Preening power: red-billed woodhoopoes go on the defensive

The Red-<strong>billed</strong> Woodhoopoe Phoeniculuspurpureus is an intriguing species.Because it lives in groups, itssociety is a rich tapestry of inter actions,alliances, betrayals and secrets. Its life isplayed out in the forests and woodlandsof sub-Saharan Africa, where it is one ofthe more conspicuous birds. Its noisycalls echo and resound across valleys,while territorial disputes between neighboursachieve impressive crescendos. Onewould struggle not to see these birdswhen walking through any reasonablylarge tract of forest or well-wooded habitat.The species’ raucous cackling givesrise to its Xhosa name, Hlekabafazi, whichmeans ‘laughing women’.For almost 30 years biologists havebeen studying these somewhat bizarre,but ingratiatingly endearing birds. Theirintricate lives are unique among birdsin a number of ways and, despite animpressive volume of research, theycontinue to surprise.An unusual strategyOne of the Red-<strong>billed</strong> Woodhoopoe’smore unusual traits is its need to roostin cavities (usually in trees), a situationcomplicated by the fact that the birdscannot excavate their own holes. Thisreliance on other animals’ (or nature’s)handiwork places them under tremendouspressure. In many areas, thereis enormous competition between severalcavity-roosting species, and <strong>woodhoopoes</strong>are always on the lookout for aback-up cavity in their territory.Woodhoopoes breed communally. Inmost recorded cases of breeding attempts,the alpha pair breed, and any other membersof the group help in the rearing ofthe brood. The business of helping othersto raise young rather than breeding oneselfis quite intriguing. At first glance itmight not make much sense to expend alot of time and energy helping to rearanother pair’s young. Why don’t thesehelpers <strong>go</strong> off and breed themselves?Firstly, some year-old birds do manageto establish territories and breed. Theirsuccess rate is, however, generally ratherlow. By contrast, helpers seem able tolearn what to do, and when they establishthemselves as breeders, they tend todo much better than others. It takes a lotof practice and skill to forage in thewoodlands for oneself, let alone for aChris van rooyenLeft and right Communalliving has advantages for the<strong>woodhoopoes</strong> – increased numbersmean a better defence systemand more helpers to feedthe young.brood of highly demanding, growingchicks. A second reason is that moreoften than not, helpers are ‘family’; eitheroffspring from earlier breeding attemptsor related (typically siblings) to one of thealpha pair. It makes biological sense toinvest in one’s family, even if the youngbeing ca<strong>red</strong> for aren’t one’s own. Becauseof this ‘blood connection’ or relatedness,helpers invest their efforts in ensuringthat their sha<strong>red</strong> genes are passed on tothe next generation. This co-operativebreeding strategy is employed by a diversityof animals, ranging from honey-beesand ants to naked mole-rats.A third reason is that in some circumstancesroosting cavities and territoriesare hard to come by, and even harder todefend. A larger group can usually defenda cavity or maintain a large territory, andwhen times are tough, for example intimes of drought, territories are oftenexpanded to improve foraging. Underthese circumstances, small groups runthe risk of being displaced completely.This can be an utter disaster for <strong>woodhoopoes</strong>,which have to find safe roostingcavities every night. It seems thatthe best option, unless another territorycan be found immediately, is to joinanother group.The disadvantage of joining anothergroup is that newcomers always start atthe bottom of the ladder. A very strongpecking order is present in most grouplivingbirds and in <strong>woodhoopoes</strong> thistakes on added significance. Should oneof the alpha pair die, the male or femalenext in line in the pecking order willtake over as breeders. For newcomersthis can mean a very long wait for thechance to reproduce.Threats from p<strong>red</strong>atorsNo one is really too sure why <strong>woodhoopoes</strong>always roost in a cavity. Some evidencesuggests that during winter, grouphuddling in cavities can result in a considerablesaving of energy. This does notexplain why, on warm nights, cavi- Brendan Ryan56 <strong>red</strong>-<strong>billed</strong> WoodHoopoesfebruary/march 2001<strong>red</strong>-<strong>billed</strong> WoodHoopoes57