In Korean politics, “migratory birds” is a term used to refer to politicians who change their party affiliations in pursuit of short-term political interests, like obtaining nominations or increasing their chances of winning an election. The migration becomes brisker ahead of major elections.

The upcoming April 13 general election is no exception. In fact, the phenomenon has become more serious partly because of the launch of the People’s Party, which was set up by figures who had broken away from the main opposition Minjoo Party of Korea.

What’s more intriguing is that some candidates and politicians dare to cross political and ideological lines.

The latest case is Kang Bong-kyun, a former technocrat who assumed the post of cochair of the ruling party’s campaign committee Wednesday. Kang served as the finance minister and a Blue House senior aide during the Kim Dae-jung administration, and he was elected to the National Assembly three times, on the ticket of the Minjoo Party’s predecessor.

This means a man who was a key member of the liberal political force for decades has now taken the helm of election campaign for its perennial archenemy.

In the Minjoo Party, it was just as puzzling when the liberal party brought in Kim Chong-in as its stopgap leader. Kim started his public service under the Chun Doo-hwan administration and remained in the conservative bloc until he served as the chief architect of Park Geun-hye’s election pledges for the 2012 presidential poll.

Those who have followed politics for long may well be confused seeing Kang under the Saenuri banner and Kim under the Minjoo banner. Yet, the public does not seem to be as critical of them as it has been of other migratory birds, turncoats, chameleons, apostates or whatever you may call them.

This is partly because Kang, while belonging to the liberal political group, had advocated some conservative policies -- like support for growth led by conglomerates and selective welfare -- whereas Kim had supported things like “economic democratization,” which called for reining in the concentration of wealth at big firms.    

This is why some argue that Kang and Kim are at last in their rightful homes, and that they will be able to bring the rightist and leftist parties a little further toward the middle of the ideological spectrum. 

If their case has such a positive aspect, that of other migratory birds -- like Chin Young -- only deepen the already serious public distrust of politicians. 

Chin bolted from Saenuri in protest over the party’s decision to deny him nomination and joined the Minjoo Party, which readily gave him the ticket for the constituency in Yongsan, central Seoul.

It is true that Chin was one of the victims of the Saenuri Party’s internal power struggle in which the faction loyal to President Park Geun-hye purged people who were critical of the president or alienated from her.

But few would have agreed with Chin when he said that he jumped ship because the Saenuri Party is a “clique controlled by a certain person,” in apparent reference to Park. Reelection might be a matter of life and death for Chin, but it is truly uncomfortable to hear a man who served Park -- first as her chief of staff when she was the party leader and then her first health and welfare minister -- lambast his former boss and the party on whose ticket he was elected to the parliament three times.  

It would have been much better if Chin had decided to run as an independent. Instead, he defected to what had been his party’s chief enemy solely to retain his parliamentary seat. People like Chin say all the nicest things to justify their actions, but voters should keep cool heads and isolate migratory birds carrying the virus of personal greed from the political habitat