obviously a demonstration to the female that the male is a grand food provider and will look after her and their young.

Aerial air-to-air passes of food often take place among those species of raptors that are heftily armed and killers of avian prey. So it occurs more often within large falcons and accipiters (Sparrowhawks and Goshawks). It is as though they do not want to make any contact. The female can be twice the male’s weight and in the confusion of being handed food she might cause harm. Indeed the act of mating in these species is a well orchestrated business with every sign being made before-hand to calm what could be a dangerous mission. The Ovampo Sparrowhawk food pass was just missed being captured on the camera although Laila got both the adult female and male neatly posed in a dead tree and in mid air. The female had sat on the nest all morning and had flown off her nest when the male came in calling gently. She flew to a dead tree first. We had half an hour previously seen the male zip over our heads after a small bird. The bird put into cover high in the tree canopy and the male poked about until out it flew to be chased out of sight. The male seemed committed and we both felt a bit sorry for the small bird, who may well have been the plucked and headless morsel presented to the female. In short he flew in, flipped over and threw out the food, which was snatched, dropped and caught. The food pass was so dramatic that I doodled a pen and ink drawing so as to capture the moment.

Drawing of food pass

I was in Hell’s Gate National Park this morning. Oddly for this time of year I saw a lot of pre-nesting behaviour. The Verreaux’s Eagle pair were nest building, when I would have expected them to have a large chick. I saw Rüppell’s Griffon Vultures on large chicks however, a little more developed than at other colonies. The Augur Buzzards had had a few chicks on the wing but it looked like a few pairs had smaller young. On my way out I saw a pair of Lanner Falcons. The male was dashing about at high speed and the female kept flying underneath him and presenting her feet, as did he. I assumed he was passing food, but looking at the photographs I saw he had nothing. Yet this dry run was repeated time after time.

Picture of Lanners “mock” food passing

Clearly the behaviour alone, not the food itself was important to them. It was a game. They went through the same routine in “mock” practice. That was an interesting insight as I had not appreciated it before nor would have learned about it had it not been for the high speed shutter of the camera.

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Tags: buzzards, food pass, mating, ovampo sparrowhawk, pygmy falcon, vultures

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Category: Falcons, Raptor Expedition | Date: Dec 15 2008 | By: simonthomsett

The falcon stooped and fell across the sky to rebound among a small flock of birds. She mounted high again, turned and powered herself down for another onslaught. They flew out of sight and the result was unknown.

Since the dawn of man few things in nature have been so exciting to watch. This same scene may well have been witnessed while the pyramids were being built, or by some ancient hominids trudging their way across ankle-deep volcanic dust in northern Tanzania. All would surely have raised an eyebrow and dropped their jaw in awe.

The “stoop” is a weapon used by falcons and some other raptors such as large eagles. It is a trick, a sleight of hand they have up their sleeve to propel themselves faster than any known creature on earth. We all have some inherent primitive wish to see an object arc across the sky to its destination, be it a rock, an arrow or a ball. The trajectory has aim and purpose. A falcon’s stoop looks so set in its path that nothing could alter its headlong rush. Its mastery overshadows the violence.

I have seen the word “stoop” weakened by it meaning to bend over, or to describe a certain part of a front veranda. It is not a very inspiring word when used alone, but when used in Shakespearean prose, such as “She stoops to conquer” the word sends a cold chill down my spine. I will never tire to witness stoops done in play, vengeance and in deadly pursuit.

I was in thick traffic at the time entering a particularly unpleasant area of Nairobi and brooding on bad thoughts. The sky suddenly opened before me and down she came, her wings clipping sharply to her sides. She folded, and shot in a downward slope, then she started flicking her wings again. I knew this to be a “feint,” a false move, meant to confuse, so I looked down and ahead. Streaking along the traffic over the transmission wires and untidy security barbed walls of go-downs, was a flock of mixed birds. They swerved the moment she fell, then carried on as fast as they could. She feinted again and the birds changed direction, but with a few less who took a course over flatter ground. Then she banked over and upside down to get as much leverage from the wind beneath her wings to drop down on her back.

