NEW TO ZAMBIA

WESTERN REEF HERON

Mid-morning on 3rd February 2006, Charles Nkhoma and I spotted an unusual egret fishing in front of Kafunta River Lodge, which lies just outside the South Luangwa National Park (Mfuwe area) in Zambia.

The bird had a piebald appearance and a rather more robust look than the egrets commonly seen in the area. It's legs were completely olive/yellow-green and it's bill was heavy and distinctly bi-colored, being mainly dark yellow/brown below and grey above. These features helped us to rule out Great White Egret Egretta alba, Yellow Billed Egret E.intermedia and Little Egret E. garzetta, but left us still unable to identify the bird.

During the next few days we saw the bird twice more but, being no closer to an answer, I sent a photograph of it to Africa Birds and Birding. Their reply made the suggestion that the bird was a Western Reef Heron E. gularis shcistacea - potentially a new species for Zambia. This was very exciting news considering the number of times that I have felt I have had an unusual sighting, only to discover that it was a fairly common bird, an experience that I share with many other amateur birdwatchers, I'm sure.

Now my photograph had to circle the globe to be scrutinized by various experts. They all immediately agreed that Western Reef Heron was the most likely candidate, but the possibility of a hybrid needed to be eliminated. The complex and close relationship between Little Egret and Western Reef Heron were discussed, as were previous instances of hybridization. However, it appeared that although such hybrids were frequent in Asia, they were very rare in Africa. Furthermore, most of the hybrids traced had a black or predominantly black bill and none show the pale bill and legs of this individual. The piebald plumage turned out to be not unusual for an immature Western Reef Heron and so it was confirmed as that species. It was also pointed out that an immature bird was more likely to wander further afield, but few would have predicted one arriving in the Luangwa Valley.

Sorting out these egrets and herons is made more difficult because not all agree on how they should be treated. In Africa there are four forms involved:
1. Typical Little Egrets (garzetta); wide spread in Africa and Eurasia
2. West African Western Reef Herons (gularis gularis); West Africa
3. East African Western Reef Heron (gularis schistacea); East Africa, Middle East, India
4. Dimorphic Egrets (dimorpha); Madagascar and East Africa

Some authorities treat all these forms as one polytypic species (1 and 2=3=4) and many now split them into three (1 and 2=3 and 4). It is interesting to note that in East Africa, shcistacea is reported inland more often than dimorpha, which would also accord with this record.

One final species that deserves a mention in the mix is the Little Blue Heron E. caerulea of the Americas. Although highly unlikely, this species has been recorded in South Africa and at a certain age it also shows a variegated white and grey plumage. However, the distal half of it's bill is always black and it's neck and head are proportionally shorter than birds in the Little Egret complex. Many thanks to all those who helped getting this bird identified and accepted as a new record for Zambia.

Greg Poole

Kafunta Safaris
Kafunta@luangwa.com
Phone 00260 6 246046
After hours 0026 6 246132
www.luangwa.com