Monday, April 17, 2006

Trip Report South Africa Limpopo 1-14 Mar 2006

Limpopo Raptor Ringing Expedition

March 1st to 14th 2006

Participants: Chris Sharpe, Malcolm Wilson

With the successes of the previous two trips, I imagined it would be hard to follow on with anything like those results. However it soon became apparent that the two species of Snake Eagle, Black-chested and Brown, were abundant and most certainly migrants which had followed the good rains and were in groups of upto 6 together in the thornveld areas.

In the midst of this spectacle we began to catch these and other species quite regularly, ending up ringing 45 raptors of 17 species.

Mist-netting at various camps produced 81 new birds of 41 species.

March 1

From Johannesburg, we headed north east across the highveld on the R25 counting dozens of Amur Falcon and Lesser Kestrels along the way.

Champing at the bit we resisted until we turned onto a dirt road leading in roughly the right direction.

Just before this, we came across a Black-chested and Brown Snake Eagle on a pylon. The only way I could get a trap to the birds was to walk in and so fought my way through a barbed wire fence and as I was about to put a trap down, a very large and black bull appeared out of some tall grass and began to advance, making some extremely unpleasant noises. Given my track record with large aggressive Bovids, discretion took the better part of valour and made a hasty retreat.

Not long after this frustration, we soon had our first bird, a Steppe Buzzard, which cooperated, coming to the trap immediately, unlike the hundreds of others of its species usually giving a disdainful sniff at the trap and carry on looking in the other direction.

Next bird was a Greater Kestrel, which obliged in coming down as they usually do very fast.

We passed a remote area behind the Loskop Dam Nature Reserve and to our good fortune saw a pair of Verreaux’s Eagles soaring over the bush.

March 2nd

We spent the morning mist-netting on the farm in the Olifants River valley picking up Black-collared Barbet, Black-capped Bulbul, Willow Warbler, Garden Warbler, Spotted Flycatcher, Amethyst and White-bellied Sunbirds, Blue Waxbill, Lesser-striped Swallow, Cinnamon and Golden-breasted Buntings.

March 3rd

We set off early our target was to reach a private reserve on the Limpopo river before nightfall, some 350km as the Steppe Buzzard flies. We fully intended to trap along the way and not spend too much time waiting for Steppe Buzzards to make their minds up.

An hour out of Groblersdal we came across a juvenile Lanner that had just caught its breakfast and was devouring it at great speed. This was obviously not enough, the trap and mouse had hardly hit the ground before the bird came in fast, knocking the trap for a metre before getting caught.

We caught a Rock Kestrel next, which came to the trap most unlike their cousins the Lessers, obviously taking more vertebrate prey than the insectivorous migrants.

By 0900 we had seen the occasional Black-chested Snake Eagle, which had proved too far to drop for, when, on a back road we came across a pylon perched bird a considerable but droppable distance away. It worked and after 2 minutes the classic tale-tale head bobbing started, followed by the usual squirt and launch, a steady direct drop onto the trap. Waiting the few minutes for the bird to get trapped was, as always, a very nerve wracking and adrenalin filled moment! At last the bird began to struggle and in a few seconds we had it secured.

An adult weighing 1490g with a wing of 530mm, very pleased with this, we carried on north.

Around 1300, we had dropped for a couple of uninterested Snake Eagles and had wasted an hour or so on Steppe Buzzards, when we came across a perfectly perched Brown Snake Eagle in a tree.

The bird came to the trap straight away and was caught quite soon, but as we got to the bird, it slipped a noose and was away, very frustrating, a young bird too.

At 1500 we made up with our second BCSE of the day, another adult this time weighing 1400g with a wing of 520mm.

The rains were very evident from earlier on in the day and now we had reached them. Apparently the Limpopo River was in flood and everything was green.

Looking at the map we still had a way to go so took to the main road for a while to make up some time. We had no longer started when at 1600 we saw another BCSE sheltering in a tree from the drizzle and had our 3rd BCSE of the day weighing 1300g with a wing of 533mm.

We drove in the increasing rain, wondering if we were going to make our destination, as there was a ford to cross, which was prone to flooding at times. We arrived at the Limpopo to see it in full spate, an amazing sight, considering I had been here not 3 months prior in drought conditions and not a trickle anywhere.

