Robert Montgomerie

Group-living social systems are common in nature, but the adaptive benefits of these social systems and how they relate to mating systems have not been well studied. White-winged Fairywrens have one of the most complex and enigmatic avian social systems. Group territories are occupied and defended by up to 20 adults in brown plumage and 1 adult male in ornamented plumage (vivid blue and white on mainland Australia; black and white on 2 islands off the west coast), with up to 5 pairs breeding on each group territory, often with assistance from helpers. The adaptive benefits of this social structure and how it relates to the species’ mating system have not been studied. Here we present a field study of 2 populations (1 island, 1 mainland) during 2 consecutive breeding seasons in which we documented the social structure of adults and quantified the genetic relationships between 205 adults, 34 juveniles, and 158 nestlings. First- and second-order kin relationships between adults were more commonly observed across group territories than within, and although more than 70% of nestlings were sired by extrapair males, most extrapair sires were from outside of the social group territory. When social mates were first- or second-order kin, extrapair males were almost always unrelated, and extrapair males tended to be in better condition than the pair males they cuckolded. Our results do not clearly support previously suggested hypotheses (kin selection or cuckoldry) for this species’ complex social structure. The functional benefits of this social system remain enigmatic.

Spermatogenesis is a temperature-sensitive process, but previous studies on seasonal variation in semen quality have produced conflicting results, often du

We evaluate whether a Neolithic engraved rock image at the Alta archaeological site in Finnmark, Norway – of a bird being held by a person – represents a Great Auk Pinguinus impennis. There are several thousand engraved animal figures at Alta, created between 5000 and 2000 years ago, in various hunting panoramas. Of these images, 24 represent aquatic birds, including four others that might also be Great Auks. Based on the size of the bird relative to the person holding it, the size and shape of the beak, wings and webbed feet, and comparisons with some other bird images at Alta, we conclude that it is likely that this one does represent a Great Auk.

The body mass and egg mass of the Great Auk Pinguinus impennis were never measured before the bird was driven to extinction in 1844. Previous studies conducted before 1990 used data from related species to estimate the mass of an adult bird at 4500–5000 g, and the fresh mass of its egg as 327–372 g. In the present study, we use a larger dataset of measurements from extant alcids, and statistical methods that control for the effects of phylogeny, to provide new estimates for those traits. The presumed body mass of the Great Auk was initially derived from a hearsay report from the 19th century, and then supported by subsequent comparative analyses based on skeletal measurements. Our new best estimates from currently available data show that the Great Auk's body mass was probably closer to 3560 g and its fresh egg mass was about 350 g. This new body mass estimate is the average of predictions from independent regressions of body mass on (1) tibiotarsus and femur lengths (3441 g) and (2) egg volume (3681 g). We calculated the Great Auk's fresh egg mass from a regression of fresh egg mass on egg volume in the extant alcids. Providing more accurate estimates of the body and egg mass of Great Auk can inform speculation about the developmental mode, ecology and life history of this iconic, extinct species.

Has there been variation in semen quality among men applying to be sperm donors (i.e. donor candidates) in Denmark in recent years (2017–2022)? The motile sperm concentration and total motile sperm count (TMSC) in ejaculates—both measures of sperm quality—declined by as much as 22% from 2019 to 2022. Questions remain about whether human semen quality has declined in recent years. Whilst some studies provide evidence for a decline in human semen quality, these findings have been disputed owing to potential biases in the populations studied or in the methods used to measure semen quality. Resolution of this issue has important implications for human fertility, as well as for those involved in the recruitment of sperm donors for use in medically assisted reproduction. We obtained data on the semen quality of ejaculates previously collected from 2017 to 2022 at sperm bank locations in four cities in Denmark: Aarhus, Aalborg, Copenhagen, and Odense. Our study focuses on the single semen samples provided by 6758 donor candidates aged between 18 and 45 years old to determine whether their sperm quality met a minimum criterion for them to be accepted as sperm donors. All ejaculates were analyzed within 1 hour of production. Semen volume (ml) was estimated by weight and both the concentration (10⁶/ml) of sperm as well as the concentration of motile sperm (World Health Organization grades a and b) were measured using the same protocols and computer-assisted semen analysis system across all years at each site. Statistical analyses of the semen variables were controlled for age and donation site, as well as the average monthly high temperature when the ejaculate was produced. From 2017 to 2019, semen volume, sperm concentration, and total sperm count in the ejaculates of donor candidates increased by 2–12%. Then, from 2019 to 2022, sperm concentration and total sperm count changed by 0.1–5% from year to year, but none of those changes were statistically significant. In contrast, both motile sperm concentration and TMSC declined significantly, by 16% and 22%, respectively, between 2019 and 2022. Thus, the concentration of motile sperm in donor candidates declined from 18.4 [95% CL: 17.0, 20.0] million/ml in 2019 to 15.5 [14.4, 16.7] million/ml in 2022, and TMSC declined from 61.4 [55.8, 67.5] million per ejaculate in 2019 to 48.1 [44.1, 52.4] million in 2022. We cannot determine from the available data the causes of the decline in semen quality of donor candidates from 2019 to 2022. However, as this period coincides with lockdowns and changes in work patterns during the coronavirus disease 2019 pandemic, it is possible that changes in motile sperm concentration and TMSC were the result of changes in the lifestyles of the men whose semen was analyzed. Men providing initial semen samples at sperm banks, when applying to be sperm donors, are a useful population in which to monitor changes in human semen quality over time. Our results have implications for human fertility and the recruitment of sperm donors for medically assisted reproduction, where motile sperm concentration is an essential selection criterion because it influences fertility. We suggest that gathering health and lifestyle data on donor candidates at sperm banks might help to identify causal factors for the decline of sperm quality that could be addressed and intervention, if desired, could be personalized for each accepted donor. No external funding was obtained for this study. E.L. and A.-B.S. are employees of Cryos International. AP reports paid consultancy for Cryos International, Cytoswim Ltd, Exceed Health, and Merck Serono in the last 2 years of this study, but all monies were paid to the University of Sheffield (former employer). AP is also an unpaid trustee of the Progress Educational Trust (Charity Number 1139856). RM declares support from Cryos International to present results of this research at ESHRE 2023. None of the authors were directly involved in the collection or physical analysis of semen samples. N/A.

Climate change has resulted in a marked advancement in the breeding phenology of many bird species. Since the timing of many monitoring programmes is based on calendar dates, changes in the timing of birds’ breeding seasons may result in a mismatch with the census period. Using data from a long-term population study of Common Murres (Uria aalge; Common Guillemots in Europe) on Skomer Island, Wales, together with simulations, we show that the 2-week advance in the timing of breeding in Common Murres between 1973 and 2020 has serious implications for the timing of census counts. We show that because censuses have traditionally been conducted during the same fixed calendar period each year, the size of the breeding population has been underestimated. We recommend that censuses of breeding seabirds be made relative to the median egg-laying date rather than on specific calendar dates. Since climate change has resulted in a widespread advance in the timing of birds’ breeding seasons in the northern hemisphere, our results may be relevant to Common Murres at other colonies, and to other bird species worldwide.