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Extensive Data Collected Over 8 Years of Wildlife Monitoring Shows Great Abundance of Formosan Reeves’s Muntjac and the Expansion of Formosan Sambar Populations to Lower Altitudes

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202405/01
The Forestry and Nature Conservation Agency (FANCA), Ministry of Agriculture, has set up automatic cameras to conduct long-term wildlife monitoring in national forest areas, with over 480,000 photos of wildlife taken over the past eight years. In terms of the cumulative number of photos representing the relative abundance of each species, the top three species are the Formosan Reeves’s muntjac, Formosan macaque, and Formosan ferret-badger. The proportion of photos taken at the sampling points of the Formosan sambar, which is a member of the Cervidae family along with the Formosan Reeves’s muntjac, has also risen sharply over the past eight years from 1.63% to 30.66%. In addition, the home range of the Formosan sambar has expanded from the mid- and high-altitude areas in the past to the lower elevation areas that are close to the plains.

Since September 2015, the FANCA has installed infrared automatic cameras in national forest areas for wildlife monitoring. In recent years, the FANCA has enlisted the assistance of Prof. Weng Guo-Jing of National Pingtung University of Science and Technology (NPUST), Associate Prof. Liu Chien-Nan of National Chiayi University, and experts of the Academia Sinica, to expand the installation of additional cameras at different elevations. Currently, there are 387 sampling points carrying out long-term monitoring to observe the changes in the populations of medium- to large-sized wild mammals.

Sampling point setting and data downloading for this long-term wildlife monitoring system are all carried out by the forest rangers of the FANCA’s various branches. From basic camera setup and battery replacement to image data retrieval and animal identification, a standardized mode of operation has been adopted in order to minimize interference with wildlife. Only through years of collecting and analyzing data can the system achieve such substantial and concrete results.

According to the FANCA, from September 2015 to July 2023, more than 124 million hours of video have been recorded, with a total of 480,000 valid photos taken. As the number of photos taken of each species reflects their relative abundance, the top 10 most photographed species were the Formosan Reeves’s muntjac (287,957 photos), Formosan macaque (54,359 photos), Formosan ferret-badger (48,389 photos), squirrels (18,470 photos), Formosan masked palm civet (15,731 photos), Formosan crab-eating mongoose (12,334 photos), Formosan sambar (12,146 photos), Formosan serow (10,371 photos), Formosan wild boar (6,700 photos), and Formosan small Indian civet (6,264 photos). The FANCA further explained that there is an underestimation of the relative abundance of macaques and squirrels as the automatic cameras mainly captured animal activities on the ground level.

According to the FANCA, the relative abundance of wild animals and the long-term changes in trends are important references for conservation decision-making. For example, in 2019, when three mammal species—Formosan Reeves’s muntjac, Formosan macaque, and Formosan masked palm civet—were reclassified from the protected species category to the general wildlife category based on the current status of the wildlife resources assessment, there were concerns about the need to protect these species in the future due to possible over-hunting. The results of long-term monitoring showed that the occurrence index (OI) of the Formosan Reeves’s muntjac, which was 19.4 in 2019, had increased to 31.4 in 2022, while the OI of the Formosan macaque increased from 3.85 to 5.43, and that of the Formosan masked palm civet increased from 1.26 to 1.33, indicating that the populations of the three species are in good condition.

In addition, the OI of the Formosan sambar, which still falls under the protected species category, increased from 0.61 in 2015 to 1.79 in 2022, even though it is also among the traditionally hunted wildlife of Indigenous people. This shows that the abundance of this species is increasing year by year. Moreover, the number of camera points where photos of the Formosan sambar were taken also increased from 1.63% in 2015 to 30.66% in 2022. The FANCA pointed out that in the past, Formosan sambar were mostly found in the high-altitude areas of the Central Mountain Range, but they have been gradually expanding downwards in recent years. Moreover, the trend of increasing abundance is the most obvious in the range of 1,000 to 2,000 meters above sea level, showing that they are continuing to move into the low-altitude mountain areas. Captured by the monitoring cameras, the distribution record of the lowest elevation is 135 meters above sea level in the Shanlin District of Kaohsiung City.

In addition to enabling researchers to understand the distribution of species and population trends, automatic camera monitoring also provides information on animal lifecycles and behaviors. Using the Formosan sambar as an example, the FANCA has discovered that although it is active throughout the day, its activities peak between 04:00-06:00 AM. Every spring is the antler growing season for bucks, after the hairy skin (velvet) recedes, the antler growth progresses to the hard horn stage, which coincides with the breeding season for the Formosan sambar. Fawns are mostly seen in the summer, when the weather is at its hottest.

In addition, Formosan black bears have been photographed more frequently, with the OI for species abundance increasing year by year. Many times, cubs or mothers with young bears have been photographed, which not only indicates that the population distribution is spreading, but also shows that the species is reproducing well.

The FANCA also announced that from this year onward, automatic camera points will be significantly increased, so that long-term monitoring of wildlife can be expanded from national forest areas to include all of Taiwan’s low-elevation mountains and plains. This will help us keep abreast of the wildlife population trends across the country and formulate more specific wildlife management policies.

The FANCA reminds the public that any illegal behavior such as harassment, abuse, poaching, slaughter, or other exploitation of the species will be prosecuted and fined in accordance with Articles 41 and 42 of the Wildlife Conservation Act.
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