A theory...

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spanna
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Hi gang

Looking for opinions on a theory of mine regarding crimsons.
I know as a general rule crimsons aren't kept in large numbers, and usually only in lightly stocked aviaries, but due to space restrictions and a placid nature my pair are in with a number of other birds in a large planted aviary. First clutch was 6 birds, unfortunately I lost the runt at the start of its moult, though the others are going great. They had another nest of only 1 bird, then a nest of 6 eggs that got fried in a heat wave (4 days over 42 in a row!), and now sitting on another 6 due in a little while.

So, breeding birds, not so unusual, but of the 6 chicks I have so far 1 is definitely a cock, 4 are definitely hens and I'm fairly sure the sixth is also a hen.

My theory is that as the pair has more competition, the gender ratios are skewed in favour of producing hens. I know research has been done with zebra finches that showed more females to be produced under more stressful conditions, do others have any similar experiences??

Please note, while I say "more stressful conditions", my birds are in no way stressed or wanting for anything!!
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Craig52
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spanna wrote:Hi gang

Looking for opinions on a theory of mine regarding crimsons.
I know as a general rule crimsons aren't kept in large numbers, and usually only in lightly stocked aviaries, but due to space restrictions and a placid nature my pair are in with a number of other birds in a large planted aviary. First clutch was 6 birds, unfortunately I lost the runt at the start of its moult, though the others are going great. They had another nest of only 1 bird, then a nest of 6 eggs that got fried in a heat wave (4 days over 42 in a row!), and now sitting on another 6 due in a little while.

So, breeding birds, not so unusual, but of the 6 chicks I have so far 1 is definitely a cock, 4 are definitely hens and I'm fairly sure the sixth is also a hen.

My theory is that as the pair has more competition, the gender ratios are skewed in favour of producing hens. I know research has been done with zebra finches that showed more females to be produced under more stressful conditions, do others have any similar experiences??

Please note, while I say "more stressful conditions", my birds are in no way stressed or wanting for anything!!
Hi spanner,i only run one pr per aviary (8 pr)on their own,no other birds so no competition. Three years ago i bred 16,12 hens and 4 cocks.Last year 16 also but lost 4 nests of 4 young due to the heat so can't comfirm the sexes but out of the 16 there was 11 cocks and 5 hens.
This year after loosing three nests of young (not counted) i have bred 10 so far,5 hens and 5 cocks so i don't think there is any recipe for more of this or more of that.As i write this there are a few prs with young in the nest so my averaging might be completely wrong but i am taking these averages from 8prs,not one pr.I could go out and count the ring colour of the young and find out the sex ratio from that pr but i'm pretty sure if they had 4 young they are 2 cocks and 2 hens.
I was beginning to blame the weather for the odd sex ratio but when i work it out,the weather has been much the same for the last 3 years so incubation temperatures (like some birds,crocodiles etc) haven't determined the sex of the young this year so far but time will tell i suppose.
This is a very interesting topic and in a month or so i will work out what each pr produced sex wise and post the results. Cheers Craig
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casehulsebosch
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Remember Craig that Catherine Young - of Gouldian count and Sarah Pryke fame - is doing her PhD on the crimson.

She should come up with some interesting date both in the wild and in captivity in the future.


cheers, Case
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BrettB
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I find this a fascinating topic, and there is lots of data to show that sex ratios can be altered by environmental factors, so why not Crimson's ?

The difficulty is getting good data with sufficient power (large enough numbers) to take out all the variability related to chance.
Please note, while I say "more stressful conditions", my birds are in no way stressed or wanting for anything!!
Which is one of the issues, how do we measure how much stress our birds are under, short of taking blood samples for cortisol levels.
Is living in a cage with some friends more stressful than starving, flying 20 km to water, dodging predators, or a myriad of other events that befall "unstressed" wild birds.

Cheers
Brett
"We don't see things as they are, we see things as we are ." Anais Nin
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Diane
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Location: Northern 'burbs of Adelaide

If you saw the recent giraffe item on the news in a Danish Zoo. (Disgusting attitude by a zoo, but thats another story) the reporter on the ABC news report I saw said that environmental factors such as a good food source tended to produce more male young and this can be seen to happen in the wild too. So if a seasonal change like that can have an effect on such a large animal as a giraffe then I would tend to agree the same would happen with birds.



I dont want to hijack spanna's topic with comments about the Zoo so.....
For those that would like to see the news footage.............BUT BE WARNED ITS NOT PLEASANT
I have out the link in the topic Gregh started.

viewtopic.php?f=48&t=8406&p=141817#p141817
Diane
The difference between Genius and Stupidity is, Genius has it’s limits
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spanna
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Further update:

My theory seems to be shot to pieces... :lolno:
Last clutch I removed a while back, 5 chicks, all boys. There goes that gender ratio straight out the window! Luckily I know a good wildlife park with some top notch bird keepers (ie me and my workplace :lol: ) that were happy to take 4 bright young boys.

Back to the drawing board, and have 2 more pairs to play with this spring too!
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TomDeGraaff
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casehulsebosch wrote:Remember Craig that Catherine Young - of Gouldian count and Sarah Pryke fame - is doing her PhD on the crimson.
She should come up with some interesting date both in the wild and in captivity in the future.
cheers, Case
Maybe this lady can expand her brief to include the pale crimson ??
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Niki_K
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spanna wrote:Hi gang

Looking for opinions on a theory of mine regarding crimsons.
I know as a general rule crimsons aren't kept in large numbers, and usually only in lightly stocked aviaries, but due to space restrictions and a placid nature my pair are in with a number of other birds in a large planted aviary. First clutch was 6 birds, unfortunately I lost the runt at the start of its moult, though the others are going great. They had another nest of only 1 bird, then a nest of 6 eggs that got fried in a heat wave (4 days over 42 in a row!), and now sitting on another 6 due in a little while.

So, breeding birds, not so unusual, but of the 6 chicks I have so far 1 is definitely a cock, 4 are definitely hens and I'm fairly sure the sixth is also a hen.

My theory is that as the pair has more competition, the gender ratios are skewed in favour of producing hens. I know research has been done with zebra finches that showed more females to be produced under more stressful conditions, do others have any similar experiences??

Please note, while I say "more stressful conditions", my birds are in no way stressed or wanting for anything!!

Actually, zebra finches are the little weirdos of the bird world, and are more likely to produce a male-biased primary sex ratio (by this, I mean at fertilisation) under less than optimal conditions (e.g. high predation risk, poor nutrition etc). This is thought to be due to the fact that females that experience early developmental stress are less fecund later in life. In most other species, it's the other way around, as males tend to be more 'expensive' for mothers to produce, as they need more parental resources to be successful later in life, in terms of survival and being competitive enough to attract a mate.
EDIT: I should state though, that it generally depends on what the stressor is, and how long the mother is exposed to the stressor, as that alters results.
Last edited by Niki_K on 25 Jul 2014, 20:04, edited 1 time in total.
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Niki_K
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Which is one of the issues, how do we measure how much stress our birds are under, short of taking blood samples for cortisol levels.
Is living in a cage with some friends more stressful than starving, flying 20 km to water, dodging predators, or a myriad of other events that befall "unstressed" wild birds.

Cheers
Brett[/quote]

You can't- not until feather corticosterone (the primary avian stress hormone) has been properly researched and quantified in songbirds. I'm hopeful, but Deakin researchers have been working on it for a couple of years with no success. Sadly, faecal measures of corticosterone have proven useless thus far- probably because their lag time (i.e. from eating to pooping) is so short.
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