Uk juvenile Bittern? (1 Viewer)

[Mahsleb]

Hi all, I spotted the Bittern on the right standing in the reeds,
then the other one flew in and landed nearby, both disappeared and then
reappeared a little later close together. The one on the right of the pic seemed
noticeably smaller, much lighter in colour and less clearly marked
Could it be a juvenile or is it too early for one this size?
I see Bitterns fairly often but this one definitely looked different
Thanks for any help

 

[phil baber]

The brownish cast to the crown and moustachial stripe would suggest that it is a juvenile. Also the moustachial stripe is much reduced compared to the adult behind. Another juvenile feature.

Bitterns don't tend to like each others' company. This would also suggest this to be a female with her well grown young. (As males take no part in rearing of the young.)

Only my opinion. But it feels right to me.

Other opinions are available!

Fantastic shot BTW!

http://www.jstor.org/pss/4132555

 

[Mahsleb]

Thanks Phil, my thoughts too, but I was unsure as i've not seen one like it before,
maybe someone else will confirm this

cheers

 

[phil baber]

Very little info is available online about juvenile Great Bittern. (Unless you wish to pay for it!)
But from what I gather, the above info is correct. And you captured a Mother and her juvenile offspring...
I bumped this because I know BWP is in the library in Town, and is closed...
Hoping someone can link us all to definitive information on young Great Bittern...

I have never knowingly seen one. And, your photo could be very important. Just try a search to find another photo of a juvenile GB?

Yours is the only photo I have found so far..!:t:

 

[phil baber]

(As males take no part in rearing of the young.)

Apparently, some males do in the early stages, I have found out.

 

[Mahsleb]

Thanks Phil, I'm surprised there hasn't been a bit more interest in this, here's another shot of the bird

I've emailed the photo and details to Minsmere to see if it's of use to them

regards

 

[PYRTLE]

I understand also that eye / pupil colour can assist in ageing a bird, also, from a very experienced warden who has observed a male assiting in feeding young.

 

[OlaB]

The brownish cast to the crown and moustachial stripe would suggest that it is a juvenile. Also the moustachial stripe is much reduced compared to the adult behind. Another juvenile feature.

Bitterns don't tend to like each others' company. This would also suggest this to be a female with her well grown young. (As males take no part in rearing of the young.)

Only my opinion. But it feels right to me.

Other opinions are available!

Fantastic shot BTW!

http://www.jstor.org/pss/4132555

What Phil is describing above is exactly the best fetaures for a positive id of a juvenile Bittern. Add the very pale underparts and there shouldn't be any doubts.

Regarding eye colour I don't think that is a feature easily used (I've never heard about it before but that doesn't mean it's for sure ;-)

 

[Mahsleb]

I understand also that eye / pupil colour can assist in ageing a bird, also, from a very experienced warden who has observed a male assiting in feeding young.

What Phil is describing above is exactly the best fetaures for a positive id of a juvenile Bittern. Add the very pale underparts and there shouldn't be any doubts.

Regarding eye colour I don't think that is a feature easily used (I've never heard about it before but that doesn't mean it's for sure ;-)

Thanks Pyrtle and thanks Ola, your input is appreciated!

 

[ben_lewis]

I have heard that the ONLY way to tell a juv from an adult is by the pale iris. It stays pale for 1-2 weeks after they fledge the nest and then darkens or yellows. As has been said its a very difficult feature to see. I think the iris should be a pale washed out sandy yellow/beige colour on juv.
Although that is the main id feature to guarantee a juv, another good pointer is that their feathers are usually very contrasting, bright and 'pristine' looking, certainly in comparison to the adult females which will show a slightly bedraggled look after feeding young for c.50 days.
As usual with bitterns there is a limited amount of knowledge on the subject, Collins field guide does not even differentiate between males and females.

 

[OlaB]

I have heard that the ONLY way to tell a juv from an adult is by the pale iris. It stays pale for 1-2 weeks after they fledge the nest and then darkens or yellows. As has been said its a very difficult feature to see. I think the iris should be a pale washed out sandy yellow/beige colour on juv.
Although that is the main id feature to guarantee a juv, another good pointer is that their feathers are usually very contrasting, bright and 'pristine' looking, certainly in comparison to the adult females which will show a slightly bedraggled look after feeding young for c.50 days.
As usual with bitterns there is a limited amount of knowledge on the subject, Collins field guide does not even differentiate between males and females.

I don't have any literature with me but I'm pretty sure that the brown cap and moustachial stripe are good features. Can't remember that there are any major differences between male and female either (other than size/wing length)? Please enlighten me if I'm wrong.

 

[Mahsleb]

I have heard that the ONLY way to tell a juv from an adult is by the pale iris. It stays pale for 1-2 weeks after they fledge the nest and then darkens or yellows. As has been said its a very difficult feature to see. I think the iris should be a pale washed out sandy yellow/beige colour on juv.
Although that is the main id feature to guarantee a juv, another good pointer is that their feathers are usually very contrasting, bright and 'pristine' looking, certainly in comparison to the adult females which will show a slightly bedraggled look after feeding young for c.50 days.
As usual with bitterns there is a limited amount of knowledge on the subject, Collins field guide does not even differentiate between males and females.

Thanks Ben, so you think it's an adult?
The eye does look dark in both photos, but the plumage certainly looks
"bright and pristine" as well as unusually pale in colour

I don't have any literature with me but I'm pretty sure that the brown cap and moustachial stripe are good features. Can't remember that there are any major differences between male and female either (other than size/wing length)? Please enlighten me if I'm wrong.

Thanks Ola,I was under the impression there's a difference in colour at the
base of the bill in breeding males and females, but I could be wrong!

 

[OlaB]

Thanks Ben, so you think it's an adult?
The eye does look dark in both photos, but the plumage certainly looks
"bright and pristine" as well as unusually pale in colour



Thanks Ola,I was under the impression there's a difference in colour at the
base of the bill in breeding males and females, but I could be wrong!

Iris is yellow in both juvenile and adult (I have never heard of a difference here). It looks dark in one of the pictures but that is just a matter of angle and light.

I would still argue that it is a juvenile based on the apparent brownish head and moustachial (it's light plumage not contradicting this either).

I've never heard of a difference in base of the bill but I would be glad to be proven different regarding all I say. ;-)

 

[arry02]

hi all , so basically youve nailed a rare photo indeed , we need to get back out when i get back cracking shot mate .

 

[Simmo1111]

I'm currently monitoring breeding bitterns and the 3 juvs have now reached the point where they have more or less fledged. I'm aware of the difference in the colour of the crown and the moustachial stripe but to be honest, even with the juvs in the scope, it's a sometimes real pig to try and see the difference! By the way, the male bird has blue lores when he is in the breeding period and it stands out very well if you ever see it.