Why Arebulbuls Doing So Well?

ANIMAL DEMOGRAPHY UNIT WHY ARE bulbuls DOING SO WELL? If you anticipate a definitive answer at the end of this piece, you are going to be disappoint- ed. Like so many things hap- pening with our birds, we don’t know exactly why. But we have some ideas. ne of the unexpected outcomes of SABAP2 is that, of all bird families, it is the bulbuls that are doing the Obest. They are the gold medallist of the 79 families that entered this race. What are the rules of this event? How does one ‘score’, and how is the winner determined? The score is the average amount of green and blue in the range-change map comparing SABAP1 and SABAP2 distributions for all members of the family. In the accompany- ing map for Dark-capped Bulbul, the blue quarter-degree grid cells represent the new range for the species since SABAP1. In the vast number of green cells, the species is being recorded more frequently in SABAP2 Pycnonotidae and they occur in Africa and partly a consequence of land-use change and than it was in SABAP1. This is measured southern Asia. One bulbul has achieved no- partly a result of a carbon dioxide-enriched through the reporting rate, so it removes toriety: the Red-vented Bulbul, native to India, atmosphere, which is thought to favour to a large extent the effect of number of has been introduced to many countries, even the growth of trees and shrubs over that of checklists per cell. Orange cells reflect a New Zealand, and it is listed by the IUCN as grasses. In addition, much marginal arable lower reporting rate now, and in red cells the one of the world’s 100 worst invasive species. land has been abandoned in many areas, and species appears to have gone extinct (it was Most species in the family have a diet that regrowth is taking place. Over parts of the recorded there in SABAP1 but not in SABAP2). consists mainly of fruit, which they augment arid west, dry watercourses are becoming Being the winner of this event means that, with seeds, nectar, pollen, insects, spiders and lined with riverine bush. Orchards, gardens among all families, the bulbuls show on the occasional lizard. They are opportunistic and farmyards are good news for bulbuls. average more green and blue than any other. and catholic in their diet. The Terrestrial Detailed studies are now needed to uncover For the record, the green and blue scores for Brownbul scratches in leaf litter and eats the real reasons why the bulbuls are doing so the six Pycnonotidae with substantial ranges mostly arthropods and some fruit. In terms well, and separate reality from hypothesis. are Yellow-bellied Greenbul 71.5 per cent, of habitat, most live in forest, savanna, scrub The silver and bronze medallists are the Cape Bulbul 69.5 per cent, Sombre Greenbul and thickets. Most species do well in second- cisticola family and the weaver family; the 66.9 per cent, Dark-capped Bulbul 61.7 per ary regrowth. Wherever human transforma- same conditions that favour the bulbuls are cent, Terrestrial Brownbul 55.0 per cent, and tion results in scrubby or thicketed habitats, generally also favourable to these. The next African Red-eyed Bulbul 52.9 per cent. The the bulbuls soon colonise it. article in this series will focus on the families bulbul in fourth place out of the six is the This is probably the clue as to why the which came last in this event, the wooden- one being used to illustrate the point, so no bulbuls in general are doing so well in the spoon awardees. It makes salutary reading. sleight of hand here! original SABAP2 region of South Africa, SABAP2 continues to deliver fascinating Bulbuls, somehow, are not charismatic Lesotho and Swaziland. One of the ecolog- results. If you are not yet an atlaser, please birds and have seemingly been neglected by ical processes taking place across this region consider becoming involved in this critically ornithologists. There are 138 species in the is a general thickening of vegetation. This is important project. ANIMAL DEMOGRAPHY UNIT • University of Cape Town, Rondebosch 7701, South Africa • Tel. +27 (0)21 650 2423 • e-mail [email protected] • www.adu.org.za JULY/AUGUST 2013 ANIMAL DEMOGRAPHY UNIT 25.

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