Songbirds singing together, new study


This 2015 video says about itself:

Australian Magpie-lark (Peewee) (Grallina cyanoleuca) tweeting away with a barking dog providing accompaniment.

From Oxford University Press USA:

How birds work to sing together

December 18, 2017

A new paper published in Behavioral Ecology finds that songbirds may coordinate both vocally and visually to enhance their singing partners’ responses.

In many group-living animals pairs sing together to defend resources, but such signals can be much more complex than that of the acoustic stimulus on its own. In addition to songs, cooperating animals may produce movements that can be precisely combined between partners and with songs. Experiments with robot birds revealed that coordination of vocal and visual components of the Australian magpie-lark audio-visual display enhances the receiver’s responses to this complex signal. Singing animals don’t just sing together; they also dance.

Animals communicate with their whole bodies. In humans, for example, vocal expressions are naturally produced with associated movements of the face, which reduces speech ambiguity. Because voices and lip movements are physically linked, even small modifications have a deteriorating effect on reception of the message, so coordination is a challenge in that it requires continuous monitoring of the partner’s behaviour.

Previous research showed that precise vocal coordination between cooperating animals increases the quality of their display; little is known, however, about the role of coordination between songs and movements. Partners of the rufous-naped wren, Campylorhynchus rufinucha, for example, combine multiple types of songs and body movements in a coordinated fashion. Researchers have suggested that movements such as these may improve vocal coordination within a pair. The movements’ diversity and precise match with the songs suggest that both components signal jointly to other pairs.

This paper used robotics to analyze the coordination in the duets of the Australian magpie-lark Grallina cyanoleuca. Researcher here used a pair of magpie-lark robotic models. The models used taxidermic skins, so the color, pattern, and surface texture were realistic. The tests combined vocal duet playback with robotic models that produced wing movements and tested whether audio-visual coordination enhances the receiver’s responses during interactions in this species.

The researcher working on this study performed three experiments with two treatments each to test how magpie-larks respond to duets coordinated acoustically and visually between animals and audio-visually within an animal. The reaction was measured by the number of songs and flying toward the robots by the male and female.

Each experiment involved the same twelve pairs of birds, with at least four days between consecutive experiments with a pair. The experiments consisted of two treatments carried out on the same day with a pair. Such a scheme aimed at maximum precision of animal comparisons. The order of treatments and experiments was balanced by design with respect to the pair and sex of the duet initiator. Each treatment lasted 10 minutes.

The results indicated that magpie-larks responded differently to coordinated and uncoordinated duets. Both males and females initiated more songs in response to fully coordinated treatments than to treatments that were uncoordinated, suggesting that full coordination created the strongest signal. Overall, females initiated fewer songs than males. Similarly to song initiations, pairs produced more duets and were more likely to fly toward the model birds in response to coordinated treatments than to all uncoordinated treatments. Playbacks that were precisely coordinated in terms of either movements or songs without coordination in the other channel did not increase the perceived territorial threat of the display relative to playbacks that were uncoordinated in both channels between animals but coordinated between channels within an animal.

“Multimodality of signals can be beneficial for the signaller as well as for the receiver because there are many ways through which one signal component can improve the efficacy of the other, said the paper’s author, Pawe? R?k. “The problem appears when signal components are not aligned in time because the mismatch creates illusions and conflicts from the perspective of the receiver. Multimodal coordination within individuals has been studied for many years but it concerned signals with mechanistically constrained components. This study shows that it is also important in cooperatively signalling species, in which coordination is not an effect of a physical constraint but motivation and experience of partners.”

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Bearded dragon in Australia


This video says about itself:

13 December 2017

On this episode of Breaking Trail, Coyote finally catches one lizard he has always been after, the Bearded Dragon! One of Australia’s most iconic lizard species the Bearded Dragon is world-famous for its incredibly spiky appearance and popularity in the world of herpetology.

Australian beetles’ colours, new study


This video from Australia says about itself:

25 February 2017

A slideshow of leaf beetles in the genus Paropsisterna.

From the Yale-NUS College in Singapore:

Beetles’ bright colors used for camouflage instead of warning off predators

First study to examine beetle colouration in their natural habitat prompts discovery

December 4, 2017

NUS College Postdoctoral Fellow Eunice Tan has discovered that the bright colour patterns of beetles are not a warning signal to predators as previously believed, but actually a form of camouflage, turning an old assumption on its head. Dr Tan, along with four collaborators from Australia and Spain, examined 51 species of Australian leaf beetles in their natural habitats, and discovered that each beetle’s colour pattern is similar to the host plants that the beetle lives on, suggesting that those conspicuous colours help the beetle blend in with the plants it inhabits. The study was recently published as an open-access article in the peer-reviewed journal Frontiers in Ecology and Evolution.

