there is no answer the birds just know when to go
a very early fall frost
It is a limiting factor.
A limiting factor
Abiotic factors such as temperature or rainfall are not density-dependent factors limiting population growth. These factors do not change in intensity depending on the size of the population.
sunlight.
Early Birds - 1923 is rated/received certificates of: UK:A
No because birds get up early too and some birds are nocturnal.
The cast of The Early Birds - 1968 includes: Joan Gerber Jonathan Winters
Flightless
"Limiting factors:Female red pandas give birth mainly in June. Mating occurs during winter, usually between early January and mid-March, another factor is that they are endangered and shy. And habitat loss." Quote taken from https://sites.google.com/site/biologybfinalproject/animalia/red-panda-ailurus-fulgens
depends on the bird
cause worms come out early