Search

Research on immune response in polar fauna is gaining great importance due to different scenarios of environmental change. Total leukocyte counts in blood smears are one of the most widespread practices and provide useful information about the health status of individuals. However, there is no methodological agreement for these analyses. Total leukocyte counts can be performed at ×400 magnification in optical microscopy using 10,000 erythrocytes for standardizing. However, counting such number of erythrocytes is costly and time-consuming. Here, we describe a new technique to simplify leukocyte counts in blood smears from Antarctic wildlife based on the number of microscope fields instead of the number of erythrocytes which reduces considerably the time spent. We have counted total leukocytes using both methods in the three penguin species of the genus Pygoscelis—Adélie (P. adeliae), gentoo (P. papua), and chinstrap penguin (P. antarcticus)—and four Antarctic mammal species: crabeater seal (Lobodon carcinophaga), leopard seal (Hydrurga leptonyx), weddell seal (Leptonychotes weddellii), and southern elephant seal (Mirounga leonina) for validation. Our results show a high correlation between the total leukocyte counts using 10,000 erythrocytes or 10 microscope fields for standardizing. These results show the reliability of the latter method for counting the total number of leukocytes in different species of birds and mammals saving time and effort., The study was funded by the Spanish Ministry of Economy and Competitiveness through projects CTM2011-24427, CTM2015-64720, and PID2019-108597 and by the Dirección Nacional del Antártico, Instituto Antártico Argentino (PICTA 2010-01).

This study summarizes the temporal variation, the relative contribution of each university, the research topics addressed, the taxonomic groups studied and the differences in author and its advisors’ gender in the 303 PhD theses on herpetology defended in Spain and gathered in Teseo© and Dialnet© between 1977 and 2020. The number of theses defended per year is around 7 with an upward trend. Complutense and Autonomous University of Madrid universities hosted the highest number of theses, followed by Barcelona and Valencia universities. The most addressed topic was morphology, biometry and anatomy, followed by physiology and histology, genetics and habitat selection. The most studied herpetofauna orders were Squamata and Anura and the families most tackled were Lacertidae, followed by Ranidae and Salamandridae. The most addressed species were native to Spain and without protection status, as opposed to those that were non-native or with protection status. The study of invasive species is very poorly represented. The number of PhD theses defended by men is higher compared to those by women (1.43:1), however, both genders show an upward trend in the number of theses. The results represent an approximation of the development, trends and interests pursued by herpetological research in Spain., Both authors have carried out this study without public or private funding.

This study analyzes the scientific literature published on penguins in Argentina between 1985 and 2019. It examines the characteristics and the temporal variation in the number of publications, the total number of authors, the percentage of participation of Argentine researchers, the species and region of study, as well as the research topics they address. The results show a tendency towards an increase in papers and studies of these birds, the total number of authors, and the participation of researchers belonging to Argentine research centers during the period analyzed. The most studied penguin species was the Magellanic Penguin (Spheniscus magellanicus), followed by the Southern Rockhopper Penguin (Eudyptes chrysocome) and the Gentoo Penguin (Pygoscelis papua). The most addressed research topics were foraging and diet, followed by reproduction and reproductive success, conservation and wildlife management, population dynamics and physiology and histology, which were carried out mainly in the Patagonian region and in the Malvinas Islands. The results help to understand the past, present and future state of scientific literature, which will strengthen decision-making on future research on penguins.

Sea turtles constitute a threatened group of fauna, thus to know caveats in their knowledge it is crucial to lead research efforts. The present study aims to analyse the scientific literature published on marine turtles in Cabo Verde by means of a biblio-graphic analysis. We analysed the temporal and geographical variation in the publica-tions, the number of authors and nationalities involved, and the extent of study of differ-ent research topics by species. The number of publications grew through the analysed time period (1979-2020), as well as the number of authors. The countries with the highest number of publications were Spain followed by Cabo Verde. Research areas of greater investigation effort were “Breeding and reproductive success”, followed by “Conservation and management” and “Population dynamics”. However, there were differences between species and islands. Most of the studies were conducted at Boa Vista, followed by Sal and Maio Islands. The most studied species was Caretta caretta. This analysis contributes to understand trends and caveats in sea turtle knowledge that could help guide future research lines in areas of particular concern.

Background Energy landscapes provide an approach to the mechanistic basis of spatial ecology and decision-making in animals. This is based on the quantification of the variation in the energy costs of movements through a given environment, as well as how these costs vary in time and for different animal populations. Organisms as diverse as fish, mammals, and birds will move in areas of the energy landscape that result in minimised costs and maximised energy gain. Recently, energy landscapes have been used to link energy gain and variable energy costs of foraging to breeding success, revealing their potential use for understanding demographic changes. Methods Using GPS-temperature-depth and tri-axial accelerometer loggers, stable isotope and molecular analyses of the diet, and leucocyte counts, we studied the response of gentoo (Pygoscelis papua) and chinstrap (Pygoscelis antarcticus) penguins to different energy landscapes and resources. We compared species and gentoo penguin populations with contrasting population trends. Results Between populations, gentoo penguins from Livingston Island (Antarctica), a site with positive population trends, foraged in energy landscape sectors that implied lower foraging costs per energy gained compared with those around New Island (Falkland/Malvinas Islands; sub-Antarctic), a breeding site with fluctuating energy costs of foraging, breeding success and populations. Between species, chinstrap penguins foraged in sectors of the energy landscape with lower foraging costs per bottom time, a proxy for energy gain. They also showed lower physiological stress, as revealed by leucocyte counts, and higher breeding success than gentoo penguins. In terms of diet, we found a flexible foraging ecology in gentoo penguins but a narrow foraging niche for chinstraps. Conclusions The lower foraging costs incurred by the gentoo penguins from Livingston, may favour a higher breeding success that would explain the species’ positive population trend in the Antarctic Peninsula. The lower foraging costs in chinstrap penguins may also explain their higher breeding success, compared to gentoos from Antarctica but not their negative population trend. Altogether, our results suggest a link between energy landscapes and breeding success mediated by the physiological condition. Supplementary Information The online version contains supplementary material available at 10.1186/s40462-021-00255-9.