Australia’s native noisy miner bird is more of a pest than originally thought, with new research from La Trobe University showing it is preventing forest birds from persisting in residential suburbs. Photo credit: Geoffrey Moore via Unsplash
Research shows noisy miner birds are bullying forest birds from urban areas, writes Jacinta Humphrey, based at the Research Center for Future Landscapes, La Trobe University (Phys.Org December 8, 2023)
The team of researchers has found that forest birds face two distinct, yet interrelated challenges in urban areas: the loss of suitable habitat due to urban development, and the dominance of noisy miners which aggressively exclude small birds.
Jacinta, who is a Ph.D. student, says the conservation of biodiversity in urban environments is a global priority, given the expanding footprint of cities worldwide and the growing percentage of the human population living in such areas. But now, added to that, we have these aggressive birds colonising urban landscapes.
This is not a phenomenon isolated to Melbourne, where the research was conducted. It’s happening in the Newcastle / Lake Macquarie region as well.
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Free-ranging cats kill thousands of species — and some of them are endangered, study finds, by Matthew Rozsa, Salon, December 12, 2023
The diet of outdoor cats regularly includes at least 347 known species that are of conservation concern.
Free-ranging cats are “invasive carnivores” and among “the most problematic invasive species in the world,” according to a recent study published in the journal Nature. Defining “free-ranging cats” as “owned or unowned cats with access to the outdoor environment,” researchers from the United States, Australia, New Zealand and France reviewed 533 studies on free-range cat diets to learn more about their impact on local ecosystems. In the process, they discovered there are at least 2,084 species eaten by cats — of which 347 are of conservation concern. “Birds comprised 47.07% (981 species), followed by reptiles (463 species, 22.22%), mammals (431 species, 20.68%), insects (119 species, 5.71%), and amphibians (57 species, 2.74%),” the authors explain.
The scientists also noted the shocking range of cat diets, characterizing them as “extreme generalist predators” who will feed off of animals as large as American bullfrogs, emus, green sea turtles and domestic cows. “Approximately 9% of known birds, 6% of known mammals, and 4% of known reptile species are identified in cat diets,” the researchers add. While their omnivorous dietary skills are impressive, they also have a dire impact on native species. The scientists point out that the confirmed 2,084 species known to be eaten by cats is almost certainly quite low compared to the total number, given how many regions in the world (including Africa) have scant research on domestic cat diets. Yet their final conclusion is inescapable.
“Cats depredate and scavenge a large fraction of the species present across the range available in the landscapes they forage in,” the authors write. Experts urge cat owners to keep their animals indoors. In the United States alone, outdoor cats kill 2.4 billion birds every year and have contributed to the extinction of at least 63 species of birds, mammals, and reptiles.
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Cats prey driving many species to extinction
Free-ranging cats are “invasive carnivores“ and among “the most problematic invasive species in the world,” according to a recent study published in the journal Nature.
A global synthesis and assessment of free-ranging domestic cat diet, by Christopher A. Lepczyk, and colleagues, Nature journal, 12 December 2023
Introduction
Since house cats (Felis catus) were domesticated over 9000 years ago, humans have introduced them across much of the world1. Today, cats inhabit all continents, except Antarctica, and have been introduced to hundreds of islands2, making them amongst the most widely distributed species on the planet. Because of this cosmopolitan distribution, cats have disrupted many ecosystems to which they have been introduced3. Specifically, cats spread novel diseases to a range of species including humans4,5, out-compete native felids and other mesopredators6, threaten the genetic integrity of wild felids7, prey on native fauna8, and have driven many species to extinction9,10. As a result, free-ranging cats (i.e., owned or unowned cats with access to the outdoor environment11) are amongst the most problematic invasive species in the world12.
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DAILY SCIENCE
What’s on the menu? For cats, just about everything.
New research documents the vast and varied appetite domestic cats have for wildlife, including endangered species.
By Warren Cornwall, Anthropocene magazine, December 13, 2023
Pet food companies might benefit from the idea that cats are picky eaters, satisfied only by that special can of tuna-flavored food. But Chris Lepczyk knows better.
Over the last two decades, the Auburn University ecologist has amassed a tally of all the different creatures domesticated cats have been documented eating. The number has passed 2,000 species and shows no signs of slowing.
“It sure seems there’s not a lot that a cat would pass up,” says Lepczyk.
Despite all the cute cat videos, it’s been long known Felis catus is a fierce killer, particularly when it comes to birds and small mammals. By one estimate domestic cats kill as many as 4 billion birds and 22.3 billion mammals per year in the United States alone.
But Lepczyk wanted to know just how broad these animals’ palates are. The findings could have implications for scientists and policymakers trying to understand how cats are contributing to changes in ecosystems or affecting the fates of endangered species.
MMM Issue 43, April-May 2024
