Photo: Xu Zhongxi; Interview/Writer/Editor: Chen Qingzhong Environmental Information Center
In the evening, before the grass owl is about to start its activities, follow Lin Shizhong, chairman of the Kaohsiung City Wild Bird Society, to walk on the edge of the grass habitat where the grass owl used to breed, and from various clues, to determine whether there are still grass owl using and roosting. Lin Shizhong, chairman of the Kaohsiung Wild Bird Society, said that the remote hilly mountainous areas of Tainan and Kaohsiung are the most suitable environment for grass owl to inhabit because of their sparse population and relatively little interference with grass owl.
Taiwan's grass owl belongs to the endemic subspecies of the oriental grass owl, mainly distributed in the grassy land of the southern hilly area, because the face looks like a monkey from a distance, often called the monkey-faced eagle, is the only ground-dwelling owl in Taiwan. The grass owl feeds on small mammals, especially rodents, and is a breeding season from December to April of the following year, usually after dark, returning to its habitat to rest before dawn, and is a typical nocturnal bird.
Lin Shizhong, chairman of the Kaohsiung Wild Bird Society, walked on the edge of the grassy habitat where grass owl had been used for breeding, and judged from clues whether there were still grass owl using and roosting.
Because the grass owl is very difficult to detect, its ecological behavior is still unclear, and most of the previous sightings have been individuals who have mistakenly hit the bird's net, and they are becoming less and less seen. In 2008 the grass owl was listed as a First Class Endangered Conservation Species. Xia Rongsheng, head of the conservation team of the Forestry Bureau of the Agricultural Committee, said that according to the previous small regional survey model, the current number of grass owl in Taiwan is about 300 to 500, but it must be investigated more deeply.
The Taiwan grass owl belongs to the endemic subspecies of the oriental grass owl, and when it looks like a monkey from a distance, its face looks like a monkey, and it is often called a monkey-faced eagle. Courtesy of: Kaohsiung City Wild Bird Society.
Before we know the Grass Owl, many accidents have begun to happen one after another. In 2016, the Kaohsiung City Wild Bird Society observed three grass owl nest areas in the mountainous area, but the mother bird of one of the nests was found dead in front of the nest, and the four chicks in the nest have disappeared. The Kaohsiung bird will send the dead grass owl mother bird for testing, and found that there are three rodenticide components in the body, of which the exterminable rat has 0.34 ppm and the extinguished rat has 0.1 ppm, both of which have exceeded the lethal concentration of birds of prey.
The Kaohsiung bird will send the dead grass owl for testing and find that there is a rodenticide component in the body. Photo courtesy of: Kaohsiung City Wild Bird Society.
Although the Committee of Agriculture stopped the National Rat Eradication Week in 2015, which has been in operation for more than 30 years, it is still not difficult to find rat repellent scattered on the agricultural land in the southern countryside. Because the general public still has the habit of spraying drugs to kill rats after harvesting crops in late autumn, local agricultural and environmental protection units will still cooperate in distribution, and the ingredient that kills the mother bird of grass owl this time can kill rats, which may be environmental medicines from environmental protection departments.
On the rural farmland, it is still not difficult to find that the edge of the field is scattered with rat repellent.
Taiwan's rodenticides are mostly anticoagulants, and the blood of rats that eat the bait is not easy to coagulate, and will lose blood and die within a week, but the poisoned rats move slowly and are easily preyed upon by predators first, resulting in secondary poisoning. Lin Shizhong, chairman of the Kaohsiung Wild Bird Society, said that during the brooding period, grass owl can catch six to 12 mice a night, and even eat nearly 1,000 rats a year, so as a result of the vicious cycle of food chain, grass owl are often dead in the wilderness.
To reduce rat infestation, do you have to use rodenticide to be effective? The Wildlife Conservation Institute of Pingtung University of Science and Technology tried to start working with pineapple growers to set up nest boxes in the trees near the pineapple fields, hoping to attract the natural enemy of rats, the leading owls, to help control the rat infestation.
The Wildlife Conservation Research Institute of Pingke University and pineapple fruit farmers have set up nest boxes in the hope of attracting rats' natural enemies, the collared owl, to help control the rat infestation.
Cai Zhiwei, a graduate student at the Institute of Wild Protection of Pingke University, said that rat poison has obvious rat extermination effect in a short period of time, but if it does not continue to administer drugs, it will be due to breeding or the migration of rat populations in other regions to make up for it, so that the overall population will quickly recover. If the rats are controlled by birds of prey, the number of rats can be suppressed permanently and extensively.
In addition to introducing natural enemies to reduce rat infestation, the Pingke Ohno Pao Institute suggested that instead of applying drugs comprehensively at the same time, instead of regularly dispensing drugs at fixed points and recovering the corpses of poisoned rats, and switching to rat traps, etc., can achieve anti-rat infestation and reduce the accident of secondary poisoning.
Bird nets have also threatened the survival of grass owl for many years. In February 2017, a Kaohsiung bird would see a photo of a grass owl entangled in a bird rope and falling off a rice field on the Internet, and although the location of the incident was found the next day, it was too late to save the grass owl that had been in the net for a week. This netted male grass owl is still a sub-adult bird, weighing only 260 grams, almost half the weight of the average male bird, and it is believed that the wings are wrapped around the bird rope, unable to fly and starving to death. If the farmer who found the grass owl at that time could notify the conservation unit at the first time, the grass owl would still have a chance to be saved.
Bird nets have also threatened the survival of grass owl for many years. Photography: Xu Zhongxi.
The endangered grass owl is just one example, with the construction of roads, the pace of development to the low-altitude mountainous areas, such as the stone tiger, pangolin and many other precious and endangered species, but also because of the fragmentation of habitat and face an existential crisis. How to operate shallow hilly areas to avoid serious disturbances is an ecological proposition that must be faced squarely today.