The ford did have water in, but if one drives fast enough these inconveniences rarely hinder the determined!

March 4th

Our camp was idyllic, and our hosts were all too keen to show us the reserve. We had put up nets around the camp, but with the rains, most birds had dispersed.

We caught Emerald Spotted Wood Dove, Meve’s Starling, Woodland Kingfisher and Kurrichane Thrush.

It was very good to catch an adult and juvenile Woodland Kingfisher, (having a more orange bill with less bright plumage) the latter only just having fledged as these migrants only arrive in southern Africa in December.

We went out into the reserve, but were restricted by the amount of standing water it was unusual to see inundated Mopane bushveld!

We saw raptors, Wahlberg’s Eagles, Bateleur, Steppe Buzzard and more remarkably a juvenile Cuckoo Hawk and an adult Bat Hawk, a first for the reserve.

In the evening we drove along the grass airstrip with lamp and landing net and dazzled a Spotted Dikkop and 3 Square-tailed Nightjars.

March 5th

Leaving at 0900hrs in ideal conditions, grey and overcast with a wind blowing, we had hardly got a km when we came across a BCSE on a pole next to the little track running along the Botswana border fence.

We dropped as near as we could and before long the bird flew to the trap, but against the wind. As the trap was up against the fence, the bird couldn’t land, bum-to-the-wind so to speak, so it did the most peculiar thing and landed the other side of the fence! It then tried to get to the mouse and trap, running up and down and getting quite confused.

Just then a chap came along on a bicycle and scared the bird off back onto its pole, the chap did not see the trap and so we waited to see if the bird tried a different approach. The bird came down again, behind the fence!

Well! we had to do something so driving slowly we pushed the bird three poles along where we could drop the trap on some grass away from the fence. This time, no problems and we had another adult weighing 1410g with a wing of 517.

We took a while and played around with some Lesser Kestrels and Amur Falcons, which were too interested in the insect life in the fields to look at our mouse and only a Red-backed Shrike came to inspect the mouse. A large flock of Black-winged Pratincoles flew across the road, some 2-300 birds heading north to their breeding grounds in the Caspian.

Following a back road through Mpangubwe National Park an hour later, we came across a juvenile African Hawk Eagle and dropped for it. It took a couple of attempts the bird got partially caught and got off twice before it was finally secured.

It was a large bird, a female, weighing 1580 with a wing of 462. Always good to ring an independent youngster which is not dependent on its parents, as there is the chance it will find a niche elsewhere giving us a clue to dispersal patterns.

An hour later we came across another Black-chested Snake Eagle, and caught the bird without hitch, another adult weighing 1320g with a wing of 533mm.

Obviously by now we were thinking as to weather these birds were on migration, had arrived or were we looking at an eruption in response to the rains?

Every year the species ventures onto the highveld, but where they come from, we don’t really know. There were too many to be a resident population, which may be supplemented by these intr-African migrants.

A few kms later on driving through a nice mix of mopane and bushveld habitat, we spotted a Wahlberg’s Eagle hiding inside a large Kirkia. A quick drop and we soon had the bird standing over the trap. As it was looking at the mice, it regurgitated a large pellet, before pouncing on the trap and getting caught.

It was a female, weighing 1350g with a wing of 460mm. We managed to find the pellet and analyse the contents. Apart from quite a bit of fur, the remains of several Armoured Ground Crickets were present, the roads alive with roaming cannibals seeking their squashed brethren.

On a roll now and another hour later we came across a Brown Snake Eagle when dropped for, came to the trap relatively soon. Caught, as many are, by just a hind toe, we processed the bird, an adult weighing 1800g with a wing length of 557mm.

In the next hour we caught another juvenile male Lanner, coming to a Zebra Finch bait, which worked very well. The bird was relatively calm for a Lanner. A farmer stopped to see what we were doing and so we gave him and his friend a demonstration and informative talk, he responded very positively.

And another Black-chested Snake Eagle, our first juvenile which weighed a scant 1090g with a longer wing of 541than the adults and a considerably longer tail which is consistent with some raptors who for some reason have longer juvenile feathers. A possibly for this is that not much energy goes into developing these first feathers but just enough to get them to grow quickly enough to enable the fledgling to leave the nest as soon as possible. Later when the young bird has been able to take care of itself it can develop the sturdier adult feathers as and when it finds sufficient food.

