Extinct Australian palorchestid marsupials, new research


This February 2018 video says about itself:

This week, we’ll be exploring the rise and fall of the incredible megafauna that used to roam Australia; from 3m tall kangaroos to giant wombats. We’ll discover how just one species of small marsupial evolved and radiated to create an ecosystem of giants.

From PLOS:

Ancient Australia was home to strange marsupial giants, some weighing over 1,000 kg

Extinct palorchestid marsupials likely filled a niche no longer occupied in modern Australia

Palorchestid marsupials, an extinct group of Australian megafauna, had strange bodies and lifestyles unlike any living species, according to a study released September 13, 2019 in the open-access journal PLOS ONE by Hazel Richards of Monash University, Australia and colleagues.

For most of the last 25 million years, eastern Australia was home to a now-extinct group of marsupials called palorchestids. These animals are well known for their large size, strange tapir-like skulls, and large claws, but so far there has been no detailed study of their limb morphology. In this study, Richards and colleagues examined more than 60 fossil specimens of palorchestids of varying geologic ages to characterize the function and evolution of their arms and legs.

Over the course of their evolution, palorchestids grew larger and stranger. Using limb proportions as a proxy for body size, these authors estimated that the latest and largest of the palorchestids may have weighed over 1,000kg. Furthermore, their forelimbs were extremely muscular and were likely adapted for grabbing or scraping at leaves and branches. Uniquely among known mammals, the elbow joints of the largest palorchestids appear to have been immobile and fixed at roughly a 100-degree angle, so that the arms served as permanently flexed food-gathering tools.

This study provides the first formal description of limb morphology in palorchestid marsupials and reveals a group of giant herbivores that probably filled a niche no longer occupied in modern Australian ecosystems. Fossil remains are still missing for certain parts of the palorchestid body, such as the shoulders and wrists, but the authors are hopeful that more material may be found in existing museum collections.

The authors add: “This study has allowed us for the first time to appreciate just how huge these mega-marsupial palorchestids were, while also providing the first comprehensive view of a strange limb anatomy unprecedented in the mammalian world. This research reveals yet more about the diversity of unique large marsupials that once roamed Australia not so long ago.”

Female Trinidad guppies save males from starvation


This 3 September 2018 video says about itself:

This video gives an impression of the fieldwork we conduct to study guppy behavior in the rainforest of Trinidad. It also summarizes the main conclusions of our scientific paper in Nature Ecology and Evolution, which examines how being social helps guppies find food.

Reference to Paper: Snijders L, Kurvers RHJM, Krause S, Ramnarine IW, Krause J (2018). Individual- and population-level drivers of consistent foraging success across environments. Nature Ecology and Evolution.

From Forschungsverbund Berlin in Germany:

Male Trinidad guppies find food thanks to females

September 13, 2019

For male Trinidad Guppies applies: if you are hungry, seek female company. A recent study led by scientists of the the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) and the Leibniz Institute for Zoo and Wildlife Research (IZW) together with other research institutions provides evidence that male guppy fish in the presence of females more often ended up at novel food patches. In contrast, female food discovery was independent of male presence.

Trinidad guppies (Poecilia reticulata) live in small watercourses in the rainforests of Trinidad. They have a preference for sporadic high-quality food resources, like fruits and insects, falling into the water- so it is usually uncertain when and where they encounter food. In this study, behavioural ecologist Lysanne Snijders and her team set up a field experiment and manipulated guppy sex compositions (all male, all female or mixed) in the wild using individually colour-marked guppies. They conducted social observations, followed by foraging trials.

Males reached more food patches when there were females around. Yet, females reached a similar number of patches either with or without males present. Males also spent less time social in absence of females, but the absence of males had no effects for females. The researchers analysed if this time spent socially was linked to patch discovery success. Indeed, in agreement with a previous study, more social guppies ended up at more food patches.

“Life in the group can be advantageous. You have to share the food with your peers, but it is also easier to find it if you use the information of others,” explains Lysanne Snjiders. Guppies, for example, react to the typical behaviour of successful food finders, which is: swim faster, grab food, stay there and eat.

The researchers can only guess why males behave differently in the absence of females than in sexually mixed groups. “In this case, males among themselves are more likely to be in a state of competition than cooperation and therefore spend less time together and miss out on important information,” says Lysanne Snijders.

