Baby Seagull - Santa Cruz neighborhood

Hello 

We had several Families of Baby Seagull - Santa Cruz neighborhood 

Most of the Babies have flown away and left the Roof tops of our homes 

Except for 1 , the parents are still on the Roof with the baby and present only just not feeding the baby 

The baby is not flapping it's wings or attempting to fly any more  originally did fly and was following siblings 

Does not seem to be hurt in any way and wings do not look as if injured , just not trying to fly anymore ? 

Is this Baby Seagull possibly hurt and why it is not leaving the Roof ?

How long should I wait before contacting a local agency to see if Baby should be removed from the Building Roof ( behind my house) ? . 

Any advice appreciated 

Erica from Santa Cruz