News Excerpt: 

Butterfly migration from the Eastern Ghats and plains towards the Western Ghats was below par this year.

About Butterfly Migration:

• The butterflies are bioindicators. Studying the annual seasonal butterfly migration is important for tracking climate change-altering weather phenomena.

• Seasonal butterfly migrations in India:

• Every year, two seasonal butterfly migrations occur between the Western and Eastern Ghats of the Indian peninsula in search of food and survival.
• The butterflies originate from Western Ghats ranges, such as Kodagu, Wayanad, Nilgiris, Siruvani and Anamalai, and move toward the Eastern Ghats consisting of Yercaud, Pachamalai, Kolli, and Kalvarayan hills during the first migration. And back for the second migration.
• First- It begins in May and June, before the onset of South-West monsoon. The butterflies migrate from the Eastern Ghats to the Western Ghats. The first migration is to avoid intense rain, which makes their survival difficult.
• Second- It begins in September before the North-east monsoon starts in the Eastern Ghats. During this time, they migrated back to the Western Ghats from Eastern Ghats.

• Factors impacting the butterfly migration: 
  • Changes in Climatic Conditions- Climate change has significant potential to alter butterflies' migration, hibernation and reproduction.
  • Rainfall - A Good migratory movement is observed when the rain is in excess.

Highlights of the observations from The Nature and Butterfly Society (TNBS):

• It shared the data with 'Butterfly Migration India', a portal to collate information from all states. 
• Before the onset of the Northeast monsoon, butterflies from the subfamily Danainae, such as Blue Tiger, Dark Blue Tiger, Double-branded Crow, and Common Crow (commonly known as 'Tigers and Crows'), leave the Eastern Ghats and fly towards the West. However, observers have seen only a low-scale migration of Tigers and Crows since September this year. 
• Many of the regular routes over which the migration is usually observed did not see any movement. This is likely due to below-normal rainfall in west zone districts.
• TNBS observers also noticed the local movement of the Common Albatross (Appias albina), a butterfly species from the family Pieridae, in large numbers from the low to mid-elevation of hills of Anaikatti and the Nilgiris towards the Sirumugai forest range and Sathyamangalam Tiger Reserve.

Prelims PYQ:

Q. Recently, for the first time in our country, which of the following States has declared a particular butterfly as ‘State Butterfly’? (UPSC 2016) 

(a) Arunachal Pradesh

(b) Himachal Pradesh

(c) Karnataka 

(d) Maharashtra