Being rather sad and anally retentive about my local patch birdwatching, I databased all 60,000 or so observations that I have made over the last 25 years at Red Rocks, Merseyside. One of the nice things about covering an area for so long is that you get really nice believable graphs.
This set shows the difference in passage patterns between closely related species. Tree pipit is almost 100% a spring bird, Meadow Pipit and Yellow wagtail show a slight spring bias and Grey wagtail is an autumn species. I'd be interested to hear any theories.
This set shows the difference in passage patterns between closely related species. Tree pipit is almost 100% a spring bird, Meadow Pipit and Yellow wagtail show a slight spring bias and Grey wagtail is an autumn species. I'd be interested to hear any theories.