Answer:
The graph shows that Golden Crowned Kinglets have been spotted sooner every year, and it appears to be a stable rate.
It could be due to several reasons, but a good hypothesis is that the Golden Crowned Kinglets is a migratory bird and because of climate change, they are starting to migrate sooner.
Explanation:
The graph shows us that in the 70's the Golden Crowned Kinglets were usually spotted around mid May. However in the early 2000's, they were seen as soon as late April or Early May. While the change may not seem so drastic, the birds have been spotted sooner and sooner at a very stable rate, indicating that the birds will continue to show up sooner.
Without information on the bird's habits it's hard to provide a good hypothesis, but since we are recording the first sighting in spring, we can reasonably assume that the Golden Crowned Kinglet is a migratory bird, who arrives in the spring. Since climate change has been increasing temperatures in some places and decreasing them in others, it's possible that the birds are receiving environmental signals to migrate sooner and sooner.