The head of the study, IGB-researcher Prof. Jens Krause, is investigating the dynamics of swarm behaviour and collective intelligence in animals. He explains the importance of this field of research: “If we are able to understand the interactions of animals within a group, we can derive from this knowledge information about the spread of diseases, reproduction and predator-prey relationships. The structure of social networks may also be a decisive factor concerning the stability of a population. Such knowledge may help wildlife managers and conservationists, for example, to optimise disease management, breeding programmes or reintroduction activities.”

Guppies, a perennial pet store favorite, have helped a UC Riverside scientist unlock a key question about evolution: Do animals evolve in response to the risk of being eaten, or to the environment that they create in the absence of predators? Turns out, it’s the latter: here.

Leadership during cooperation runs in the family for tiny fish called Trinidadian guppies, new research shows. University of Exeter researchers studied leadership in guppies by selectively breeding for fish that differed in how likely they were to lead a scouting party to examine a predator: here.

Yellow-billed loons in love, video


This video from the Cornell Lab of Ornithology in the USA says about itself:

The Yellow-billed Loon is the largest and most spectacular of the world’s five loon species. It breeds around the globe in arctic and sub-arctic tundra lakes and is the northern counterpart to the Common Loon.

Watch this rare video shot by The Lab’s Gerrit Vyn of a mated pair calling and foraging just after arriving on the partially frozen breeding grounds in Chukotka, Russia.

Central America critical for migrating birds


This January 2015 video says about itself:

US Bird Count Shows Climate Change Affecting Migration Patterns

Thousands of birdwatchers in the United States, Canada, Latin America and the Caribbean were out in force from mid-December to the beginning of January (December 14-January 5) counting birds. They took part in the 115th “Christmas Bird Count”, sponsored by the National Audubon Society, a U.S. bird conservation organization. Data collected from the annual event is helping scientists understand how environmental changes affect birds. VOA’s Deborah Block joined a group of birdwatchers in the wetlands at Mount Vernon, Virginia -the famous home of the first U.S. president, George Washington.

From Oxford University Press USA:

Conservation of a Central American region is critical for migrating birds

September 12, 2019

Many of North America’s migratory birds are declining, but the mysteries about when and how birds migrate must to be solved to effectively protect them. A new paper in The Auk: Ornithological Advances, published by Oxford University Press, identifies a previously overlooked area that is critical for conservation: the region between southern Mexico and Guatemala where songbirds fuel up for a grueling flight across the Gulf of Mexico.

Migration is a dangerous time for birds, especially during flights over large bodies of water. Many birds migrate directly across the Gulf of Mexico, requiring over 600 miles of sustained flight. The details of how the survivors manage this feat of endurance have been murky, especially for species like warblers, whose small size prevented researchers from tracking their full migration routes until recently.

Researchers used light-weight geolocators to identify migration strategies for the vulnerable and declining Golden-winged Warbler, finding 80% of individuals spent a week in southern Mexico and Guatemala to feed and build up reserves for the flight over the Gulf of Mexico in spring migration. The importance of this stopover region was previously unknown for this species, and it needs conservation given the rapid conversion of natural habitats to pasture and farmland.

While most Golden-winged Warblers stopped in this region, not all did. Some that overwintered in northern Central America were able to make the trans-Gulf flight directly from their overwintering grounds without the stopover. “This is an important finding,” says Dr. Ruth Bennett of the Smithsonian Migratory Bird Center, “because birds that migrated directly across the Gulf were able to shave a week off their total migration time. These birds may experience a selective advantage in the spring.” That is because male Golden-winged Warblers race north in spring migration to establish breeding territories. Results from the study suggest the spring period requires more energy and poses a greater risk of predation and starvation, while fall migration allows for more flexibility to minimize energy costs and avoid risks.

“The variation we describe in migration routes and stopovers is encouraging,” says Bennett. “Variation helps buffer a population from local changes in environmental conditions.” Now that authors have identified where and when Golden-winged Warblers prepare for migration, they can start identifying the habitats that best allow birds to fuel up and successfully cross the Gulf of Mexico. This study provides a critical piece of the larger puzzle about where, when, and how to best protect the declining Golden-winged Warbler and other North American migratory birds.

A study published today in the journal Science reveals that since 1970, bird populations in the United States and Canada have declined by 29 percent, or almost 3 billion birds, signaling a widespread ecological crisis. The results show tremendous losses across diverse groups of birds and habitats — from iconic songsters such as meadowlarks to long-distance migrants such as swallows and backyard birds including sparrows: here.