Ngulia Bird Ringing 2000-01

Graeme Backhurst & David Pearson

Autumn 2000

The timely arrival of the short rains brought relief at the end of the year to many drought-stricken parts of northern and eastern Kenya. In Tsavo, showers began in mid November and most nights were then misty throughout the ringing period. Two small-moon periods were covered in 26 netting days. The first, 20 November-7 December, with up to 20 people in the team was outstanding with over 23,600 migrants being ringed, including two new species for the Ngulia ringing list: a Eurasian Hobby and a Eurasian Wryneck. The Marsh Warbler total was at an all time high at 11,201 but several other species were way down in numbers. There was only one Eurasian Nightjar, only two Tree Pipits, ten Rufous Bush Chats, no Northern Wheatears (and only one Pied and one Isabelline) and just 4 Upcher's Warblers. The daily ringing total, including 417 Barn Swallows, on 28 November was an all time record 3,268.

The late December session, with a small team and no tapes played resulted in a further 1,429 migrants ringed and included a much more respectable six 'new' Upcher's Warblers plus one previously ringed at Ngulia on 14 December 1996. For comparison, on 5 December 1981 we ringed no less than 13 Upcher's.

The season's totals for the four main species were Marsh Warbler 11,942, Sprosser 6,276, Common Whitethroat 2,947 and River Warbler 850.

Use of Song Tapes

As in 1999, we played tapes of migrant songs at night in both the following years, but with growing reservations. In 2000 we played the tapes every night in the main session (20 November-7 December) but not at all in the short and less well manned second session (23-30 December). We got the impression - already formed in 1999 - that playing the tapes increased the numbers of Marsh Warblers being attracted down to the netting area. This increase in Marsh Warblers, in turn, had the effect of reducing the numbers of so-called minor species caught by the simple process of excluding them from the nets. The late December 2000 session, when we did not plat tapes at all, showed more variety.

In 2001 we continued to play the same tapes, but on alternate nights, and the results showed, quite clearly, that the species variety was greater on the nights without tapes. So should tapes have a role at all at Ngulia? We think the answer is a qualified 'Yes'.

We have established that, without tapes and without mist, hardly any birds are grounded at Ngulia. When the cloud base is but a few tens of metres above the ground, very few birds will come down to net level (2-2.5m) with lights alone. However, under these same conditions, playing tapes can bring down considerable numbers. Thus, our plan for future years is as follows: if the cloud or mist has not come down to ground level by about 0100, we will play tapes, but will stop them immediately if the mist subsequently comes down. If the mist is already down by 0100 we will not plat tapes at all. Also, if there is heavy rain and no mist we will not play tapes.

There is, we feel, justification in this flexible approach. Quite often in the past, especially in November, a week or more has gone past without any mist, and hence hardly any birds; this has been a great waste of time, energy and money and an enormous disappointment for the ringers. We hope that the strategy outlined above will mean birds every night unless it is completely clear, when we have found that tapes produce little or no effect. On misty nights, however, catches will not be influenced by tapes, and we shall therefore still be able to compare catch composition, weights and so forth with results from the past.

Autumn 2001

We again ran two sessions, the first from 10 to 29 November, the second from 7 to 17 December, a total of 29 netting days altogether. The first five nights in November were dry, but with rain on 15th, worries about the weather ended for the rest of the season. With smaller teams than in most recent years, we still managed to ring 10,252 migrants in November and a very respectable 6,773 in December with an even smaller team. Keeping rigidly to the one-night-on one-night-off tape-playing routine meant that on some non-tape nights, when the mist was not properly down, we did very poorly but we resisted the temptation of playing tapes. It was also interesting that the highest daily total (1,557 on 22 November) was achieved without tapes.

Species other than the four main ones were even more poorly represented than in 2000; 21 Eurasian Nightjars (admittedly 21 times better than the 2000 total), 2 Eurasian Rollers, 19 Rufous Bush Chats, 88 Iranias, 7 Common Rock Thrushes, 7 Upchers and 37 Barred Warblers and not a single Palearctic Wheatear. The sole unusual bird ringed was an Asian Lesser Cuckoo at night on 25 November.

The season's totals for the four main species were Marsh Warbler 7,346, Sprosser 3,696, Common Whitethroat 2,488 and River Warbler 364. The Red-backed Shrike total of 315 was remarkable, second only to the 458 in 1995; 123 of these were ringed on 18 November. Just 62 Red-tailed shrikes were ringed this season, with over a third (22) on 18 November.

Recoveries and Controls

In 1999 we had six controls of foreign-ringed birds at Ngulia so the total of three in 2000 was low; however, there was quality! A Barn Swallow ringed in Chokpak, southern Kazakhstan; a River Warbler from Slovenia-particularly amazing as the Ljubiana scheme had only ringed 171 of this species at the time; and the third control was a Marsh Warbler from Belgium.

In 2001, we had better fortune. On the first night with mist (15 November) on of the first birds extracted was a Brussels Marsh Warbler control; it had been ringed in Belgium in July. Then in the dawn round another Brussels Marsh Warbler which had been ringed in Luxembourg in early August. So we proceeded with high expectations, but we had to wait until the 19th for the next control, another Marsh Warbler, this time from the Czech Republic, ringed in early July.

Then, on 21st we caught a Norwegian-ringed Sprosser. This is the first interchange between Norway and Kenya; the bird had been ringed in SE Norway in early August. The next day we had the fifth control, another Sprosser, this time from Finland where it had been ringed in August 2000 near Helsinki. In the December session there was just one control, a Marsh Warbler that had been ringed near Graz, Austria in July. All 2001 controls other than the Finnish Sprosser had been ringed the same year.

There have so far been three recoveries from the 2000 ringing; a Sprosser to Finland (control), A Marsh Warbler to NW Saudi Arabia and a Barn Swallow to Chokpak, southern Kazakhstan (control). The 2001 ringing has so far produced a Marsh Warbler recovery in Mozambique and one controlled in NW Turkey.

Afrotropicals

A wide variety (87 species 618 individuals) of Afrotropical bird species was ringed in 2000. Most unexpected were the Wahlberg's Eagle and Narina Trogon that turned up in the bush nets. The other additions to the ringing lists were Hildebrandt's Francolin, African Palm Swift and Grey-capped Social Weaver. In 2001, we ringed 492 birds of 85 species. Interesting captures included an Adult Gambaga flycatcher on 25 November (7th example of this species) and the second ever Scaly-throated Honeyguide on 16 December but there were no additions to the ringing list.

Acknowledgements

Thanks go to the management and staff at Ngulia Lodge and to Kenya Wildlife Service for allowing us to catch and ring birds at Ngulia. For financial support we than the Wetland Trust and the Kenya Museum Society.

The above article is copyright, and reproduced by permission of, Kenya Birds magazine - a joint publication of the Department of Ornithology, National Museums of Kenya and .