Friday 25 April 2014

Hybrid weavers building nests

Marwa and I caught a few Northern Masked Weavers at Bahri today and we saw a couple of Cinnamon Weavers before driving around the pools making our normal counts. We noticed a new colony of Northern Masked Weavers in the bare branches of some flooded bushes and stopped to check. One had a lot of chestnut colouring on the underparts and was very similar to the hybrid Cinnamon x Northern Masked Weaver we trapped three weeks ago, but it had no ring so was a different bird.  There were three male Northern Masked Weavers in the same bush and they all rushed to their half-built nests and started to display when a female showed up. The hybrid did the typical display, flapping its wings as it hung below the beginnings of it's nest; then it perched nearby flapping its wings, flicking its tail and bending its head forward. At least some of the time the female was inspecting the nest of one of the other birds. I will keep an eye on this nest, as it will be interesting to see if it attracts a mate and, if so, whether it produces young. We drove on a bit further and then noticed another bird that could well have been a hybrid, though it was not as clear cut as the first. Again it was in a colony with Northern Masked Weavers.

Hybrid Cinnamon x Northern Masked Weaver, Bahri Sewage Ponds 25th April 2014

Hybrid weaver at 'nest', Bahri Sewage Ponds 25th April 2014

Hybrid weaver displaying, Bahri Sewage Ponds 25th April 2014

Northern Masked Weaver from the neighbouring nest, Bahri Sewage Ponds 25th April 2014

A second possible hybrid weaver, Bahri Sewage Ponds 25th April 2014

One of the first birds we saw today was a Clamorous Reed Warbler, which flew across the path as we drove up and proceeded to sing to us from right beside the car. They are probably a resident population. The big group of wattled Starling seen two weeks ago seemed to have dissipated and we only saw one flock of about 15 birds which flew over the ringing site. the Spur-winged lapwings were as vocal as ever and we saw a couple of young birds beside one of the pools. We caught one adult in a net, giving us the chance to look at the odd-looking spur on the wing which gives the bird its name. Apparently they sometimes use these spurs to attack predators that approach their chicks.

The wing spur on a Spur-winged Lapwing, Bahri Sewage Ponds 25th April 2014 

Little Bee-eater, Bahri Sewage Ponds 25th April 2014

The number of wintering birds is falling each week and there were no ducks today, other than the resident White-faced Whistling ducks, which have paired up and are probably starting their breeding season. Most Whiskered Trens have left, but there were still lots of White-winged Terns. 

Monday 21 April 2014

Trip north to Karima

At the weekend I made my first trip up north to Karima. I went with my family and some friends and there was little opportunity for any proper birding, but I carried my equipment with me at all times and had a couple of brief trips down to the river. Overall I was a little disappointed not to see more, even though there were a few good sightings. I was particularly looking forward to the 300 Km drive across the Nubian Desert from Omdurman to where it meets the Nile again 90 Km south-west of Karima, as I was hoping I might see some bustards, sandgrouse or other good desert species. The habitat looked good, but there were very few birds, other than a couple of Brown-necked Ravens and a few doves. The final 90 Km stretch following the Nile up to Karima was a bit better, with a few good birds including a Lappet-faced Vulture and two Egyptian Vultures near an old carcass.

Lappet-faced Vulture

Egyptian Vultures

We stayed at the Nubian Rest House, which was very pleasant, though quite pricey. It lies at the foot of Jebel Barkal and I wandered over a few times to check out the birds. There were few resident birds on the rock itself, other than an active group of three Lanner Falcons (including at least one immature) and a few Striolated Buntings, but several other species were clearly using the thermals over the rock to help in migration. There were some quite big flocks circling high over the rock including hirundines, swifts (Little and Common) and lots of Eurasian Bee-eaters. Nearby at the pyramids a Western Marsh Harrier was cycling around, near an impressive flock of around 200 Yellow-billed Storks. I was a little surprised at these, as they are not supposed to be found any further north than this and I wonder where they were going. Another surprise was when I flushed a Common Snipe from very atypical habitat on the slopes of the jebel.

Lanner Falcons talon grappling

Yellow-billed Storks

I made one brief evening trip down to the river in the middle of town. One thing I was looking out for was weavers and there were lots of Village Weavers flying back and forth along the edge of the river, but none stopped in the section that I was able to access and it was not possible to locate any nests. I must have seen about 40 birds in total and several were in breeding plumage. Nikolaus gives the range of this species as south of Khartoum. I have previously seen them as far north as Sabaloka, but this is a major range expansion further north. A few years ago the first one turned up in Egypt and I would not be surprised to find populations reaching much further north up the Nile. The habitat around Karima reminded me a lot of Egypt and I wonder if they might be a future coloniser.

