What determines seasonal molting/migrating

[Snipes]

Is it temperature or photo period?

 

[StevenW.]

I'm guessing it has to do with Temperature and How many hours of light we have in each day since it changes each season.

I really can't answer it any better than that unless I go on google and look around. This is a very interesting topic! Thank you for bringing this up!

 

[Speceider]

A vague question because the strength of stimuli varies among species. Generally,forobligant migrants, photoperiod controls the endocrinology that triggers molt and migration. Proximate factors vary even more among species and individuals. For example, mallards tend to molt starting in May and June, but if a drake doesn't pair, he won't molt until later. With migration, zugenrhue starts in response to photoperiod, but actual departure is dependent upon weather conditions, bird body condition, disturbance, etc.

Clint