Why do birds sing on spring ?

Around the end of the Nepali year, I heard the mesmerizing sounds of the Asian koel bird echoing in the air while returning from college. My heart filled with excitement.  It was the first time I heard a koel singing this spring. Even more, I thought I was the first to hear its delightful tunes. I shared the thrill with one of my senior, a bird expert.  He laughed and corrected me. “Bro, it started singing since last month,” he stated. 

I was a little disappointed. But to my delight, the song will stay abuzz for the rest of spring.  However, have you ever wondered why you hear the koel singing only during spring? How do they even know that its spring? 

In spring, days are longer compared to winter. The warmer days activate hormones in the birds allowing them to know that its spring. 

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Spring, for them, is seasons of possibilities. The season also ensures plenty of food acting as a stimulant for mating.  

Male birds sing to attract their female counterparts, and also to mark territories. However, bear in mind that calls and songs differ from one another. Calls are usually short and are used to alarm other birds from possible danger. On the other hand, songs are elaborated and rhythmic.

Birds usually sing in the morning, calling out probable partners in distant territories. Songs are mainly used for breeding. Even between birds of the same species, there is slight tonal variation. The variations help females distinguish between males. Female birds also choose their males for breeding. The distinct song is the deciding factor in establishing dominance over other males, and transferring genes. 

In spring, songs of Asian koel can be very pleasant to the ears. Males sing and females respond accordingly. However, in the city, sound pollution makes it difficult to hear the koels singing. Nonetheless, open spaces still buzz with melodious songs of other bird species like the oriental magpie-robin. Take some time out to be a part of the magic of spring. 

Pal is currently studying masters in zoology from Central Department of Zoology, Tribhuvan University.