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The behaviour of cat interactions has been categorised into playful, aggressive and intermediate groups that may help owners distinguish between play and genuine fighting. The study, published in Scientific Reports, suggests that cats may engage in a mixture of playful and aggressive behaviours, which could escalate into a fight if not managed by the owner.

Noema Gajdoš Kmecová and colleagues evaluated 105 video clips sourced from YouTube and directly from cat owners of interactions between 210 cats. Based on initial observations of the cats, the authors assembled six observable behaviour categories including wrestling, chasing and vocalisation, which they then used to assess the remaining cats. Cats were grouped based on the frequency and duration of the six behaviours. Separately, four of the authors reviewed the same videos and came up with three groups to define the interactions between cats: ‘playful’ (friendly interactions); ‘agonistic’ (aggressive interactions); or a third category, ‘intermediate’ (a mixture of both playful and aggressive behaviour).

More than a half of the cats (56.2% or 118 cats) were described by the authors as playful in their interaction, 28.6% (60 cats) were labelled as agonistic, and 15.2% (32 cats) were labelled as intermediate.

When comparing the cat behaviour groups with the three interaction groupings defined by the authors, they found that wrestling behaviour between cats was most closely associated with the playful group, while vocalization and chasing were associated with the agonistic group. The intermediate group, while observed as having characteristics of both, was more closely related to the playful group than the agonistic group. The intermediate group showed prolonged exchanges of behaviours such as laying on their back with their belly upwards, pouncing, stalking, and approaching and grooming each other.

The authors suggest that this combination of playful and aggressive behaviours may reflect a short-term disagreement in social behaviour between the cats, rather than a break-down in the relationship. The authors suggest that identifying potential tension between cats may help owners manage the relationship to avoid escalation and the need for separation.
 

The oldest-known fossil of a worm-like amphibian known as a caecilian is reported in this week’s Nature. The finding sheds light on the origins of caecilians and their position in the amphibian group.

Modern-day caecilians are limbless amphibians that look like worms or snakes. Their origins are poorly understood, due to a paucity of relevant fossils. In this study, Ben Kligman and colleagues analysed the fragmented, fossilized remains of at least 76 individual caecilians, found in the Upper Triassic Chinle Formation of Petrified Forest National Park, Arizona, USA. Dated at 220 million years old, the findings extend the caecilian fossil record by 35 million years.

The creature combines features found in the common ancestor of living caecilians with those of an extinct group of four-legged amphibians called the dissorophoid temnospondyls. It is also missing certain features that are present in modern caecilians, such as the tenticular organ. As such, it bridges the gap between modern caecilians and extinct tetrapods and confirms the position of caecilians within Lissamphibia: the group that also contains frogs and salamanders.

Declines in the populations of the world’s largest carnivores — such as lions, tigers, and wolves — may be more strongly associated with human socioeconomic growth than habitat loss or climate change, suggests a modelling study published in Nature Communications. The findings highlight potential trade-offs between improving the living standards of people and maintaining carnivore populations, which could challenge the achievement of the UN Sustainable Development Goals (SDGs) to promote human development growth.

Previous research has improved our understanding of biodiversity and threats to wildlife populations. However, the drivers of biodiversity change at global scales and the role of human socioeconomic factors (such as improved income, education, and life expectancy) on wildlife populations — including large carnivorous mammals — remain less clear.

Thomas Johnson and colleagues analysed features that drive population declines, and recoveries of 50 species of the world’s largest carnivores — including lions, tigers, and wolves — in over 1,000 populations around the world. The authors found that the leading driver of biodiversity change is changes in human development, and not climate change or habitat loss, as previous studies suggested. They also ran simulations to project how such changes might have shaped carnivore abundances over the past 50 years. The authors found that when human development growth is fast, carnivore populations decline sharply. However, as human development growth slows and begins to plateau, carnivore populations show the capacity for population growth and recovery, potentially revealing strategies that could help address biodiversity loss.

The findings reveal conflicts that could hinder the achievement of the UN SDGs in developing countries, as improvements in health, education and income could negatively affect progress towards improving terrestrial ecosystems. The authors note that more work is needed to establish the mechanisms linking human development growth with carnivore declines.