Impact of invasive little fire ants Wasmannia auropunctata on rainforest soil fauna: implications for conservation of the endangered flightless kagu of New Caledonia

International audienceThe little fire ant, Wasmannia auropunctata , is an invasive species known to negatively affect many native species in its introduced range. Here, we studied the effect of little fire ant presence on the biomass of soil fauna in rainforest of New Caledonia to assess if little fire ants have an impact on an endangered endemic flightless bird, the kagu, Rhynochetos jubatus. The average biomass of soil fauna (except for millipedes) was lower in 53 sample plots with little fire ants than in 597 sample plots without little fire ants and the biomass decreased with increasing density of little fire ant nests. Millipedes on the contrary seemed to be positively impacted as their average biomass was higher in areas with fire ants than in areas without, but even millipede biomass decreased with increasing nest density of fire ants. Kagu density decreased with increasing area of rainforest invaded by little fire ants, suggesting, given their observed negative impact on soil fauna biomass, that they may limit food resources for kagu. Little fire ants might therefore transform rainforest into a less suitable habitat for the kagu by reducing the biomass of their prey and thus have a negative impact for kagu conservation

Parrots of Oceania - a comparative study of extinction risk

Australia, New Zealand, New Guinea, Wallacea, and the islands of the Pacific Ocean collectively possess 42% of the world’s parrot species, including half of all Critically Endangered species. We used comparative methods to review the factors related to extinction risk of 167 extant and 5 extinct parrot species from this region, subsequently referred to as ‘Oceania’. We tested a range of ecological and socio-economic variables as predictors of extinction risk for parrots in the region while controlling for phylogeny. Parrot species were most likely to be threatened if they had small historical ranges, large bodies, or a high dependency on forest, or if they were endemic to a single country, or native to a country with high unemployment. Our analysis identifies invasive species as an especially severe threat to the parrots of Oceania. We present maps of parrot species’ diversity and draw attention to regions of conservation concern. Our comparative analysis presents an important overview of the factors contributing to the decline of parrots in Oceania, and provides a strong basis for comparison with other parts of the world.This research was funded by the Australian Research Council, Loro Parque Fundación, the Australian Government National Environmental Science Programme via the Threatened Species Research Hub and the Department of Education and Training of the Australian Government via an Endeavour Postdoctoral Research Fellowship (ERF-PDR-6086-2017) to George Olah

Polymorphism at the nestling stage and host-specific mimicry in an Australasian cuckoo-host arms race

Decades of research have shown that the coevolutionary arms race between avian brood parasites and their hosts can promote phenotypic diversification in hosts and brood parasites. However, relatively little is known about the role of brood parasitism in promoting phenotypic diversification of nestlings. We review field data collected over four decades in Australia, New Caledonia and New Zealand to assess potential for coevolutionary interactions between the shining bronze-cuckoo (Chalcites lucidus) and its hosts, and how diversification at the nestling stage may be generating different subspecies. The shining bronze-cuckoo is a specialist parasite of a few hosts in the family Acanthizidae. It has diversified into subspecies, of which the nestlings closely mimic the respective host nestlings in each region. Additionally, some cuckoo subspecies have polymorphic nestlings. The Acanthizidae hosts have similar breeding and nesting habits and only moderately effective frontline defences against parasitism at cuckoo egg laying or at the egg stages. However, some hosts have developed highly effective defences at the nestling stage by recognising and ejecting cuckoo nestlings from the nest. As with the cuckoo nestlings, some hosts have polymorphic nestlings. The coevolutionary interactions in each region suggest different evolutionary stages of the arms race in which either the parasite or the host is currently in the lead. The presence of moderately effective defences at the egg laying and egg stages might explain why some hosts do not have defences at the nestling stage. The south-Pacific cuckoo - host systems are excellent models to explore the evolutionary mechanisms driving the diversification at the nestling stage in the coevolutionary arms race between avian brood parasites and their hosts.Peer reviewe

Austral birds offer insightful complementary models in ecology and evolution

Theuerkauf J, Villavicencio CP, Adreani NM, et al. Austral birds offer insightful complementary models in ecology and evolution. Trends in Ecology & Evolution. 2022;37(9):759-767.The Southern Hemisphere differs in many aspects from the Northern Hemisphere. However, most ecological and evolutionary research is conducted in the Northern Hemisphere and its conclusions are extrapolated to the entire globe. Therefore, unique organismal and evolutionary characteristics of the south are overlooked. We use ornithology to show the importance of including a southern perspective. We present examples of plumage pigmentation, brood-parasitic nestling ejection, flightlessness, female song, and female aggression modulated by progesterone as complementary models for investigating fundamental biological questions. More research in the Southern Hemisphere, together with increased cooperation among researchers across the hemispheres and within the Southern Hemisphere, will provide a greater global outlook into ecology and evolution