Latvian WtE nest webcamera Juras-erglis: Discussions

[Sonchik]

Suddenly this is our Mr. X with an injured right leg?
https://www.looduskalender.ee/forum/vie ... 23#p797323

[Sonchik]

Apropos their wide spread wings: Do I remember rightly that you once said you liked watching the eagles soar? It's not a WTE, so I posted it elsewhere, but this is a really nice video of two predators (Golden Eagle and Bearded Vulture) soaring (and there are more by the author on yt):
https://www.youtube.com/watch?v=3Z5OLAa55yY

It's spellbind. Thanks!

Interesting idea. So he might sort of have felt his own eggs were under threat from a stranger when he saw Mr Silver on the nest?
It sounds appealing. But how did he find this nest so quickly? Or would he have attacked just any nest to get back on eggs so to speak?
I also wouldn't underestimate his dive-bombing talent and his speed, as well as especially his extremely high manoeuvrability. Like rebelde, I could imagine that that was an advantage of his being potentially slightly smaller than Mr Silver.

I think this mystery will remain unsolved. We can only speculate.

[ame]

13:47 Both on the nest.
Milda has a fuller crop than the stranger. So have those morning conversations Sonchik keeps reporting on already born fruit? Did he pass on his catch to her?

why to make notes of observations in the discussion topic? it is a wrong place (although there were some speculations as well.)

if this trend will continue i shall start to move posts from here to the observation topic.

[Ajeta]

why to make notes of observations in the discussion topic? it is a wrong place (although there were some speculations as well.)
if this trend will continue i shall start to move posts from here to the observation topic.

This was not a post announcing an observation. I gave the time stamp of the event I was going to discuss, as it was agreed on here a while ago so that other people can look up the event for themselves to understand better what a post is talking about.
In doing so I used my common sense, as recommended recently by you, and followed your rules as stated here:
https://www.looduskalender.ee/forum/vie ... 16#p789316

[Ajeta]

me too, i would have been happy seeing Milda and Mr C as the new couple, but...
everyone should get his fair chance

balistar, I wanted to say that I am truly sorry for you as well as all the people who in Mr C lost their favourite now to another. (Lost as in he's not here anymore for the time being - we do not know more, after all.) I know precisely how you feel as I was in that situation myself when Mr C ousted Mr L on April 8th. Anyway, noone knows what else will happen, neither we nor Milda get to chose who aquires the position of the male here.

[rodjur]

For sure Mr L is not Raimis? Sorry, I know it is an absurd question, but it is soo strange to me that Milda can change so quickly a partner. Sometimes I think that Raimis was not the first one for her, she seemed really experienced. And now I can say that she is very modern :) let's see what will happen, but she is really a very strong and special female!

[Ajeta]

Ame just posted a spectacular example of why tail marks can - besides being a help in identifying - also cause confusion, especially when one does not know an eagle yet and has only very few sightings of his tail:

during landing the left spot in the centre of the tail was "divided" into two. that's because first two feathers with black on the tip were on top of each other. in the next frame the shorter top feather had moved slightly to the left and the black tip appeared to be a new spot.

It illustrates beautifully what I was describing here and why for myself I've reached the conclusion stated :

The two spots on the tail of this stranger are formed by bits of colour on different feathers. In addition, there are short white feathers partly overlaying the ones with the colour on them, so that the tail marks look quite thin on occasion (in a certain folding) and bigger when the feathers spread and the all white ones don't cover the colouring of the others anymore.
The safest way to compare tails, I think, is when they are in exactly the same folding and position. This is of course almost impossible, especially when a bird appears for only a few minutes or one or two short visits. Then it is helpful to draw in other features into the comparison, as feather patterns on the wings, the line above the eye, the whole gestalt.

Note: The pictures of my post then were those of Milda's tail - a confusion that was later cleared up.

[ame]

For sure Mr L is not Raimis? Sorry, I know it is an absurd question, but it is soo strange to me that Milda can change so quickly a partner. Sometimes I think that Raimis was not the first one for her, she seemed really experienced. And now I can say that she is very modern :) let's see what will happen, but she is really a very strong and special female!

rodjur, none of the males who have been here since Raimis disappeared is Raimis who has returned.
see pictures of the tails
Raimis and Milda:
https://www.looduskalender.ee/forum/vie ... 89#p797289
Mr C (Chips) and Mr L (Limpy)
https://www.looduskalender.ee/forum/vie ... 07#p797307
i haven't made a picture gallery of the other eagles yet.

[Ajeta]

I thought about Mr C and his behaviour with eggs and chicks a little bit more and found some interesting research on how hormones can apparently be influenced themselves by behaviour. I shall put some quotes here - context and more interesting reading to be found at the source (see below).

