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I might get myself 2 pairs, red heads and black heads and do my own little experiment.....Probably of no use whatsoever to your study......but I was reading the International Express and found a small piece of interest.Niki_K wrote:Let me point out that when I say 'stress', I'm really referring to circulating stress hormones.
Stress link to girl babies.
Women who are stressed while trying for a baby could be more likely to have girls.
In the first of its kind, a study found high levels of the stress hormone cortisol were associated with the birth of more girls than boys.
Some 338 British women who were trying to get pregnant recorded how stressed they felt. Levels of cortisol and the enzyme alpha-amylese - an indicator of adrenalin- were measured for up to six months or until they fell pregnant.
Cortisol is linked to long term stress, while adrenalin is linked to short term stress.
A team from the Department of Public Health at Oxford University found women with the highest cortisol levels were up to 75% per cent less likely to have a boy. No link was found with alpha-amylese.
The experts, who are presenting their findings at the American Society for Reproductive Medicine conference in Orlando, say more research is needed to see if the link between stress and sex ratio is genuine.
A little stress could be helpful next time round to even things up a bit. 
I breed only wild type normals and keep head colour separate. I get good coloured faces on the hens with little smuttiness. My orange heads occasionally throw a black head with yellow tipped beak and my red heads sometimes have a black head or an orange head. Go figure that out.That's similar to what I'm working on, just with zebbies insteadbluebutterfly213 wrote:@ Nik_KProbably of no use whatsoever to your study......but I was reading the International Express and found a small piece of interest.Niki_K wrote:Let me point out that when I say 'stress', I'm really referring to circulating stress hormones.
Stress link to girl babies.
Women who are stressed while trying for a baby could be more likely to have girls.
In the first of its kind, a study found high levels of the stress hormone cortisol were associated with the birth of more girls than boys.
Some 338 British women who were trying to get pregnant recorded how stressed they felt. Levels of cortisol and the enzyme alpha-amylese - an indicator of adrenalin- were measured for up to six months or until they fell pregnant.
Cortisol is linked to long term stress, while adrenalin is linked to short term stress.
A team from the Department of Public Health at Oxford University found women with the highest cortisol levels were up to 75% per cent less likely to have a boy. No link was found with alpha-amylese.
The experts, who are presenting their findings at the American Society for Reproductive Medicine conference in Orlando, say more research is needed to see if the link between stress and sex ratio is genuine.
If my theory is correct, my stressed mums should produce more males than females, as zebbies (of course) are the opposite to every other species haha! For some reason, they produce more males if the mother is in 'poorer' condition (and I use that term loosely- it could be due to nutritional deficiencies, her size/quality, even linked to her own brood size as a nestling), whereas in other species, mums tend to produce more females under those circumstances. Generally, mum has to be in good condition to produce more boys, as they need more energy from her (as they're usually a bit bigger and have brighter colours, which are energetically 'expensive').I use stress hormones directly, but other people have used scaring the mums (one of my collaborators is using kookaburra models and throwing them past the aviaries haha), or limiting her food intake (i.e. food stress), or giving her an unattractive mate. Sex ratio can be biased depending on how far into the season it is. I think parrots and some other birds produce more males early in the season, and more females later in the season.jusdeb wrote:Very interesting ,now any hints on how to stress these birds ? I have 7 parrots inside for hand rearing and they are all boys
The other birds tell herTintola wrote:Can anyone answer how the hen knows what head colour she is herself ?
