Researchers have learned about the behavior of purple butterflies in the gorge over the past 34 years and have witnessed damage to the habitat as well. Maolin is a settlement of the Rukai tribe and close to 100,000 tourists visit the area every year after a parking lot and visitor's center was built.
Dangers to habitat
Butterfly specialist Chen Wen-Long estimates that over 200,000 purple butterflies perch there in winter and he reports that three-eighths of the gorges have been damaged by human activity. Mikania micrantha H.B.K., a species of vine from Central America, has caused damage to the region and Chromolaena odorata, a type of thick, tall grass from the tropical regions of the Americas has caused problems for the indigenous plant life. Additionally, reports of human trapping have reduced their numbers.
Scientists use the term "butterfly gorge" to refer to migratory patterns of Taiwanese butterflies, rather than actual geographic locations. There art three types of these gorges: "migratory butterfly gorges," "ecological butterfly gorges," and "pathway butterfly gorges."
Purple Butterfly Valley is a "migratory butterfly gorge" and it is one of the three most butterfly-populace of gorges. The other two are in southern California and Mexico. Butterflies return from the "migratory butterfly gorges" in May and June to what are referred to as "ecological butterfly gorges."
In spring and summer, the butterflies hatch from their cocoons and feed on flower pollen in habitably warm mountainous regions. More than tens of millions of various butterflies, mostly of the species Eupatorium shimadai Kitamura find comfort on Datun Mountain in the Yangmingshan range in Taipei County. The best time to observe them is in June.
Hundreds and thousands of butterflies visit the "pathway butterfly gorge" in the mountainous region of Wulai in Taipei County and the Meinong region of Kaohsiung County. Papilionidae, Pieridae and Lycaenidae butterfly families may be found in these gorges seeking watering holes on either side of the rivers and stream passageways. It is believed that sulphur in the water helps male butterflies develop their sexual maturity.
Dance and flight
The gorgeous flight pattern of butterflies is likened to dance, and authors, poets and choreographers make allusions to them. In fact, the Rukai tribe has a dance with elegant and measured steps inspired by this behavior.
The Butterfly Conservation Society of Taiwan has published a pamphlet entitled "The Dance of Butterflies" carefully explaining how the 10 families and 127 separate species may be observed right in the confines of Taipei City at the city zoo.
Reading further reveals information about the dancing of butterflies throughout the climactic regions of Taiwan's 36,000 square kilometers of area.
Life and climate
Most of Taiwanese flatland is heavily populated by people, making it difficult for their subsistence. Tropical coastal regions such as Kending National Park are good resting places for the species that prefer warmer, drier weather, but pristine tropical forests, located at elevations of under 500 meters are more conducive for butterfly inhabitation while sub-tropical regions have been subject to greater damage and temperatures are cooler, ranging on average between 13 and 22 degrees. Conservation work is necessary to allow butterflies to inhabit the subtropics.
Larger butterfly species are capable of weathering the cooler forested temperate regions above 1800 meters in elevation. Higher in the subarctic mountains, very few species may be found, but they can be found among arrow bamboo groves.
The purple butterfly is actually brownish in color. It is a large fritillary with a wingspan of 8.5-10cm. Males have blackish-brown wings with whitish-brown spots on its cells, especially in the center of its forewings, which are covered with white spots. The centers of both its forewings and hind wings shine with a purplish, metallic luster. The wings of females are also blackish-brown in color, but are larger than their male counterparts and lacking in the purplish, metallic luster.
The larvae of purple butterfly feed on the leaves of the Celtis sinensis and pass through six instars, or insect phases, before becoming adults. They spend most of the winter in larva form under fallen leaves and turn into pupa during the spring, at which time they will attach themselves to leaves, leafstalks, or nearby plants.
Adults emerge between May and August, breed only once per year, and diet on tree sap and the juice of mature fruits. Purple butterflies live in the mountainous regions of central and northern Taiwan, especially in Balin on Lala Mountain and Jianshi and Wufeng on Jiaoban Mountain, but they migrate to Purple Butterfly Valley as mentioned above.
By observing this migratory pattern, researchers can best learn how to preserve the butterflies. During the warm months, volunteers mark butterflies' wings so that they may record which butterflies they track when they return to Purple Butterfly Valley.
The information for this article was sourced for the most part from the Purple Butterfly Valley Web site: http://e-butterfly.nchc.org.tw.