The speed is indescribable for, in a less than a second, she had covered hundreds of meters in a flat unchangeable trajectory and was a blur. Her first stoop was not intended to kill, I am sure, but to separate the flock still more. She curved out in a long spiral into the sky and smoothly turned over inverted again for a second stoop.

She was a haggard Peregrine, and she was perfection. I had taken Tim (the Lanner) out flying the other evening. He has still to take permanent leave and reappears every few days. I asked Jonathan to swing the lure and I gave the camera a go. I am nowhere near as good as Laila but I was impressed by a picture of Tim upside-down, turning and preparing to stoop down and towards the camera.

You can see a few of the top (upperwing coverts) feathers, which are very stiff, bending out from the top of the wing camber. They are obviously in very low pressure, near vacuum, turbulent air. The underside must be in very high pressure air.

There is some aerodynamic reason why falcons like to turn over in a dramatic roll, look over their back, and then use all that latent energy piled up under the wing to surge downwards. It makes sense to use the lifting wing, the wrong way up to hurtle the falcon down. Often at the apex of the inverted roll they row their wings, to fly down. This initial energy throws the falcon down into its dive.

In movies one often sees an airplane that is flying slightly low and parallel, lift up, bank and pull away showing its belly. It is the “must do” flying shot in all films. It is unnatural and from personal experience a bit unnerving. A falcon or pilot can go down simply by putting the nose down, but they would loose that advantage which is the lifting power of the wing to give it that first few seconds of downward force. Down and into that wonder of nature called the “stoop.”

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Tags: Falcons, raptor behavior, stoop

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Category: Raptors, verreaux's eagle | Date: Dec 10 2008 | By: simonthomsett

When I first started working in raptor conservation for the Peregrine Fund in early 1990s, my then boss Dr. Rick Watson and I discussed the various merits of raptors. How would we best promote them? They are persecuted widely in Kenya and are not viewed as beneficial. There is very little in the way of appreciation of raptors that actually helps their protection in rural Kenya despite their images being displayed on the back of passenger minibuses (Matatus), on banks, or in the media. There is some to be sure, but I have a feeling that there is less than there was. What raptors there are in human habitats are there mostly because they have evaded persecution. Some have prospered in these altered landscapes, but most have declined or become locally extinct.

Raptors do play a role in curbing plagues of rodents, small seed eating birds, hyrax, monkeys, pigeons and such like. By explaining to an audience the amount eaten (possibly amounting to thousands of tons per year in farming lands of Kenya) it is easy to show a beneficial aspect. Take the raptors away and these prey species will continue to live, multiply and consume more human food. There is the famous example from some unclear study area in South Africa, where the sheep farmers shot out the Verreaux’s Eagle, who undoubtedly took a few live lambs. Within a few years the hyrax swarmed off the Kopjes and out into the sheep pastures, and despite the heavy gun fire wrought by the sheep farmers, they accepted that they lost much of the total sheep productivity than when they had the eagles. Tolerant farmers had eagles, a few wary hyrax, and lots of sheep.

I never really understood that. Predators have been proved in many studies to have minimal effect on the numerical density of their prey species. Disease and starvation are the leading causes of mortality in all species. A few predators thrown into the mix makes not one whit of deference to healthy populations. There is no way a swarming mass of millions of Red Billed Quelea, or a heaving mountainside of plague rodents in the highlands of Ethiopia are going to be affected in the least by birds of prey. Not if you count the amounts eaten per individual raptor and total it up. Impressive as it may be, raptors do not exert that sort of pressure. This argument has been used against those wishing to persecute raptors on Game Bird shooting areas. Grouse are killed by Peregrines, Harriers and Golden Eagles. It is their natural prey. Some game keepers still persist in persecuting raptors so as to increase the amount of grouse. In reality there is no difference between those areas with hawks and those without. The main issue for grouse numbers is food and shelter.

One thing I noticed when on a wheat farm was that a single roving falcon or harrier sets up huge spirals of panicked birds ahead of it. As the hawk moved around conserving energy and looking for easy pickings, the prey burned up so much energy and were highly stressed.

Drawing of Harrier scaring doves on farmland

The hawk was a “scare crow,” and it kept the birds from eating. Ultimately must mean less small birds. I should imagine the fat and unfearing hyraxes of South African sheep farms waddling kilometers from cover were sent into a panic when they finally did spot a Verreaux’s Eagle. One Verreaux’s Eagle would not eat that many hyrax, but it sure as heck would change their habits.