As the first ecologist to examine the colour patterns of live leaf beetles in relation to their host plants, Dr Tan contextualised the colour patterns of beetles to their natural habitats, which allowed her to challenge the prevailing theory among coleopterists — scientists who study beetles — that the bright colours of leaf beetles developed as a deterrent signal to predators. These colourful markings were assumed to be a warning to predators against eating the beetles, which are able to secrete poisonous chemicals in self-defence. However, this idea was based on earlier studies, which focused on using museum collections of beetle specimens for their analyses. While this method affords researchers a large number of samples, the discolouration of deceased specimens made accurate colour analysis of the beetles impossible. Furthermore, such methodology also fails to take into account the colouration of each beetle’s natural environment.

Dr Tan and her team spent 17 months photographing live beetles in 32 locations across four Australian states, in order to compare each beetle’s colouration to the colour of the leaf it was found on. Taking into account the evolutionary relationship between the different beetle species, Dr Tan discovered that different species of beetles had colour patterns similar to those of their host plants. This suggests that the colourations have a camouflaging effect, rather than serving an aposematic (predator-deterring) function. This camouflage effect was particularly pronounced in beetles which fed on multiple types of plants, as they had to blend into many different environments.

“It was long thought that conspicuous colour patterns served to advertise the distastefulness of an organism to its predators. However, we have found that this cannot be the sole reason that conspicuous colour patterns developed in leaf beetles. In general, the beetles had colouration similar to that of their host plants, suggesting that there is natural selection at play and therefore some evolutionary advantage for these beetles to use camouflage as a defensive strategy against predators,” shared Dr Tan.

Through her field studies, Dr Tan also observed the impact of ecological factors on the evolution of different beetle species’ colouration patterns. Dr Tan’s study found that both larger and smaller beetle species in her sample had similar levels of colour contrast against their backgrounds. However, the larger beetle species were more likely to be found in darker environments than their smaller cousins, suggesting that they were employing a hiding strategy against predators, despite having similar conspicuous colouration to their smaller cousins. An ecological property, the brightness of the environment, was therefore a potential factor influencing the evolution of beetle colouration.

Taken together, the findings of this study “point to a complex suite of factors driving natural selection, such as types of predators and host plant choice, which affect the evolution of colouration in leaf beetles,” said Dr Tan. Challenging the assumption that the sole explanation for bright coloration in leaf beetles is meant to ward off predators, Dr Tan postulated that the variety of anti-predator strategies in leaf beetles that she has found may explain their successful spread into a variety of habitats.

Great Barrier Reef fish protection works


This 2015 video is called Australia’s Great Barrier Reef || Full Documentary with subtitles.

From PLOS ONE:

Great Barrier Reef protected zones help fish in even lightly exploited areas

Fish biomass up to five times greater compared to unprotected zones at northernmost reefs

November 8, 2017

Protected zones of the Great Barrier Reef benefit fish even at the relatively lightly-fished northern reefs, according to a study published November 8, 2017 in the open-access journal PLOS ONE by Carolina Castro-Sanguino from the University of Queensland, Australia, and colleagues.

The Australian Great Barrier Reef Marine Park is the largest network of marine reserves in the world, and includes both ‘no fishing’ (‘no-take’) and ‘no-entry’ zones as well as fished areas. The authors of the present study analyzed the effect of such policies in the relatively lightly-fished northernmost regions. They measured, counted and calculated the biomass of commonly-fished species found at 31 northern, central and southern reefs in the area north of Cooktown, as well as assessing the seabed habitat at these sites.

The authors found that fish biomass was up to five times greater in protected zones which prevented fishing, whether they had ‘no-take’ or ‘no-entry’ policies. The most remote northern reefs had greater fish biomass than more southern zones, regardless of the zones’ policies, and the authors speculate that poaching may be common in southern reserves. They also found indication that fishers may frequently operate at reserves’ boundaries to exploit the increased fish biomass in these reserves.

The specific seabed habitat of different reefs had a strong effect on the amounts and types of fish found, making it impossible for the researchers to discern any distinct effects of ‘no-take’ versus ‘no-entry’ policies. Nonetheless, they did find clear differences in biomass between protected and unprotected areas, despite this region being generally fished relatively lightly. They state that this illustrates the high sensitivity to fishing of many species, reinforcing the case for their protection.

“Even in remote reef habitats, marine reserves increase the biomass of exploited fish but detecting these benefits can be challenging because the state of corals also varies across some management zones and these patterns also affect fishes,” says Castro-Sanguino. “We also conclude that fishing is most intense near reserve borders leading to a reduction of biomass just outside reserves.”