Quotes:
Social stimuli also modify gonadotropin secretion. Olfactory cues between female mice can interrupt normal estrous cycles and lead to pseudopregnancies or to periods of prolonged diestrus, termed the Lee-Boot effect; olfactory cues from male mice can shorten the estrous cycle and either cause rapid attainment of estrus, termed the Whitten effect, or terminate pregnancy in a newly impregnated mouse, termed the Bruce effect [3]. In male rhesus monkeys, sudden, decisive defeat by other males leads to prolonged reduction in plasma testosterone, which can be reversed in the defeated male by the introduction of a female companion [3]

Functional changes caused by hormones secreted in response to behavioral signals include modifications of behavior.

This analysis was taken further by Lehrman (see [1]), who showed that among doves the behavioral sequence of courtship, mating, nest building and parenting involves complex behavioral interplay between the partners that triggers further hormonal secretion,  which unfolds the next phase of behavior and hormonal secretion.

It is important to stress that hormones themselves do not cause behaviors; rather, hormones induce chemical changes in particular sets of neurons, making certain behavioral outcomes more likely as a result of the strengthening or weakening of particular neural pathways.

Source:
McEwen BS. Behavioral Control of Hormonal Secretion. In: Siegel GJ, Agranoff BW, Albers RW, et al., editors. Basic Neurochemistry: Molecular, Cellular and Medical Aspects. 6th edition. Philadelphia: Lippincott-Raven; 1999.
Available from: https://www.ncbi.nlm.nih.gov/books/NBK28047/

Thus I would not be surprised if the sounds of Milda and the chicks as well as other things specific to the breeding situation could work as just such triggers via the neural pathways (of these signals arriving and being processed in the brain etc.) At the same time, previous experience of the male with such circumstances may well help to trigger his responses.
It is really a vastly interesting subject and one cannot thank Mr C and those brave little chicks enough for making those observations possible.

[Ajeta]

Here's an abstract by Daniel S. Lehrman of, I believe, some relevance to what we saw happening with dear Mr C and the eggs / chicks in so far as it mentions several times the effect of external stimuli such as behaviour, sights and sounds on the relevant hormones. It is rather older, so research today should be even more advanced, but it gives an idea as to what factors could have played a role (source see below, passages highlighted by me):

Quote:
1Within the breeding seasons regulated by annual changes in environmental conditions, there exist detailed changes in the pattern of hormone secretion from stage to stage within the season, which are in part responsible for the successive changes in behaviour during the season.
2In many species of birds the general environmental variables induce greater development in the male reproductive system than in the female, so that males arriving at the breeding grounds in spring are usually more advanced toward full spermatogenesis than are the females toward ovulation. ...
3Stimuli arising from courtship behaviour induce the secretion of follicle-stimulating hormone by the pituitary gland of the female in many species of birds.
4The presence of nesting material and of the nest, and/or participation in nest-building behaviour, further contribute to the advancement of the reproductive cycle ...
5Stimuli provided by the eggs appear to be able to induce prolactin secretion, and to inhibit the secretion of FSH. The prolactin secretion so stimulated probably, in turn, contributes to the maintenance of incubation, and of the brood patch.
6Stimuli provided by the young are capable of inhibiting or delaying the onset of a new laying cycle, although the physiological basis of this is rather obscure.
7Recently discovered details of the physiological and anatomical relationships between the brain and the pituitary gland provide insight into the anatomical and physiological mechanisms by means of which external stimuli can reflexly cause changes in hormone secretion.
8The synchronization of the behaviour of the members of a mated pair, necessary for effective reproduction, is probably in part effected by the effects upon their endocrine glands of stimuli which they provide to each other, and which they receive from the eggs and young.
...
Source:
https://www.researchgate.net/publicatio ... i_in_birds

[rebelde]

I thought about Mr C and his behaviour with eggs and chicks a little bit more and found some interesting research on how hormones can apparently be influenced themselves by behaviour. I shall put some quotes here - context and more interesting reading to be found at the source (see below).
Quotes:
Social stimuli also modify gonadotropin secretion. Olfactory cues between female mice can interrupt normal estrous cycles and lead to pseudopregnancies or to periods of prolonged diestrus, termed the Lee-Boot effect; olfactory cues from male mice can shorten the estrous cycle and either cause rapid attainment of estrus, termed the Whitten effect, or terminate pregnancy in a newly impregnated mouse, termed the Bruce effect [3]. In male rhesus monkeys, sudden, decisive defeat by other males leads to prolonged reduction in plasma testosterone, which can be reversed in the defeated male by the introduction of a female companion [3]

Functional changes caused by hormones secreted in response to behavioral signals include modifications of behavior.