In a landscape without raptors prey species may not fear stepping out unprotected into the open. It is this fear, more than the actual mortality of prey that I am sure plays and enormous evolutionary role. It is an understudied aspect of predation.

Tags: beneficial raptors, effects on prey, golden eagles, harriers, verreaux's eagles

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Category: Eagle, Falcons, Migratory raptors, Raptor Expedition, Raptors, Tsavo National Park | Date: Dec 09 2008 | By: Laila Bahaa-el-din

Despite having got a few photographs of raptors in Tsavo West over the first three days we were there, it was rather disappointing. We saw very little in the way of vultures or any other raptor for that matter. We didn’t even see any of the lions or elephants that Tsavo is famous for. The only thing that did not disappoint was our place of stay with friends at Finch Hatton’s which is as beautiful and friendly as ever. In the wood by Finch Hatton is where we saw four species of hawk and heard a fifth.

We left Tsavo feeling a little glum and spent three days at the coast on a Southern Banded Snake Eagle mission. We saw two fleeting glimpses of the bird as it disappeared into thick forest so perhaps we will need to return next year for photos.

We drove back through Tsavo East National Park and were amazed at the contrast between what we got in three days before going to the coast and what we got in three hours in Tsavo East. Before sunset on that first day back, we saw three Wahlberg’s Eagle nests, a Martial Eagle nest, Fish Eagles, African Hawk Eagles displaying and lots of Bateleur Eagles. The red elephants of Tsavo also made several appearances.

Young Wahlberg’s Eagle on nest

African Hawk Eagle

We spent one night in Tsavo East before moving back to Tsavo West where we hoped to finally get the migrants we had been waiting for. Back in Tsavo West, we had a completely different experience from the previous time. We went briefly to Ngulia Lodge to talk to Colin Jackson, Graeme Backhurst and David Pearson, who were mist-netting thousands of migrants. It was certainly the premier destination for migrants and their human followers.

We also saw many more raptors and mammals this time around. It rained for our whole second night and continued to do so as we set off in the morning. Not too far down the road, we saw a couple of cars stopped and all the passengers standing on the road. We slowed down and asked if everything was alright and they responded that they were just looking at a Sooty Falcon. We jumped to attention - the Sooty Falcon is one of our much needed species to photograph. The observers of the falcon were none other than migrant-seeking birders Fleur Ngweno, Brian Finch, Gordon Boy and others! The rain had brought in the migrants and the premier birders.

We exchanged phone numbers with the birders and promised to be in touch if we saw anything exciting. We didn’t drive too long before we saw another falcon, accompanied by seven others: Amur Falcons! We watched as they sped through the air with full crops, catching termites in the rain. It was good to see but frustratingly rainy and dark so photographing them was tough. A little further on, we saw a few more and stopped. We watched as a swarm of over 200 Amur Falcons flew over us. We let the birders know what was going on and they turned up and were excited to see so many migratory falcons in one go.

Female Amur Falcon

We camped near Finch Hatton’s that night and on our way to our campsite, we found a vulture roost. Simon had been worried that a large roost he used to know from a different location might have been wiped out by poisoning but we counted over 80 individuals at this new site so concluded that the roost must have moved.

We went back to the forest by Finch Hatton’s first thing in the morning. We saw rare Ovampo Sparrowhawks swapping food in the air, Cuckoo hawks building a nest, an African Goshawk, a Fish Eagle and a Harrier Hawk and heard the Little Sparrow-Hawk calling, all in a little patch of Yellow Fever forest by the lodge. It was a great photo opportunity.

Ovampo Sparrowhawk with prey

Cuckoo Hawk

This first 11-day trip ended up being immensely successful, but it also highlighted some of the difficulties we will have throughout this expedition. If we had made conclusions after we spent our first three days there, we might have said that raptors in Tsavo are not doing very well. But spending those extra four days there on return from the coast proved otherwise. It is going to take a lot of time, patience and collaboration with other people to get an idea of what is happening over the whole of Africa.

Tags: Eagle, Falcon, Hawk, Tsavo, Vulture

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