As usual we were taking too much time and we still had a plan to get some mist-nets up at the next camp on the Limpopo, so dashing west we only stopped for a little Shikra sitting on a telephone line. The bird came to the Zebra Finch immediately, with us about 5m from the trap!

March 6th

A relaxed morning mist-netting around the lodge produced some good birds. Situated on the edge of riparian forest and thornveld, the lodge was perfectly situated and as usual all to ourselves!

Another juvenile Woodland Kingfisher was the first here after catching several adults in early December. Also new for this site were 3 Grey-headed Kingfisher as well as a Brown-hooded.

In one 60 foot net a haul of 7 Red-billed wood-hoopoes was taken, with a Crested Barbet and a Red-backed Shrike! The former species has arguably the most disgusting pong of any bird species, most certainly of the ones I have handled! To think these birds will all pile into a tree cavity together for a night!

After lunch we took a drive upto the farm fields and played around with 50 or so Lesser Kestrels and Amur falcons. We dropped many times and got quite a few little heads bobbing, but no action. We even dropped the trap for an Osprey, which was resting on a pole! I have heard of a Fish Eagle caught with a mouse bait and bal-chatri trap.

We finally managed to catch an adult male Lesser kestrel, dropping the trap for a crowd of 4 birds on a pole.

And 90mins later we had another adult BCSE, weighing 1300g and a wing of 520mm. We dropped for another 2 birds which did not come down, and a Wahlberg’s Eagle which we thought lured from the sky. Wahlberg’s Eagles are notorious for hanging out at about 1000m up gently thermalling and keeping an eye on who’s catching what below. It is often you can catch this species by dropping under the soaring bird. This bird we dropped for and waited, till it began to drop toward the trap, but not quite, it landed 5m away onto a road kill Bronze-winged Courser and flew off with the remains! Easier to catch a dead fresh bird than live fresh mice!

30mins later we had a go for a young Little Sparrowhawk which didn’t play, but a km further on was a large Brown Snake Eagle. We dropped for the bird which took 10mins, before coming to the trap and getting caught, took the trap a good 10m before we caught up with it. It was, probably, a large female weighing 1910 with a wing of 560mm. the trap weighs 2.5kg, so quite a powerful bird to drag something heavier than itself 10m.

On the way back to camp we got a large adult Pale-chanting Goshawk weighing 985g, with a wing of 385mm. These birds usually co-operate by coming to the trap immediately and with lots of aggression, a very successful species in the dry thornscrub areas.

Late afternoon saw us back near the Limpopo River when I spotted a Martial Eagle high above us. In great haste and in one movement, screeched to a stop and got the big trap out onto the track and reversed off at top speed.

With held breaths, as this species commands, we watched the huge bird slowly turn and look as if it was going to move over the trap, but alas, it carried on and kept going back into Botswana.

I once caught a Martial in this fashion, a bird around 1500m up, slowly thermalling, which did a lovely little double take by ever so slightly hovering when it saw the mice. It came down to the trap in a great sweeping arc, almost convincing me that it was heading away, but was suddenly on the trap!

A little distance further on we got another juvenile Lanner. Whilst waiting for the bird I noticed something not quite right with the bird, its left eye was closed and couldn’t see the mouse. Moving the trap to its good side, the bird was on the trap in a second and had managed to get every noose round its feet. It was a bad eye so we cleaned it as best we could and released it. There are some people, that advocate releasing sick birds, but my reasoning is that we will never know of the survival rates if we do not ring these birds.

March 7th

Late morning again saw us leaving for another raptor run. We had had a fair mornings mist-netting with a couple of Red-backed Shrikes, 3 Ashy Flycatchers, 1 southern Grey-headed Sparrow a Paradise Flycatcher and Southern Yellow-billed Hornbill and a pair of Pearl-spotted Owlets.

Our first raptor at 1100hrs was a Brown Snake Eagle, whilst waiting for the bird to get caught we noticed the tale-tale signs that the bird was not happy with something above. Sure enough, looking up a dot maybe at 1km was a Wahlberg’s Eagle and was coming down fast.

There is nothing more exciting than to see a bird of prey, especially a hunting Eagle, dive at terminal velocity, and then accelerate! How these birds manage to stop in such a short time is marvellous.