This analysis was taken further by Lehrman (see [1]), who showed that among doves the behavioral sequence of courtship, mating, nest building and parenting involves complex behavioral interplay between the partners that triggers further hormonal secretion,  which unfolds the next phase of behavior and hormonal secretion.

It is important to stress that hormones themselves do not cause behaviors; rather, hormones induce chemical changes in particular sets of neurons, making certain behavioral outcomes more likely as a result of the strengthening or weakening of particular neural pathways.

Source:
McEwen BS. Behavioral Control of Hormonal Secretion. In: Siegel GJ, Agranoff BW, Albers RW, et al., editors. Basic Neurochemistry: Molecular, Cellular and Medical Aspects. 6th edition. Philadelphia: Lippincott-Raven; 1999.
Available from: https://www.ncbi.nlm.nih.gov/books/NBK28047/

Thus I would not be surprised if the sounds of Milda and the chicks as well as other things specific to the breeding situation could work as just such triggers via the neural pathways (of these signals arriving and being processed in the brain etc.) At the same time, previous experience of the male with such circumstances may well help to trigger his responses.
It is really a vastly interesting subject and one cannot thank Mr C and those brave little chicks enough for making those observations possible.

Ajeta Thank you for bringing this up! As there seem to be no studies of similar developments in eagles to be found in the freely accessible research data, all we can do is use our eyes and ears plus any eye-witness material of similar cases. Sonchik's view appeals to me, though, because the development we saw taking place with our Golden Boy was fast (he was at some point seen as a super 'talented' eagle prodigy) , and on the other hand because it would better explain why he triumphed over our Silver Boy in the first place. So while another point of view can be plausible, there is no need to disprove the former.

I want to thank you for your long response to my long post from tuesday! After that there's been a parade of eagles' tails here in the discussion thread.

[sova]

Good afternoon to all
Ajeta, thank you very much for the effort
I like to read all of the discussions

[Ajeta]

Ajeta Thank you for bringing this up! As there seem to be no studies of similar developments in eagles to be found in the freely accessible research data, all we can do is use our eyes and ears plus any eye-witness material of similar cases. Sonchik's view appeals to me, though, because the development we saw taking place with our Golden Boy was fast (he was at some point seen as a super 'talented' eagle prodigy) , and on the other hand because it would better explain why he triumphed over our Silver Boy in the first place. So while another point of view can be plausible, there is no need to disprove the former.

I want to thank you for your long response to my long post from tuesday! After that there's been a parade of eagles' tails here in the discussion thread.

rebelde, you are such a dear! Thank you for taking an interest in those long cumbersome abstracts I posted today. As I wrote elsewhere Sonchik's hypothesis appealed to me, too, and the above research results do not refute it, I believe. One small problem I see may possibly be the time span in which Mr C would have had to change nests, so to speak. From my reading this morning I would also not underestimate the effect of trauma on his hormonal state, trauma e.g. by finding his partner dead on the nest or the chicks dead or gone or whatever may have happened. (Though that state again might have been reinduced by the presence of a new female, i.e. Milda.)
So it may well be possible - and would be really interesting to know, like e.g. if we knew that some territory perhaps not too far away had lost its pair of owners and the surviving male was Mr C. (You probably get what I am saying: We need cameras in every nest at least in Kurzeme ) It is as Sonchik said yesterday, we will never know. What I take away from my reading, however, is that it could very well have worked out with Mr C, Milda and Raimis' chicks if it had not been for another male so interested in this territory that he came back even after being defeated the first time round. Maybe Mr C was too merciful with Mr L for his own good. Myself I'm really torn between being happy to see Mr L back, and being very sad indeed that Mr C is not here any longer and that Raimis' last kids were not allowed to grow up under the kind care of there stepdaddy.

[Ajeta]

Good afternoon to all
Ajeta, thank you very much for the effort
I like to read all of the discussions

Thank you sova, that's very kind. Actually it was no effort - it was vastly fascinating reading all that stuff, though I'm no endocrinologist or anything. Well, perhaps there was some effort: Not to lump the thread with all I read, but to make a selection and cuttings But I'm glad you find it interesting.

[Ajeta]

rebelde, one afterthought, since you rightly pointed that out: I think the reason for there being rather little research on eagles with regard to the question of the interaction between external stimuli, neural pathways and hormones may be that it would be much more difficult to keep them in captivity. Somewhere I found, too, that captivity istelf can affect the hormonal state of birds and that research must really also go out in the field. Which of course is a lot more difficult. That's why I suppose these live cams are the best thing that happened for such kind of ornithological research, too. Of course, you cannot test the levels of hormons with them, but you can watch the eagles act very closely, and that allows at least some conclusion on their hormonal state, too.