Deep-sea fish eyes, new research


This video from Australia says about itself:

New twilight eye cells discovered in fish

7 November 2017

A new type of cell has been found in the eye of a deep-sea fish, and scientists say the discovery opens a new world of understanding vision in a variety of light conditions.

QBI scientists found the new cell type in the deep-sea pearlside fish (Maurolicus spp.), which have an unusual visual system adapted for twilight conditions.

From the University of Queensland in Australia:

Deep-sea fish reveals twilight trick

A new type of cell has been found in the eye of a deep-sea fish

November 8, 2017

Summary: A new type of cell has been found in the eye of a deep-sea fish, and scientists say the discovery opens a new world of understanding about vision in a variety of light conditions. Scientists found the new cell type in the deep-sea pearlside fish (Maurolicus spp.), which have an unusual visual system adapted for twilight conditions.

A new type of cell has been found in the eye of a deep-sea fish, and scientists say the discovery opens a new world of understanding about vision in a variety of light conditions.

University of Queensland scientists found the new cell type in the deep-sea pearlside fish (Maurolicus spp.), which have an unusual visual system adapted for twilight conditions.

Dr Fanny de Busserolles at UQ’s Queensland Brain Institute said the retina of most vertebrate animals — including humans — contained two photoreceptor types: rods for vision in dim light, and cones for daytime vision. Each had different light-sensitive proteins.

“Deep-sea fish, which live at ocean depths below 200m, are generally only active in the dark, so most species have lost all their cones in favour of light-sensitive rods,” Dr de Busserolles said.

Pearlsides differed in that they were mostly active at dusk and dawn, close to the water’s surface where light levels are intermediate.

“Previously it was thought that pearlsides had retinas composed entirely of rods, but our new study has found this isn’t the case,” Dr de Busserolles said.

“Humans use their cones during the day our [sic; or] rods at night, but during twilight, although not ideal, we use a combination of both.

“Pearlsides, being active mainly during twilight, have developed a completely different solution.

“Instead of using a combination of rods and cones, they combine aspects of both cells into a single and more efficient photoreceptor type.”

The researchers found that the cells — which they have termed “rod-like cones” for their shapes under the microscope — were tuned perfectly to the pearlsides’ specific light conditions.

Research leader Professor Justin Marshall said the study was significant.

“It improves understanding of how different animals see the world and how vision might have helped them to conquer even the most extreme environments, including the deep sea,” Professor Marshall said.

“Humans love to classify everything into being either black or white.

“However our study shows the truth might be very different from previous theories.

“More comprehensive studies, and caution, are needed when categorising photoreceptor cells into cones and rods.”

The study is published in Science Advances.

Saving Australia’s endangered mountain pygmy possums


This 2015 video is called Mountain Pygmy Possums – Endangered Species Edit.

From the University of Melbourne in Australia:

Genetic rescue boosts recovery of Australia’s endangered mountain pygmy possums

October 23, 2017

For the first time, a breeding technique known as genetic rescue has been shown to increase population numbers and survival rates of the endangered mountain pygmy possum, now at their highest numbers since 1996.

The study was conducted by a team from the University of Melbourne, La Trobe University, CESAR, Mt Buller Mt Stirling Resort Management, and the University of New South Wales.

Dr Andrew Weeks from the University of Melbourne led the project, published in the international journal Nature Communications.

Genetic rescue was used to introduce male mountain pygmy possums, Burramys parvus, from a healthy population at Mt Hotham, to a recipient group of females at Mt Buller. The two groups had become physically isolated from each other over 20,000 years.

This isolation had led to inbreeding and a lack of the genetic variation that is essential for overcoming disease and ensuring the ability to thrive.

Dr Weeks says that since the genetic rescue program began in 2011, the possum population has gone through rapid growth and is now larger than when the population was first discovered in 1996.

“Before 2010, there was thought to be only a handful of individuals at Mt Buller,” Dr Weeks says. “Now, Mt Buller females from the genetic rescue are bigger and have more offspring that survive longer than the progeny of pygmy possums born outside the program. We now estimate the population to be over 200 possums,” he says.

Co-author Dr Ian Mansergh from La Trobe University says the study’s findings mark an important development in conservation management.

“Our study confirms genetic rescue as a successful conservation technique, especially when used for small, isolated populations of threatened species,” Dr Mansergh says.

Along with genetic rescue, there was also a program of habitat restoration, predator control and environmental protection instituted by the land manager, Mt Buller Mt Stirling Resort Management.

The researchers say this was essential to avoid losing the benefits of genetic rescue if populations cannot expand and still face the threats that reduced the population in the first place.

Dr Weeks and the University of Melbourne’s Professor Ary Hoffmann, who co-authored the possum paper, are now also leading a genetic rescue program for the critically endangered Eastern Barred Bandicoot at Mt Rothwell Conservation Centre near Little River in Victoria.

