The reason I was drawn to it was that the bird's cycles are continuous and so the circle expresses this better than a time-line. It is also hemispheric neutral in that time-lines start in January and finish in December and so for Southern birds their breeding season, for example, might cross the December and January year boundary and so, for those birds you would not see a continuous line but a line in two segments
Jan Feb Mar Apr ... Oct Nov Dec
nesting ------- -------
It is also similar to the situation awareness visuals I have seen  and very much like.
Learning how to read this visual is not difficult and so a short audio training might be used. For example, this NPR story  is about the movie High Noon's title song and how its elements were repeated in the movie's score. Towards the end of the story there is a short segment of the score featured with overlaid commentary. It is a stunningly informative information presentation. At least to this musical klutz.
 "Visual Correlation for Situational Awareness" http://www.sci.utah.edu/publications/yarden05/VisAware.pdf
 "High Noon"