Karl II and Kaia already have long periods of absence from the nest at the beginning of 2020 and in the following 2 seasons.
For example, Karl II had incubated a full 24 hours from May 25th to 26th.
But Kaia had also incubated for over 18 hours in this season.
It's not that long every day, but a change of parents normally only takes place once in 24 hours in this nest and sometimes no change at all.
We don't know exactly why the parents often have such long absences. Drought can be a reason and long search for food.
It takes time to determine the exact mean incubation period.
asteria wrote: May 27th, 2023, 4:38 pm
Karl II was swearing on the ravens. Never heard such sounds from any stork.
Thank you for posting the strange conversation; I thought at first it must be the raven. But then I began to look at Karl's beak and it does seem that he was the one making the sounds. I've never heard such sounds either.
tsang6482 wrote: May 27th, 2023, 11:46 pm
It seems as though there have been quite a few attempts by goshawk, ravens etc in this nest this year, as compared to others.
Is that really the case, or there just better documentation of it here?
There are far fewer Goshawk attacks here compared to other nests. the harassment by ravens is also rather low.
I can assure you, at other nests, ravens were sit at the nest tree for over an hour and came several times a day.
EDIT:
BTW: Ravens do not come to an occupied nest to steal eggs. they come to bully. And not only ravens have this behavior.
Mobbing response:
The mean response evoked by particular predators differed. The most highly mobbed species was raven, followed by hooded crow ....
Hello @tsang6482
I am glad that the ravens have not been so intrusive so far. So far, the ravens have only taken a short time of Nuisance.
A hawk has not yet been shown this season. The owl was noticeable for this.
Swenja, many thanks for your continues observations, wonderful pictures and videos.
And also thanks to everyone for your valuable contributions!
Swenja wrote: May 28th, 2023, 7:54 am
07:20 A raven above the nest. Kaia hisses and defends.
Oh, those ravens!
I don't know much about the behaviour of ravens, but I do read that they are egg thieves, and that they also devour chicks, and - if not too big - the parent birds are sometimes also on the menu.
… One of the things that makes the common raven so successful is that it is an omnivore and will eat just about anything that agrees with its digestive system. This includes both plant and animal material. They hunt small rodents, reptiles, amphibians, arthropods, and insects. They eat grain, fruit, and berries and can be pests to farmers. They scavenge and will not only eat carrion but the insects and insect larvae that are drawn to carrion.
They enthusiastically eat roadkill, and human garbage and will pick out the undigested food in feces. They raid the food caches of both ravens and other animals and hide that food in their own food caches. Common ravens eat the eggs and young of other birds and if the bird is small enough, it will eat the adult as well.
Ravens have been known to kill and eat newly born lambs, goats, and calves and don’t care if the animal is endangered. If a young raven finds a large carcass being enjoyed by adult ravens, it will call its friends to the food source. … https://a-z-animals.com/animals/common-raven/
VIDEO Raven the Egg Thief - Part 2: Searching, Stealing and Hiding
The intentions of the ravens (which we see here in Karula) are anyone's guess.
Usually, predators and birds of prey are the ones being mobbed. The BS is not a raptor.
In any case, it is clear that Karl II and Kaia react very defensively to their presence.
Mobbing: What It Is, and Why Do Mobbed Birds Put Up With It
Whether you are a bird watcher or not, you have probably seen a larger bird being harassed by one or more smaller birds. This behavior is called “mobbing” and you may be wondering why the larger bird doesn’t defend itself. You are not alone.
Many species will swoop and chase flying or perched birds larger than themselves, sometimes even striking them. Birds as small as sparrows, along with larger birds such as crows and ravens, may actively mob raptors. At times, even raptors may exhibit this behaviour, as in the case of the Peregrine Falcon in the photo above. The attacking bird typically does this in an attempt to drive away birds, and sometimes mammals, that they perceive as dangerous. Mobbing can happen any time of the year, but is especially common in the spring and early summer – the breeding season. The “mobbing” birds will be actively defending themselves, their breeding territory, and any nest with eggs or chicks. At times, however, birds may even defend a non-breeding home range. This may be an effort to protect themselves, as well as their food source. … https://centerofthewest.org/2019/01/21/ ... hemselves/
Edit:
I have repeatedly seen my cat being mobbed by blackbirds if she got too close to the bush where the blackbirds had their nest. Impressive aer-attacks, which somewhat unnerved the cat.
And I have also regularly watched a little gang of crows perform mock attacks on flying buzzards.
“Clearly, animals know more than we think, and think a great deal more than we know.”
— Irene Pepperberg
Swenja wrote: May 27th, 2023, 11:57 pm
Karl II and Kaia already have long periods of absence from the nest at the beginning of 2020 and in the following 2 seasons.
For example, Karl II had incubated a full 24 hours from May 25th to 26th.
But Kaia had also incubated for over 18 hours in this season.
It's not that long every day, but a change of parents normally only takes place once in 24 hours in this nest and sometimes no change at all.
We don't know exactly why the parents often have such long absences. Drought can be a reason and long search for food.
It takes time to determine the exact mean incubation period.
Volunteers step forward please!
Yes, Swenja, on this nest it is quite common to see long incubation shifts.
Shifts of 12-15 hours are the norm rather than the exception.
It's not always this long, but it's often. (And often Karl II incubates more hours a day than Kaia)
And if the birds want to switch shifts, a very long (21 to 24-hours) shift is not exceptional either.
Broadly speaking, I think it can (almost) be concluded that someone does the night shift and someone does the day shift. The one on night shift looks for his food during the day. The one on day shift seeks his food in the (early) morning and in the evening.
I don't know if these long shifts have to do with food scarcity, or if this "routine" just suits our birds well.
I am willing, if it would be useful, to list the duty hours of the past few years. But that would indeed be a huge job, and it cannot be done immediately.
“Clearly, animals know more than we think, and think a great deal more than we know.”
— Irene Pepperberg
Hello @Anne7 you are welcome!
Thank you for the very nice contribution and the video about ravens.
I have already scribbled down the dates from the laying of the 4th egg this year. I would just have to sort them and write them down in an overview. When calculating the mean value, however, I might have to round off, as there are times when the camera transmission is interrupted and the parents change. Unfortunately, that doesn't make it exact.
And it will still take time, even if I have the scribbled data here.
Swenja wrote: May 28th, 2023, 2:08 pm I have already scribbled down the dates from the laying of the 4th egg this year. I would just have to sort them and write them down in an overview. When calculating the mean value, however, I might have to round off, as there are times when the camera transmission is interrupted and the parents change. Unfortunately, that doesn't make it exact.
And it will still take time, even if I have the scribbled data here.
Hi Swenja
I think there is no problem in rounding up the duty hours. For ease of calculation, I would even round up to the nearest hour and half-hour. Especially since hours/minutes are not decimal. So, for example: 1 hour, 1.5 hours, 2 hours, 2.5 hours etc... Rounding, sometimes up, and other times down, tends to minimise the error margin in the final result. In the final result, the error margin will not exceed 15 minutes. And a quarter of an hour is only 1/96th part of a 24-hour period. That’s 1.04167 %.
“Clearly, animals know more than we think, and think a great deal more than we know.”
— Irene Pepperberg
