population declines

How To Save Big Cats | Earth Wise

March 1, 2023 By EarthWise 1 Comment

Big cats are among the most widely recognized and admired animals in the world. But these charismatic predators face many and varied threats, including the loss of habitat and prey, conflicts with humans, poaching, and the illegal wildlife trade.

Researchers from the University of Reading in the U.K. have studied the fortunes of 50 species of large carnivores worldwide over the past 50 years. They found that social and economic factors, such as quality of life, were more closely associated with declines of large carnivore species than purely environmental factors, like habitat loss.

The study, which was recently published in the journal Nature Communications, suggests that the best way to save large carnivores, including lynx, bears, and lions, is to encourage a sustainable model of social and economic development instead of focusing exclusively on issues like climate change.

While rapid economic development pushes species to the brink of extinction, it’s also delivered enormous improvements in the quality of human life. But the analysis suggests that once people achieve a high quality of life and economic development slows, a turning point is reached and persecuted species have a chance to recover.

According to the research team, the recovery is a result of both improved habitat protections in advanced economies and a more harmonious relationship between people and predators. What would have once been considered a dangerous pest is now recognized as being an important part of both the ecosystem and culture.

In Western Europe, slower economic development and an improved quality of life have allowed populations of grey wolves to increase 1,800% since the 1960s.

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Economics trump environment to save big cats, say ecologists

Photo, posted February 8, 2015, courtesy of Mathias Appel via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

North American Birds And Climate Change | Earth Wise

August 10, 2022 By EarthWise Leave a Comment

Most plants and animals live in areas with specific climate conditions, such as rainfall patterns and temperature, that enable them to thrive. Any change in the climate of an area can affect the plants and animals living there, which in turn can impact the composition of the entire ecosystem.

As such, the changing climate poses many challenges to plants and animals. For example, appropriate climatic conditions for many species are changing. As a result, some may even disappear altogether. These problems can be compounded when the climate is changing in tandem with other human-caused stressors, such as land use change.

When there is increasing divergence between suitable climatic conditions for a particular species and its abundance and distribution through time, this is known as climate decoupling.

According to a new study recently published in the journal Nature Ecology & Evolution, some species of North American birds have not fully adjusted their distributions in response to climate change. The areas where these birds live have become more decoupled from their optimal climate conditions. Climate decoupling as a result of ongoing climate change could lead to additional stressors on many bird species and exacerbate bird population declines.

In the study, the research team analyzed data on bird population changes through time from the North American Bird Survey. They found that at least 30 out of 114 species (or 26%) of North American birds have become less well adjusted to their climate over the last 30 years. This means that their distributions and abundances were increasingly decoupled from climate over time.

The researchers also found that the overall trend of climate decoupling shows no signs of slowing down.

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North American birds not fully adjusting to changing climate

Photo, posted July 16, 2016, courtesy of Kelly Azar via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Even The Common House Sparrow Is Declining | Earth Wise

March 17, 2021 By EarthWise Leave a Comment

According to the first-ever comprehensive assessment of net bird populations published in 2019, nearly three billion birds have disappeared in the United States and Canada since 1970. The study, by researchers from the Cornell University Lab of Ornithology, found that North American bird populations have lost 2.9 billion breeding adults during that timespan. Forests lost one billion birds, and grassland birds declined 53%.

According to a newer study from Cornell University, it appears that even the common house sparrow is declining. In parts of its native range in Europe, house sparrow numbers are down nearly 60%. Researchers from the Cornell Lab of Ornithology sought to clarify the status of the species in the U.S. and Canada by using 21 years of citizen science data collected through its Project Feederwatch program.

Project FeederWatch is a winter-long survey of birds that visit feeders at backyards, nature centers, community areas, and other locales. For the study, which was recently published in the Wilson Journal of Ornithology, the research team reviewed recorded observations of house sparrows during their non-breeding season. These sightings from nearly 12,500 sites were used and cross-referenced with the National Land Cover database to determine whether the U.S. sightings came from rural or urban locations.

From 1995 to 2016, researchers found that Feederwatch sites reporting house sparrows declined 7.5%, and the mean flock sizes declined 22%. House sparrow populations declined in urban areas, but actually remained stable in rural areas.

The researchers say a lack of green space and nesting sites in urban areas are likely factors in the population declines.

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Study finds even the common house sparrow is declining

Nearly 3 Billion Birds Gone

Photo, posted May 14, 2014, courtesy of Jacob Spinks via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.