Fairy wrens and their relatives (Maluridae) as model organisms in evolutionary ecology: the scientific legacy of Ian Rowley and Eleanor Russell
Theornithologist, publisher and entrepreneur JohnGouldwas the first to hint at the truly remarkable complexity of the behaviour of fairy wrens (Malurus spp. (Gould 1840 1848) In his published lithograph of Superb Fairy wrens (Malurus cyaneus) he shows three adults attending a nest (Fig. 1) Two brilliantly coloured males are both carrying food to the nest, watched by a single dull brown female. However, the males are being duped, for the chick poking out of the nest is not their own offspring, but a bronzecuckoo (Chalcites sp. brood parasite. This early lithograph encompasses much of the fascination that has endured with this group as well as virtually all the themes addressed in this special issue on the family of fairy wrens Maluridae: sexual signalling, cooperative care of nestlings and the evolutionary paradox that male fairy wrens often care for young that are not their own. Most accounts of Malurus fairy wrens by early European naturalists alluded to the possibility that they were cooperative breeders (Boland andCockburn 2002) the social system inwhich more than two birds share the task of raising a brood of young. Indeed, the fact that fairy wrens are cooperative breeders seems to have been common knowledge decades before the behaviour was supposedly 'discovered' by Alexander Skutch (Rowley 1957, Skutch 1961) the great student of neotropical ornithology. In hindsight, it is easy to see why cooperative breeding, which is now known to occur in ~10% of bird species (Cockburn 2006) and is particularly prevalent in the Australian avifauna, was so obvious in fairy wrens. They typically build nests close to the ground, and some species adapt well to gardens, so their nests are easy to find and often easily observed by amateurs and professionals alike. In addition, and in contrast to most cooperatively breeding species where males and females are essentially monomorphic (Stacey and Koenig 1990) the pronounced sexual dimorphism in fairy wrens and frequent attendance at the nest of two breeding plumaged bright males, makes cooperative behaviour straightforward to detect. However, although cooperative breeding was identified, it attracted little attention for much of the twentieth century, nor was there any real conceptual explanation as to whymales and females in these species were so strikingly different in plumage. We owe the formal documentation of cooperative breeding in fairy wrens to a technique that is now so commonplace, that it seems astonishing that it was not attempted in cooperative species until the 1950s. This revolutionary method involved attaching unique combinations of coloured plastic rings to the legs of birds so they could be individually identified (Rowley 1957; Bradley and Bradley 1958) It was CSIRO scientist Ian Rowley who developed this method withMalurus as a side project while working on rabbit control in Canberra. He used colour ringing of the birds near the CSIROGungahlin laboratories to analyse their behaviour in unprecedented detail, culminating in one of themost influential papers (Rowley 1964) ever published in Emu. Indeed, that paper is currently the most highly cited paper from the entire archive of Emu Austral Ornithology. Ian was then directed by CSIRO to investigate the effect that crows and ravens (Corvus spp. have on sheep. This similarly distinguished work of his clarified the taxonomy and ecology of the Australian Corvus resulting in recognition of two further Australian corvid species: Little (C. mellori) and Forest Ravens (C. tasmanicus) However, he found that he often caught groups of White winged Choughs (Corcorax melanoramphos) in his corvid traps, enabling him to conduct another classic studyon cooperative breeding in this very different species (Rowley 1978) This research experience placed him at the forefront of attempts to understand cooperative breeding and at a time when the behaviour had attracted new interest worldwide. Not only had several long term field studies commenced, but cooperative behaviour had assumed centre stage as a 'problem' in the newly founded discipline of behavioural ecology. That endeavour had rejected the naive arguments proposed by Alexander Skutch and many others that cooperative breeding was a form of reproductive restraint that operated for the good of the species (Skutch 1961) New ideas concerning the benefits of investing in kin were starting to take hold. Ian then moved to the CSIRO laboratories in Western Australia to examine the effect of the most familiar Australian cockatoo, the Galah (Eolophus roseicapillus) on agriculture. Once again, this led tomore classicwork (Rowley 1990) but also brought Ian into close contact with a new and diverse group of fairy wrens. Eventually, he conducted work on five of the Western Australian Malurus species (Rowley et al. 1988, 1991; Rowley 1993; Rowley and Russell 1995, 2002) initiating a long termstudyon theSplendidFairy wren (Malurus splendens) SPECIAL ISSUE