And right next to the Brown! The two looked at each other then the Wahlberg’s began to snatch at the trap, dodging the Brown, which eventually got caught. We had to go in and get the Brown so disturbing the Wahlbeg’s, but they usually hang around and so leaving the trap where it was, backed off and processed the Brown while we waited. The Wahlberg’s came in again but landed on a fence out of sight. Once we had ringed the Brown, a juvenile weighing 1790, we released it and tried to see where the Wahlberg’s had got to, but becoming suspicious it must have cleared off. Obviously a feeding strategy of Walberg’s Eagles is opportunistic piracy! I once caught a Brown and a Wahlberg’s together on one trap!

An hour later we got our 8th BCSE, an adult weighing 1600g, probably a female at this weight and later, that afternoon, in close succession a pair of Dark-chanting Goshawks.

March 8th

During the previous evening over a G&T we heard what could possibly described as a Bullfrog on steroids. Listening I suddenly had an idea and grabbing the lamp, we went in search of the fog-horn like booming. About 30m from the camp we scanned a dead tree overlooking the dam, and there, out in the open was the massive Pel’s Fishing Owl. A real bonus as we had failed to see it at our first camp on the Limpopo, this bird is a real sought after tick for many birders. It gave us great views of it flying and calling in our spotlight.

Four White-crowned Lapwing had been pushed off the river which was still in full spate and had taken to flying over the swimming pool at dawn to land in the dam in front of our lodge. Putting a wader net up the night before, I had opened it at before dawn, disturbing a large Crocodile that had been lying under the furled net! There is nothing quite like the excitement of wading through knee deep ooze in the dark with the expectation of catching a new bird!

Sure enough, at 10mins after dawn, the four birds came swooping into the lagoon and for a second looked like all flying off again, not figuring out the net and its consequences. Two birds took off but two went for the small bit of flat mud where I had put my net across. I was at the net in seconds, unfortunately too late to get both birds, but got the one.

For such a dainty wader, the spur on its wing measured 17mm!

Whilst we were packing up, a pair of Water Thicknee came in and also got caught.

On the way to the next camp at D’Nyala nature reserve we came across a BCSE on a pylon, but right across from a farmer moving his cattle out onto the road.

We had to first explain what we were doing and that we needed him to wait a few minutes.

Fortunately the guy remembered me from a previous trip and had stopped to watch us ring a Brown Snake Eagle then and was more than happy to stop his work for us.

Once we had the bird he was very excited and got all his workers to come and see what we were doing, explaining in Sotho all the time why we were ringing the bird.

It was an adult weighing 1400g which was released to great cheers from the farm labourers!

For the rest of the day we caught only a single Shikra, a juvenile, but dropped for a number of BCSE and Browns. We also dropped for a Tawny Eagle, which came in to inspect the trap, but was too wary to follow it up.

March 9th

The following evening we went for a dazzle to try and catch some nightbirds, we missed a few opportunities, with a few Bronze-winged Coursers, Rufus-cheeked Nightjar, Double-banded Sandgrouse and a Red-crested Koraan. But the night was saved when a White-faced Scops Owl was spotted inside a big Marula tree. We dropped a trap for it and backed off waiting to see what happened. A minute went by and until I turned on the headlights to reveal a very startled little Owl on the trap! He flew off at this point, but was back on again and was caught. What a smart little Owl! It had great big orange eyes, and was visibly quite upset.

With the moon casting too much light on the track, we were finding it difficult to trap and called it a night.

Off early and our first bird was a Shikra, a rather stubborn one at that. We waited for it to come to the trap, which you rarely have to do, when I spotted a Brown Snake Eagle further down the road, which in my book took precedence! Going to pick up the trap was all the Shikra needed to make its mind up, and as I got to the trap in the vehicle, in the bird came and got caught! 2m from the bumper! We took the bird with us to process whilst we dropped another trap for the Brown.

In the time it took to process the Shikra, the Brown had hardly moved, so we carried on catching 3 Pale-chanting Goshawks and a Steppe Buzzard, the former nearly weighing a kilogram as it fattens up for its long journey north.

March 10th

We had a fairly long way to travel so we took off by 0700hrs and got our first bird by 0800hrs a Brown Snake Eagle, a large adult female weighing 2150g and possibly the one that refused to come to the trap yesterday.