[rebelde]

From my reading this morning I would also not underestimate the effect of trauma on his hormonal state, trauma e.g. by finding his partner dead on the nest or the chicks dead or gone or whatever may have happened. (Though that state again might have been reinduced by the presence of a new female, i.e. Milda.)

The idea that there would have been a straight forward movement from the Golden Boy's supposed loss to the new nest - with all the effort that it took - doesn't seem natural at all, and I don't believe that's what Sonchik hypothesized. There was definitely a development, and all that we saw the Golden Boy doing was an outcome of such development, which in turn was triggered by the circumstances and his assumed position as the guarding presence first in the territory and later in the nest itself.
The Silver Boy's behaviour is clearly different, certainly in part because there's no more clutch to form an opinion of, but in part possibly because of his different background. Somehow his appeal seems to be better synchronized with Milda's loss, now that the loss has been completed and Milda will have to live on.
Hormones certainly play their role in each of these different situations, and their production is certainly triggered by the same situations, when not vice versa.

[rebelde]

---these live cams are the best thing that happened for such kind of ornithological research, too. Of course, you cannot test the levels of hormons with them, but you can watch the eagles act very closely, and that allows at least some conclusion on their hormonal state, too.

Exactly.

I apologise for the off-topic issue, but have you noticed that Samuel Beckett would have made a beautiful male eagle? (I don't mind if these picture-links are removed from the thread as unfit for the topic, but I appreciate it if they are allowed to stay here as a curiosity.)
Here: https://www.uib.no/sites/w3.uib.no/file ... 1579194807

https://daily.jstor.org/wp-content/uplo ... 50x700.jpg

https://www.filepicker.io/api/file/yee0FUPSSEG8uC6vTguA

[Ajeta]

The idea that there would have been a straight forward movement from the Golden Boy's supposed loss to the new nest - with all the effort that it took - doesn't seem natural at all, and I don't believe that's what Sonchik hypothesized.
There was definitely a development, and all that we saw the Golden Boy doing was an outcome of such development, which in turn was triggered by the circumstances and his assumed position as the guarding presence first in the territory and later in the nest itself.

The Silver Boy's behaviour is clearly different, certainly in part because there's no more clutch to form an opinion of, but in part possibly because of his different background. Somehow his appeal seems to be better synchronized with Milda's loss, now that the loss has been completed and Milda will have to live on.
Hormones certainly play their role in each of these different situations, and their production is certainly triggered by the same situations, when not vice versa.

I was referring to this post by Sonchik:

Sometimes hormones are produced in stages, that is, in the order of the queue. Like the chain described by Maris: nest building - mating-egg laying - incubation.Without the first stage, the fifth stage will not turn on. They are dependent on each other. In this case, a lone eagle simply can not have hormones that provoke incubation. We need to delve into the literature to find out how this is actually the case.

With Moon Shadow I think the situation is really entirely different bc there is no clutch. Milda's and his relationship is not directed by the needs of young, but an ordinary courtship situation. They are respective owners of their halves of the territory (for the time being) and must somehow learn to relate. My impression is that Moon Shadow so far is slightly less willing to be bossed around than Raimis was. If so then perhaps either bc he's new or bc he is slightly bigger than Raimis. He also stayed on the nest yesterday long after she left. But I might be wrong. From the slightly darker impression of his plumage I would imagine him younger than Mr C. which presumably could entail a different level of experience. That might explain, too, why he still objects to being Mylady's dutiful servant, though he is polite, of course - he's after all smaller than Milda, even if on his first appearance on the nest he seemed almost double her size. (6th April ,17:20 ff)

I meant to ask you something else, as well: You said you used to post pictures and so on, too. What year was that?

[Ajeta]

I apologise for the off-topic issue, but have you noticed that Samuel Beckett would have made a beautiful male eagle? (I don't mind if these picture-links are removed from the thread as unfit for the topic, but I appreciate it if they are allowed to stay here as a curiosity.)

After copying those spectacular links (how did you come by them?) into my file of links by rebelde, where SB is now keeping company with Mr Spock, I shall reply:
Second only to Moon Shadow.

[rebelde]

I was referring to this post by Sonchik: ---

I meant to ask you something else, as well: You said you used to post pictures and so on, too. What year was that?

Aha. Ok. I read it quickly but didn't get back to it. (I'd better give up this talk of hormones and the Golden Boy's former life altogether... )
BTW who is Moonshadow?

As an answer to your question: I posted quite a lot of pictures to a thread of a biutiful Estonian WTE-nest of Suvi and Sulev with one girl eaglet, Sulvi, in the summer of 2018. It was a different period in my life and I was able to spend a lot of time doing it and making early morning observations of the nest. The nest was positioned so that the light was very nice most of the time, so there were a lot of photos in that thread, along with videos. It was only after the happier (but weaker by construction) estonian nests that I found the Durbe nest.