18種鳥類 13種哺乳類 保護等級只升不降
It’s not just bees, the world is losing its pollinating birds and mammals, new research shows. More pollinating bird and mammal species are moving towards extinction than away from it, finds the first global assessment of trends in pollinators.
About 90 percent of flowering plants are pollinated by animals and birds, and humans rely on many of these plant species for food, livestock forage, medicine and materials.
Nine percent of all known bird and mammal species are pollinators. Among mammals, bats perform this work, pollinating a large number of economically and ecologically important plants such as agave and cacti.
Key pollinating birds include hummingbirds, honeyeaters, sunbirds and white-eyes.
Lead author Eugenie Regan of the World Conservation Monitoring Centre said the research results are alarming. “It shows a worrying trend that may be impacting negatively on global pollination services, estimated to be worth more than US$215 billion.”
The assessment shows that on average, 2.4 bird and mammal pollinator species a year have moved one category towards extinction in recent decades, a “substantial increase in extinction risk” across this set of species, the IUCN said in a statement releasing the study today.
Habitat loss from unsustainable agriculture was found to be the main cause of decline for many species among both mammals and birds.
Pollinating mammals, such as the large-bodied fruit bats, are hunted for bushmeat, while birds are affected by invasive alien species.
During the period 1988 to 2012, 18 pollinator bird species qualified for being ‘up-listed’ to a higher threat category.
For example, the Regent Honeyeater, Xanthomyza phrygia, was up-listed from Endangered to Critically Endangered due to rapid population decline driven by drought, habitat loss caused by historic clearance for agriculture, and possibly competition with other species.
No pollinating bird species qualified for ‘down-listing’ to lower categories of threat.
Between 1996 and 2008, 13 mammal species identified as pollinators were up-listed to a higher threat category and two species qualified for down-listing to a lower category of threat.
For example, the Choco Broad-nosed Bat, Platyrrhinus chocoensis, moved from Vulnerable to Endangered due to habitat conversion to agriculture for cocoa, while among non-flying mammals the Sunda Slow Loris, Nycticebus coucang, moved from Near Threatened to Vulnerable due to harvesting for the pet trade and habitat loss.
On the other hand, the Pemba Flying Fox, Pteropus voeltzkowi, was down-listed from Critically Endangered to Vulnerable thanks to community conservation programs which provide protection at specific roost sites.
To determine the trend in the global status of pollinating birds and mammals, the authors used the Red List Index, an established method that shows trends in survival probability over time for sets of species using data from the IUCN Red List.
The Index is based on the proportion of species that move through the IUCN Red List categories over time, either away from or towards extinction.
The authors advise that this approach now needs to be expanded to include bees, wasps and butterflies.