Do different species of birds understand each other's tweets?

This week's question comes to us from Virginia Baldwin of West Vancouver, British Columbia. She asks:

Listening to the chorus every morning from a wonderful variety of birds I have around my home, I was wondering if one bird type can understand the songs of another?

Brendan Boyd, a PhD student in the Department of Biology, and the Stutchbury Lab for Behavioural and Conservation Ecology at York University explains there are two types of bird vocalizations, a song and a call. A song is usually longer and more complex than a call. It is used for attracting a mate or for defending territory.

A female listens to this song to determine the quality of her prospective mate. Other males also listen to the song to assess quality, but in this case to see if it is worth challenging the male for his territory. While this is important information for the species doing the singing, it is not understood by other species; there is no competition for mates or territory. 

While this is the case for songs, bird calls are another matter. Most species have a variety of calls they use to communicate with each other, but other species can take information from them. Specifically, these types of calls are alarm calls warning of predators or other dangers.

These types of calls elicit a strong response from unrelated species. In a study involving the 'chick-a-dee-dee' alarm call of the black capped chickadee, a total of 24 unrelated species showed up to investigate the reason for the alarm.