Our review of extrapair paternity in birds is published today in Molecular Ecology and can be accessed here. The paper, written by Lyanne Brouwer and myself, is an update on the last review that I published on the subject in 2002. There are now over 30 years of molecular data on the incidence of extrapair offspring in socially monogamous species and we present an overview of over 500 studies focused on over 300 species. Overall, in around three quarters of socially monogamous species, some evidence of infidelity has been found. In the species in which it occurs about one fifth of all offspring are fathered by an extrapair sire, and therefore not by the social male who is investing in their care. We also demonstrate that the incidence of extrapair paternity is more likely to occur in some avian families, being particularly prevalent in passerines, and rarer, or completely absent in families that are long-lived, such as owls, or seabirds.
Our new paper has just come out, from work done at Fowlers Gap a couple of years ago. In the study we looked at how nestlings are affected by both very hot days and very windy days as they are developing in the nest. These conditions are stressful for nestlings, and we found that both types of bad weather affected the level of corticosterone – the stress hormone. These findings are likely to be driven both directly and indirectly. When nestlings are very hot, they find it hard to lose heat and that will be stressful itself. Wind can be stressful because the noise will mask the ability to hear other sounds in the environment, such as communication with parents, and also the noise of approaching predators. In addition, the results may be the indirect effect of hunger, as parents will find it much more difficult themselves to find food to feed to their nestlings when it is hot and windy. The work was led by Ondi Crino, who is an endocrinologist, and expert on stress. The paper can be found here.
In the second paper to be published from Hanja’s thesis, we have demonstrated that zebra finches would rather nest next to a pair that are also just starting to breed, than a pair that is further along. Hanja and team demonstrated this by erecting new empty nest boxes near to occupied boxes, at either nest-building, incubating or chick rearing stages. Pairs were far more likely to lay eggs in the experimental boxes that were close to those that had also initially been at the nest building stage. We believe that these results are driven by the social benefits of breeding alongside other pairs at a similar stage of activity. The paper is published in the journal Animal Behaviour, and can be downloaded for free in the next month using this link.
A paper by student Victoria Austin, completed while she was an MRes student in the lab has just been published, focused on the almost incessant singing of the chirruping wedgebill – a song that will be familiar to anyone who has worked at Fowlers Gap, or elsewhere in the range of this arid zone bird. The paper, entitled ‘Song rate and duetting in the Chirruping Wedgebill (Psophodes.cristatus): frequency, form and functions’ has been published in Emu – Austral Ornithology. The paper can be found here.
Even though it was extremely dry at Fowlers Gap this spring, our zebra finch field season was a successful one. Luckily for us, zebra finches were still present in large numbers despite the drought. Interestingly, zebra finches were still found singing actively although hardly any breeding attempts were made.
In a new collaborative project with Marc Naguib and Hugo Loning of Wageningen University, the Netherlands, we will look into more detail at wild zebra finches’ communication, especially singing behaviour. From lab studies we know that their song functions in mate choice when reaching maturity, but why they sing for the rest of their adult life remains unclear.
To this end we have installed a large number of passive acoustic monitoring devices which enables us to monitor the acoustic environment during and outside of breeding seasons, in a variety of habitats for years to come. This will not only contribute to zebra finches studies, but also gives us valuable information on the presence of other birds, which will benefit additional studies on bird ecology, migration and conservation in these unpredictable, extreme environments.
Our paper on genetic changes in response to Lead pollution in the outback towns of Broken Hill (NSW) and Mount Isa (Queensland), has been published in the journal, Science of the Total Environment. The paper, “Signs of adaptation to trace metal contamination in a common urban bird” focuses on changes in the frequency of 35 SNP’s linked to a number of genes, some of which have been shown to relate to the transfer of heavy metals across cell membranes.
The study, led by Sam Andrew, and part of his PhD project was done in collaboration with the team in Trondheim led by Henrik Jensen, and also Mark Taylor at MQ.
The study was covered by a few stories in the media and one of those stories can be found here. The article itself can be accessed here.
In September we conducted fieldwork on either side of the NT and WA border to sample long-tailed finches in the area where the eastern and western forms of the Z chromosome meet in the wild (see recent paper by Hooper et al (2018). The fieldwork team comprised Daniel Hooper and Emma Grieg (both from Cornell University), Kyle Kostrzewa, and Callum McDiarmid and Simon Griffith (Macquarie). The trip was successful and we had two weeks of camping, driving (a lot) and finding water holes and sampling birds in the area from Keep Rive in the east, to Home Valley station in the West.
Simmons et al (2011) False-Positive Psychology: Undisclosed Flexibility in Data Collection and Analysis Allows Presenting Anything as Significant. Psychological Science 22 1359–1366 https://DOI:10.1177/0956797611417632
Wang et al (2018) Irreproducible text-book “knowledge”: The effects of color bands on zebra finch fitness. Evolution https://doi:10.1111/evo.13459
Babbler and zebra finch fieldwork is underway at Fowlers Gap again in what is shaping up to be the worst drought since our work began out there in 2004. The long-term average amount of annual rainfall at Fowlers is 235mm. Since September 2016, there has been a total of 181mm across 23 months. In 2017 there was a total of just 77mm which makes it the second driest year from the 60 years for which data is available (Data from Bureau of Meteorology). So far, 2018 is looking even worse, with less than 3mm of rain recorded in the first seven months of the year.
As illustrated above, the environment is already looking extremely dry and the heat is just starting to pick up in the late winter, which will further dry the environment and challenge the animals and plants at the research station. Not surprisingly, in the work to date, there is no evidence that any of the birds are starting to breed, and the whole landscape is in urgent need of a drink.
Our recent work investigating the effects of the southern hemisphere climatic oscillations La Niña and El Niño on the timing of breeding by 64 temperate breeding species, and 15 species breeding in the arid zone. As illustrated below, La Niña is characterised by milder wet conditions in the main avian breeding period, and in such years, egg laying periods were typically longer for most species. There was a lot of variation in the response of different species and partly this was related to whether they breed early in spring. We found no obvious adverse effect of dry La Niña conditions, contrary to a prior expectation.
This study represents the most intensive examination of the effect of the southern climatic oscillation on breeding phenology in Australian birds and is focused on over 80,000 breeding records collected by a wide variety of sources over the past century.
Sam’s paper characterising the structure of the house sparrow populations across Australia and New Zealand, was recently published in Biological Invasions.
The main conclusion of this work is that the population genetic structure of the house sparrows across Australia and New Zealand today, largely reflects the historical introductions of these populations, that were founded by deliberate introductions in the 1850-60s, by the Acclimatization Societies that were active in New Zealand, and multiple cities across Australia. As well as confirming the historical records concerning the site of independent introductions, the strong structure that we have characterised suggests limited movement between many populations. This is interesting because it provides the opportunity for selection to act on contemporary populations fairly independently and local adaptation may result, particularly given the range of climates and ecological variation faced by the different populations.
Andrew SC, Awasthy M, Bolton PE, Rollins LA, Nakagawa S, Griffith SC, (2018) The genetic structure of the introduced house sparrow populations in Australia and New Zealand is consistent with historical descriptions of multiple introductions to each country. Biological Invasions, 6, 1507-1522.