There wasn't an exact time, they kind of just disappeared eventually. But it happened somewhere between seasons six and seven. That I'm sure of. :)
posted پہلے زیادہ سے سال ایک
no,,they were when Rachel moved in to Joey in the sixth season,, raschel say's like "what the helld did damn بتھ, مرغابی do now" and Joey says" Well it did not eat your facecream" so it was between the sixth and the seven season :]
in the season 10 joey buys a chick and a بتھ, مرغابی to give as a present to Chandler and Monica.Phoebe asks"there are chicks and بتھ, مرغابی in the world now!" then rachel says " didn't they die..(phoebe interupts) pheobe says"thay dive"
its like that the birds they had before ate the facecream got sick and chandler took them to the hospital and it died.joey mentions that " when آپ grow up u will go to the place where other chick and بتھ, مرغابی went too.shame we cant go there"
so that means chandler lied to him.if آپ don't get what i mean just watch the last 2 episodes of friends.check 5:13 of the video.