Prof Hoffmann says the long-term hope for genetic rescue is that it will provide endangered animals with enough genetic variation to adapt and evolve to new challenges, such as climate change.

“These animals are now facing an extra threat. They are experiencing physical isolation and introduced predators as well as climate warming,” Professor Hoffman says. “The hope is that animals can adapt if we give them the genetic tools to do so.

“We have shown the technique is successful in the mountain pygmy possum, and hope the Eastern Barred Bandicoot can recover if they are also given enough support.”

What albatrosses eat


This video says about itself:

Wings of the Albatross | National Geographic

8 August 2011

Photographer Frans Lanting talks of his epic journey to capture images of the albatross, a hauntingly beautiful bird enshrined in legend and poetry.

From ScienceDaily:

Albatross feces show diet of fishery discards

New, non-intrusive way to assess seabird diet could help improve fisheries management and monitor marine biodiversity

October 4, 2017

Summary: The first-ever analysis of fish DNA in albatross scat indicates a high level of interaction between seabirds and commercial fisheries. This non-invasive method could be used to assess whether fisheries are complying with discard policies. Extending the analysis to other marine predators could help monitor marine biodiversity and broader marine ecosystem changes.

Albatross feed on several fish species that are not easy for the birds to access in nature, but which are caught by commercial fisheries, finds a study in open-access journal Frontiers in Marine Science. This indicates a high level of interaction between albatross and fisheries in some areas, and so an ongoing risk of the birds being killed in fishing gear.

The study is the first broad geographic assessment of seabird diet through DNA analysis of feces — and the first to examine the diet of any Southern Ocean species in this way. This non-invasive technique could serve as a valuable tool for fishery and conservation management into the future.

Albatross are threatened by commercial fisheries

Commercial fishing practices are still the biggest direct threat to most albatross species, although many advances have been made in some fisheries. The birds are attracted to bait used on longline hooks, as well as to non-target fish and processing waste that is discarded from fishing boats. However, by scavenging behind vessels, many get tangled in the fishing gear and drown. This incidental mortality, or bycatch, kills hundreds of thousands of albatross and other seabirds each year. Fishers, conservationists and managers globally are working to find solutions.

“A better understanding of seabird-fishery interactions would help improve ecosystem-based management of fisheries,” says Julie McInnes from the Institute for Marine and Antarctic Studies at the University of Tasmania, Australia. “However, it can be difficult to assess what proportion of a seabird population may interact with fishing vessels and whether this interaction is similar across different breeding colonies and fishing zones.”

Seabird diet can reveal interactions with fisheries

One way to assess how seabirds are interacting with fisheries is to look at what the birds are eating. Conventional techniques involve directly analyzing stomach contents for the presence of different prey species. However, sample collection can be invasive and body parts from different species are not always distinguishable after digestion.

McInnes and an international team took a different approach: instead of stomach contents, they analyzed the DNA in albatross feces.

“Detecting prey DNA in predator scats provides a non-invasive tool to examine diet,” says McInnes. “We wanted to test whether this “DNA barcoding” is a valuable method for assessing seabird-fishery interactions.”

High level of fishery interactions in some areas

The researchers collected droppings from black-browed albatross at six breeding sites across their circumpolar range over two years, including colonies that had rarely or never been studied in the past.

DNA analysis of the feces showed that the birds consume a wide diversity of fish species, and identified a number of new prey species. Moreover, many of the identified fish species are not known to be naturally available to albatrosses, but are commercially harvested or caught as bycatch. The areas with the highest proportion of these species were sites where discards are still permitted by the fishery.

“These species were likely obtained by scavenging on discards from fisheries operating adjacent to the colony,” says McInnes. “This indicates ongoing interactions of black-browed albatross with fisheries.”

New, valuable tool for fishery and conservation management

Improvements to discard management are likely to have major implications for some albatross populations, she says. “By identifying the areas where seabird-fishery interactions are high, fishery resource managers can look at mechanisms to reduce the attractiveness of fishing vessels to albatross, and so reduce their mortality in fishing gear.”

The study demonstrates that DNA analysis of scat samples provides a valuable tool for fishery resource and conservation management. For example, long-term monitoring of albatross diet could be used to assess whether fisheries are complying with discard policies. Extending the analysis to other marine predators could help monitor marine biodiversity and broader marine ecosystem changes.

“DNA barcoding could be used to identify changes in the abundance and distribution of different marine species, for example in response to warmer oceans and climate change” says McInnes. “Understanding how these changes affect seabirds and other predators will be important for monitoring which populations are impacted.”

The research was led by the Institute for Marine and Antarctic Studies (University of Tasmania), the Australian Antarctic Division and the Tasmanian Department of Primary Industries, Parks Water and Environment.