Waxwing calls and sonogram

As well as superb views and the sight of tens or even hundreds of Waxwings has been superb over the past couple of days, the constant calling and sound of the trilling above the urban traffic has been the highlight for me.

The calls can be heard here on a sound recording I took today in B&Q car park.:-

http://www.youtube.com/watch?v=Y2-clvqxk0I&feature=channel&list=UL

Look at this amazing sonogram of the calls. The trill is made up of up to 10 very fine notes a second. Click on the image to make it larger.

I've played around with the sound this evening and slowed it down to various fractions of its speed so you can hear all the notes the trill contains. Listen to this clip where I have slowed it down to just under half its original speed. You can hear how many notes those high pitched short trills contain.

http://www.youtube.com/watch?v=l6PqTaN9Cbs&feature=youtube_gdata

I always wonder how birds hear each others contact calls. Do they sound just like we hear them or are their ears far more sensitive to bird calls and hear a range of 'vocabulary' in what we hear as a trill, a rattle or a whistle. All interesting stuff.