Karima is located at a point where the Nile has just rounded a big bend and flows towards the southwest, before bending around to the north and on into Egypt. That evening I noticed lots of birds, especially herons (about 200 Squacco Herons and about 50 each of Little Egret and Cattle Egret), heading north up the Nile (i.e. back upstream). They looked like migrants but, given the direction, I assumed they were just heading to an evening roost site. I was back again the following morning at dawn and was surprised to see more groups heading in the same direction (a similar mix as before, plus a group of about 20 Eurasian Spoonbills). This made me wonder about the use of the Nile as a migration route. These appeared to be heading 'north' up the Nile, but were presumably not going to continue following it as it bent back south again. Do these birds just follow the relevant sections then cross the desert when the Nile heads in the 'wrong' direction. I had previously assumed that they would just follow the Nile around all the bends until they reached the Mediterranean.

Eurasian Spoonbills

I was a little surpassed not to see any terns, especially given the numbers currently around Khartoum. There are no records of Whiskered Terns in Sudan north of Khartoum, which has to be an oversight given the huge numbers moving through. I had hoped to see some on this trip to fill this gap in the records, but it will have to wait for another visit.

While standing beside the Nile I saw a bird fly away from me across the river. From a rear view it reminded me a lot of a Wattled Starling, a bird I have been seeing lots of recently at Bahri. Unfortunately, I was unable to see it well enough to confirm the identification, as this would have been a significant northerly extension of the range.

Tuesday 15 April 2014

Wattled Starlings at Bahri

Since February we have regularly been seeing flocks of Wattled Starlings at Bahri Sewage Pools, but on Saturday the flock was bigger than ever with up to 200 birds present. We tried to catch some, but as with our previous attempts we had no luck. Many of the males were in full breeding plumage, and the flock included a few juveniles. Nikolaus describes the species as a non-breeder and "fairly common in the southeast, rare elsewhere". By 'the southeast' he must be referring to what is now South Sudan, so they must have been quite rare in what is now Sudan. It seems that they have either changed their status here or were previously overlooked. I have seen quite a few elsewhere, including at Soba sewage pools and several times at the KICS stables, so I find it hard to believe they were overlooked.

Male and female Wattled Starlings, Bahri Sewage Pools, 12th April 2014

We wanted to follow up on our capture last week of a Clamorous reed Warbler, so we tried playing some recordings (downloaded from Xeno Canto of birds in Egypt). We had no success, until we tried the area where we caught the bird last week. We had two birds calling back at us. One came in very close, but mostly stayed hidden from view. Hopefully we will be able to establish if there is a resident population here. Last week we also saw our first Crested Coot at Bahri and one was present again on Saturday. It is nice to confirm that they are not just at Khartoum sewage works. Interestingly, we saw none while the Eurasian Coots were here. They have now all left. 

Crested Coot, with Little Grebe, Bahri Sewage Pools, 12th April 2014

It is not often you get good views of a long-tailed Nightjar, but this one showed well after it was flushed from its day roost by a Spur-winged Lapwing. Here it can still be seen harassing the nightjar.

Long-tailed Nightjar and Spur-winged Lapwing, Bahri Sewage Pools, 12th April 2014

Last week we had a couple of Slender-billed Gulls at the site, but they had gone and were replaced by a group of 16 Black-headed Gulls.

Black-headed Gull, Bahri Sewage Pools, 12th April 2014

Wednesday 9 April 2014

Clamorous Reed Warbler netted at Bahri

In my previous post I discussed the hybrid weaver we netted last Saturday at Bahri sewage pools. However, we also saw some other good birds including a Clamorous Reed Warbler, which we netted. Nikolaus shows one record from the Nile Valley up near the Egyptian border, and shows a resident breeding population on the Red Sea coast, but nothing from anywhere near Khartoum. In this part of the world the species is non-migratory, which implies the species might have either spread down the Nile or somehow crossed from the Red Sea. I am very interested in finding out its origins, as Marwa and I are currently preparing a paper of our recent records, which discusses the potential spread of bird populations along the Nile between the Afrotropical and Palaearctic regions. This could be a good example of a species moving southward. Apparently, the Egyptian and Red Sea populations are a different subspecies, but the biometrics of this bird (see below) appear to be inconclusive.

