The area and duration of the current Brown-veined White Belenois aurota movement in Tanzania and Kenya would seem to be quite extraordinary.
Brown-veined White in Arusha 14 February, 2007 (Anabel Harries)I first became aware of this Brown-veined White (et al.) migration on Tuesday afternoon February 6 as we drove south on the main highway toward Dar with Jack & Kathy Wigan heading towards Chalinze from the Saadani NP junction.
Returning from Dar to Arusha the next day (7/2/07) these butterfies were an almost constant feature as they crossed the main road more or less southwards during almost the entire journey.
Vast numbers were also present on the Angyata Osugat on February 13 nectaring on the flowering Acacia mellifera.
Huge numbers, frequently reminding me of snow storms in the highlands of Scotland in the middle of May, have been passing through Kwaiidi in western Arusha and elsewhere in the district and also southwards at Maweni farm at 1300m; thus they are easily crossing the West Usambara barrier and have been doing so all this week, especially on Wednesday 14 and continuing through Thursday 15 and Friday 16 in Arusha.
My lepidopterist hero Torben Larsen says:
"Some migrants are able to build up spectacular populations in a very short time, far surpassing the density of sedentary species. In addition, they may avoid their normal predators, whose numbers cannot increase fast enough to take advantage of the temporary surfeit of potential prey. There was hardly any mortality due to parasites or disease among the more than 500,000 Caper Whites (Anaphaeis [= Belenois] aurota) which hatched in May 1981 in a wadi in Oman."
Watch those skies, as always!
