Ask Lafeber


July 30, 2021

Hormonal weight gain?

Is there anything known about female parrot weight year cycle? I have an adult female blue headed pionus and she gains weight every spring (when the daylight hours increase) and then decrease again in weight less starting from mid-summer. I have made a excel -diagram for her weight spanning several years and it is the same cycle every year. She eats the same amount and same type of food all year round. Can it be hormonal that she gains weight in spring?


Hi Helena,

Here is a response from Dr. Stephanie Lamb:

Yes, I have seen birds that routinely gain weight during the breeding season and then lose it afterwards. This is something that should be happening in a normal cycle if she were in the wild so it’s not abnormal at all for it to be happening in captivity. The reason it happens is because in the spring time when hormones are high the reproductive tract increases in size substantially. The extra weight is actually just an enlarged oviduct and ovary. The same thing happens with males and they will gain weight because the testicles increase in size.

Thank you for asking Lafeber,


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