Indeed, Michael is right. I am a native speaker and I needed to check a dictionary--and I have a degree in zoology! I was actually surprised to find it in an ordinary dictionary.
ahdictionary.com gives these definitions.
1. The scientific study of periodic biological phenomena, such as flowering, breeding, and migration, in relation to climatic conditions.
2. The timing of a periodic biological phenomenon in relation to climatic conditions.
Get in the habit of using a dictionary... and often Wikipedia is better than a dictionary.