An hour later after dropping for another two Browns with no success, we got a second for the morning, another adult weighing 1850g.

20mins after this and we had another on the trap, only to loose it as it slipped off a noose. At 1100hrs we made up for this one with another Brown, a juvenile weighing 1890g.

We stopped to drop for a Lanner which came in quickly, hitting the trap briefly, but getting scared off. Looking more closely at the bird I noticed it too had a bad eye, and also a ring!

Sure enough it was our bird from the 6th! It had flown, as the Lanner does, a direct distance of 60km.

So far an excellent morning and to make things better we got our 10th Black-chested Snake Eagle!!

30mins later and we had our 11th!, both adults with wings of 533mm and weighing 1330g and 1350g.

By now of course we were way behind on schedule and only stopped for another Brown which didn’t come to the trap and 2 Wahlberg’s which were more interested in a Rabbit on the roadside which was a far better option than two lab mice!

We got to our forest cabin in the Woodbush Forest and with the help of David Letsoalo, got a line of nets up for the morning.

March 11th

The morning was good with a mixed catch of birds including,

Olive Thrush, Chorester and Cape Robin-chat, Yellow-streaked Greenbul, the eastern race of Cape White-eye, Yellow-throated Woodland Warbler, Lemon Dove, Cape Batis and Bar-throated Apalis.

Raptoring was a frustration, we saw a couple of distant unapproachable Long-crested Eagles, lots of Forest Buzzards, Steppe Buzzards a European Honey Buzzard Perched next to Forest and Steppe Buzzards! We did get a Jackal Buzzard down next to the trap, but was just too wary and just stood there for 30mins. One of the reasons for our lack of success was noticed when I kept noticing a Forest Buzzard looking up into the sky, following suit, I realised it was keeping an eye on a big move of Steppe Buzzards moving over at great speed and height in a slipstream. Mere specks and only visible with binoculars, these birds were on the move in groups of 5-20.

March 12th

Heading south today, to the Oilphants River valley in Mpumalanga, and so took a circuitous route through some remote and rural homelands. On the way we dropped for 4 Black-chested Snake Eagles, to no effect. A sighting of note on the way was a flock of 1000 House Martins, never usually seen in such numbers in South Africa.

As we got further south, we noticed a significant drop in the number of Steppe Buzzards and small falcons, but managed to get another Steppe Buzzard, drop for a young Gabar Goshawk and a Lesser kestrel, which got chased off the trap by its Greater cousin!

March 13th

Not the best of dates to go raptoring on, but with a positive attitude, took a drive out into the farmland areas and soon came across a pair of Black-chested Snake Eagles a pylon length apart.

The one we almost dismissed as too far, but we found a track that seemed to head toward the distant pylon, which it did. Dropping for the bird we had to hide round the corner a short distance and wait. The bird came down to the trap 4 times, so frustrating and to make matters worse a Fork-tailed Drongo decided to fly up to the great height of the perched bird and proceed to mob it. Eventually the bird came down to the trap and was caught, al the while marvelling at our luck that nobody had come down the track and disturbed the bird which had taken 10 mins to get caught, our 12th!

We realised that the other bird was still on its perch and dropped for it in a driveway to a farm. The bird came in and was next to the trap about to get on, when a tractor cam out, disturbing the bird. This happened 3 times until the bird lost interest and flew off to a distant pole.

We had realised with shame that this entire trip we had not caught a Black-shouldered Kite! They were actually conspicuous by their absence, the mouse harvest they had responded to earlier last year had abated and they had mostly out. But we did get one, last thing on the way home.

March 14th

A quick raptor run before every one had to get on the plane in the evening took us upto Schundraai nature reserve where we got an adult male Pale-chanting Goshawk. As we were dashing to get the bird a large 4X4 pulled up who turned out to be the provincial ant-poaching unit! It was very satisfying to show him my permits and licence and proceed to give him and his mate a demonstration.

Later on we were very unlucky to have 2 Wahlberg’s Eagles on trap, but got off.

All in all a great 2 weeks of mostly raptoriing in great overcast conditions and coinciding with a great movement of Black-chested and Brown Snake Eagles. We dropped far more times than I’ve mentioned and counted some 50 BCSE and 40 BSE.