202102/01
A major breakthrough has been made in the research of a mysterious protected species—the Eastern grass owl. The Pingtung Forest District Office of the Forestry Bureau, Council of Agriculture, and the Bird Ecology Lab, National Pingtung University of Science and Technology (NPUST Bird Ecology Lab) have collaborated to set up over 20 artificial perches specially designed for grass owls around the Kaohsiung-Pingtung region. The locations where perches were set up include farmlands, grasslands, and riverbanks, environments where grass owls are likely to be found. Results show that nearly half of the perches have recorded rare grass owl sightings, confirming that raptor perches can be an effective way to investigate the behaviors of grass owls. Researchers have also learned that grass owls are using raptor perches as a higher vantage point to observe and catch rodents in farm fields, helping farmers who use environmentally-friendly farming methods reduce crop losses and creating a positive ecological cycle in which humans and wildlife can coexist and thrive together.
Grass owls are adapted for life on the ground, unlike most other owls that live on trees, making it a unique species in Taiwan. They can be mainly found in undeveloped grasslands across the plains and foothills in the south-central region of Taiwan. Grass owls rest and nest on the grass during the day. As its heart-shaped face resembles the profile of a cut apple, it was often called the "flying apple”; it was also known as the monkey-faced owl in the early days. The Eastern grass owl is a sub-species endemic to Taiwan and a Level I protected species. Due to its scarcity and the difficulty in sighting their whereabouts, there is a lack of ecological data on the grass owl. The loss of their habitat and the danger posed by the use of rodenticides represent the biggest threats to their survival, making them the only endangered owl species in Taiwan. In 2018, when the Executive Yuan approved the Forestry Bureau's plan to launch the Taiwan Ecological Network Project, the grass owl was selected as one of the key indicator species for the southern Taiwan ecology green network.
However, because of its nocturnal nature and scarcity, the biggest obstacle for its research was trying to locate these owls. Previous studies attempted to attract grass owls by broadcasting their calls, but the success rate was very low. Raptor perches are an ecological control strategy used by farmers in Europe, America, and Australia. In the past, NPUST Bird Ecology Lab used raptor perches with great success to "invite black-winged kites to catch rats”, in order to reduce the ecological hazards of rodenticides. At the same time, automatic cameras on the perches recorded many raptors and insectivorous birds using these perches, which demonstrated that perches can help farmers catch rats and insects and assist investigators researching the populations of local birds.
In recent years, the Forestry Bureau has been vigorously promoting environmentally-friendly agriculture; farmers who care about the land and ecosystem have joined in by taking actions that include stopping the use of chemical pesticides and rodenticides to create a viable habitat for wildlife. However, the resulting rodent and pest infestations have become a problem for these farmers. In view of this, since April 2020, the Pingtung Forest District Office of the Forestry Bureau in collaboration with the NPUST Bird Ecology Lab have built low perches for the ground-nesting grass owl. These perches are set up in locations where grass owls are likely to be found to test whether they will use them. It is also hoped that grass owls can help farmers get rid of rodents in a more natural way.
This project, which involved setting up perches at 21 different locations around Kaohsiung and Pingtung, and monitoring them for at least three months, showed quite surprisingly positive results. In ten of these locations, grass owls stopped to rest. The first of these perches had an owl sighting captured on camera the same night after being set up, while the last perch took one month to sight an owl. Some of the perches were frequently used by grass owls. Not only were they used regularly, but some owls even stayed for more than an hour per night. On these perches, grass owls hunted, preened, and napped, there were even two owls that chased one another. These behaviors that were difficult to observe directly in the past were all captured by the automatic infrared camera system (black and white images). Throughout several months of monitoring, tens of thousands of photos and videos have been taken.
The results of this study not only helped break through the obstacles in the research of grass owls, but also confirmed that certain seemingly barren lands and riverbanks are important habitats for these owls. The agricultural land surrounding the grass owl's habitat is the ideal foraging and hunting environment for them at night. Since the grass owl mainly feeds on rodents, and can even catch "ghost rats" (greater bandicoot rat) effortlessly, the grass owl has a high potential to become a rodent control alternative. After it is proven that grass owls are willing to use the perches, they will join the ranks of black-winged kites and collared scops owls and become "free rodent hunters" for environmentally-friendly farmers, since perches can be set up to attract grass owls to roost and hunt rodents in the fields. According to Hong Shiao-Yu, a researcher at the NPUST Bird Ecology Lab who is in charge of implementing the project, 9 species of raptors and 23 species of non-raptor birds have been recorded using the perches. Different areas and environments have different bird species, so setting up perches in fields has brought many surprises; farmers who set up perches in their fields were also astonished to find out that there was such a rich ecosystem flourishing in their fields!
According to the Forestry Bureau, the "Payments for Ecosystem Services for Endangered Species and Critical Habitat Promotion Program" will be implemented starting in 2021. As long as the criteria of not using herbicides, rodenticides, and traps in the critical habitats of leopard cats, grass owls, otters, and pheasant-tailed jacanas are met, an incentive payment of up to NT$20,000 per hectare per year will be granted. This measure will allow farmlands to be a safe habitat for these endangered species, while environmentally-friendly farmers receive a reward for their mindful management of the land and for upholding important public welfare values on behalf of all people. This is equivalent to receiving a salary for protecting the ecosystem. The Forestry Bureau emphasizes that not using rodenticides protects grass owls and other raptors that can be great partners for farmers, helping them manage rodent infestations in their fields, feeding two birds with one scone. We hope that more farmers can join the ranks of eco-friendly production and move towards a sustainable "three-in-one" model of "production”, "lifestyle”, and "habitat”.