Wildlife & Biodiversity

Free-ranging domestic cats threat to conservation, eat 2,084 species globally & pushing some to extinction: Study

Almost half of the species were birds, followed by reptiles and mammals  

 
By Madhumita Paul
Published: Thursday 14 December 2023
Photo: iStock

Free-ranging domestic cats are a conservation threat, according to a new study led by researchers from Auburn University in the United States.

These feline species are also one of the most invasive species in the world, causing widespread diseases and driving some of their prey species to the brink of extinction, the study published in the journal Nature December 12, 2023 showed.

Islands contain three times more species of conservation concern eaten by cats than continents do, the authors of the study noted.

They identified 2,084 species consumed by cats, 347 (16.65 per cent) of which are near-threatened or of higher concern on the International Union for Conservation of Nature (IUCN) Red List.

According to the study, almost half of the species were birds, followed by reptiles and mammals. 

Cats were found to consume 981 species of birds, 463 of reptiles, 431 of mammals, 110 of insects and 57 of amphibians, the study noted.

According to the researchers, there has been no previous global attempt to comprehensively document the complement of species consumed by cats.

The researchers quantified the diet of free-ranging domestic cats throughout the world by taxonomic groups, island versus continental location, conservation status, body masses of diet species and the approach used to document the dietary items.

The study was based on over 150 years of literature documenting the negative impacts of free-ranging cats on the environment.

In this study, the researchers analysed 533 unique publications with records of species consumed by cats.

The researchers used a method called ‘observed predation’ to learn what free-ranging cats prey upon using the application of camera traps and animal-borne video.

The study found most studies of their prey have been conducted in Australia and its nearby islands and North America, and Africa, parts of Eurasia and South America all being underrepresented.

The researchers found records of cats consuming 11 species from Australia, Mexico, the United States of America and New Zealand that have since been listed as extinct in the wild or extinct. Many of these were island endemics such as the Hawaiian crow. 

The study also noted that 155 species or 7.44 per cent of the total number of species in the cat dietary compilation have not yet been evaluated under IUCN and most of these species were insects. 

The proportion of ‘Not Evaluated’ prey species was relatively high for Africa (17.54 per cent) and Asia (10.64 per cent).

The median adult body mass of vertebrate species reported in cat diet was 45.45g for all species, 13.67g for amphibians, 62.42g for birds, 53.22g for mammals and 21.35g for reptiles.

The study emphasised the need for conservation efforts, management and policy work. 

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