Wing - 82 mm
Tail - 76 mm
Bill tip to skull - 25.1 mm
Bill tip to feathering - 20.7 mm
Bill depth - 5.5 mm
Bill width - 4.6 mm
Total head (bill tip to back of head) - 47 mm
Tarsus - 29.1
Weight - 29 g
Total length (hard to measure on live bird) 183 mm, then 190 mm, then 185 mm
P2 = P7
Longest primaries - 3 and 4
Emargination - 3 and 4 (with slight hint on 5th)

I hope to follow up on this bird to determine if there is a resident population at Bahri and to find out which form it is. Perhaps this can be done with tape playback.

Clamorous Reed Warbler, Bahri Sewage Ponds 4th April 2014

Wing of Clamorous Reed Warbler, Bahri Sewage Ponds 4th April 2014

There were plenty of other good birds around including lots of Sacred Ibis. There have been lots about all winter, but Nikolaus describes them as a summer visitor, so again this appears to be a recent change of status. Two Slender-billed Gulls were present, and a group of 22 African Openbill Storks was an uncommon site this far north. There were fewer migrants this week, but still plenty to look at.

Sacred Ibis, Bahri Sewage Ponds 4th April 2014

African Openbill Storks, Bahri Sewage Ponds 4th April 2014

Slender-billed Gull, Bahri Sewage Ponds 4th April 2014

Whiskered Tern, Bahri Sewage Ponds 4th April 2014

Wood Sandpiper, Bahri Sewage Ponds 4th April 2014

Friday 4 April 2014

Probable Cinnamon X Northern Masked Weaver hybrid?

I visited Bahri sewage pools again today with Marwa to ring some weavers. For the first time we noticed a small group of Cinnamon Weavers near to the Northern Masked Weaver colony we have been netting at recently. It was nice to see them, but it does mean that it will be much more difficult to know what I am catching now, as the females seem to be almost identical and one of my main aims is to find a way to separate the two. So far my concerns have been about the identification of the females and non-breeding males, but today we caught a bird that threw another spanner in the works, as it seems to be a male that is intermediate between the two species. I wonder if it might be a hybrid - a distinct possibility given the similarity of the females, the almost identical nesting behaviour, and the presence of both species breeding together at one site (I assume the Cinnamon weavers are breeding nearby, as they were in breeding plumage).

Note that the bird is moulting out of its non-breeding (basic) plumage, which is why it still has some pale brown feathers on the head and whitish feathers on the underparts. This is nothing to do with it being a probable hybrid.

Probable Cinnamon x Northern Masked Weaver hybrid, Bahri Sewage Pools 4th April 2014

Probable Cinnamon x Northern Masked Weaver hybrid, Bahri Sewage Pools 4th April 2014

Probable Cinnamon x Northern Masked Weaver hybrid, Bahri Sewage Pools 4th April 2014

Probable Cinnamon x Northern Masked Weaver hybrid, Bahri Sewage Pools 4th April 2014

I have included some photos of male Northern Masked Weavers in breeding plumage below for comparison. Although the cinnamon colouring around the head and on the breast is quite variable, I have never seen anything close to the bird caught today.

Northern Masked Weaver

Northern Masked Weaver

Northern Masked Weaver

Northern Masked Weaver

From the photos above you can see that the hybrid has a lot more chestnut on the crown and underparts than the Northern Masked Weavers. It also has a bit more black on the crown than most Northern Masked, but less than most Cinnamons (see below), though the extent of black on the head of Cinnamon Weavers varies a lot, from little more than a face patch to almost a complete hood. The photos above show that the upperparts of the hybrid are much more like Northern Masked, being bright yellow rather than golden, though it does have a couple of the golden feathers (for example on the coverts of the open wing shot) that are more typical of Cinnamon.

Cinnamon Weaver

Cinnamon Weaver

Cinnamon Weaver

Cinnamon Weaver

This hybrid individual (I will assume this is a hybrid unless good evidence arrises to prove otherwise) is very similar to photos I have seen of Yellow-backed (or Black-headed) Weaver Ploceus melanocephalus. In particular, the yellow nape and upper parts contrasting with dark head and cinnamon underparts is quite distinctive. The main difference is that this hybrid bird has a black and cinnamon head, while Yellow-backed Weavers have an all black head. This species is found in South Sudan and in Eritrea and Ethiopia up to the Sudan border. Potential hybrids will clearly have to be considered when identifying birds in any of these areas, where all three species could occur.