Estonian Osprey Nests Ilmar & Irma ~ DISCUSSION~ 2014

[WickedRed]

Oh my........ Beautiful renditions, Kertugal ! Something to tide us over !

[lianaliesma]

thankyou, Kertugal/ Sophie!

[Kertugal]

A beautiful drawing of the chicks, you have succeeded to capture their exciting expressions so naturally, thankyou, Kertugal!
Is it a harsh Aino on the nest and a milder Elar arriving that time?

Thank you Owlie and every body . It is the first fledge of Aino
Send you this one: the Ilmar's familly: Ilmar comes with a fish, Irma is beetwin Aino and Elar

[Birdfriend]

It is a beautiful drawing from our osprey family! Amazing moments from their Nest-Life. Thank you!

[Summi]

Thank you to Urmas and all the Forum members and also Site Admin and Bea as moderator.
Thank you to Kertugal/Sophie for your amazing design - one may identify every osprey by recognizing the characterisitic look you have put into each of them and what is more - the misty morning background makes it all alive and real.

[Alex10100]

Good luck to the young ospreys, we would like them to be with us forever, but this is nature and this is the way it is

[Joanna]

Can anybody tell me, how many miles per hour ospreys normally fly , I mean what time the journey will take?
So that one can tell whereabout our youngsters could now be ...

I count every day until spring time, when they will be back - at least Ilmar and Irma

[Bea]

Joanna, here in this topic about the Rutland Ospreys you can find very detailed information about their migrating Ospreys, like flight altitudes, how many kilometers a day with which speed, roosting places and much more ...

viewtopic.php?p=342507#p342507

They take different routes, of course, but it is good to get an idea about their daily trips and all around it.

[Kukelke]

Can anybody tell me, how many miles per hour ospreys normally fly , I mean what time the journey will take?
So that one can tell whereabout our youngsters could now be ...

Average speed of an osprey is about 35 km/h.

The fastest ospreys are recorded to use 11 days to get to Africa (from the UK to Senegal), the slower ones can use a full month, sometimes even more.
It depends on the individual bird, on the weather during the journey, if an osprey flies non-stop and only roosts during the night or if an osprey decides to stage on certain points along the route, etc.

If I had to make a qualified guess, I would say that Aino could have reached the north coast of the Black Sea by now, somewhere between the Crimea in the east and the Donau delta in the west, while Elar and Ilmar could be a bit further north, between Kiev in the east and Krakow in the west.
Alternatively, Aino could have taken a more westernly course and then be somewhere in Hungary or Croatia, but most ospreys from Finland and the Baltic countries take the route via the Black Sea to Turkey and then further down into Africa.

My guess: Aino in the red area somewhere, and Elar and Ilmar in the green area:

[Owlie]

When you look at the previous years migration routes of various birds from Estonia/Latvia on the migration map, you can see that many of them choose the route via Bosphorus ("İstanbul Boğaz"). My mother having served at a radar control will remember that this phenomenon is widely known ... What is the specific reason for the birds to fly through Bosphorus especially - in between the Black Sea and the Mediterranean Sea ... ?

[Kukelke]

When you look at the previous years migration routes of various birds from Estonia/Latvia on the migration map, you can see that many of them choose the route via Bosphorus ("İstanbul Boğaz"). My mother having served at a radar control will remember that this phenomenon is widely known ... What is the specific reason for the birds to fly through Bosphorus especially - in between the Black Sea and the Mediterranian Sea ... ?

The same reason why many birds fly for example across the Strait of Gibraltar or via Falsterbo in South-Sweden to Denmark or North-Germany: they don't like to fly over vast open waters but prefer to stay over land as much as possible. Many bird species then continue over land to Africa, via Syria and Israël to Egypt and further down.

Ospreys are actually one of the exceptions; they don't care much if they have to fly long distances over open water. The fact that many Estonian and Latvian ospreys cross near the Bosporus has rather to do with the fact that it just happens to be on their path; after all the shortest route between Estonia/Latvia and their wintering grounds in Africa is straight south via the Bosporus.

[Owlie]

So simple mathematics - when you understand it in the entirety - thanks again for helping 'us without maths know-how', Kukelke!

[NancyM]

Many thanks to Bea, who organized all the fish information including photographs and videos of each delivery ( ) and to everyone who documented fish arrivals (and departures). After a great delay, I finally put the 2013 data into a spreadsheet and also the new data from 2014.

Ilmar is a fish delivery machine! In 2013, he delivered 726 fish (or pieces, after he had eaten a bit) - that year there were three chicks in July and of course, sadly, only two chicks in August. This year (2014), even with the cam offline for 19 days in June, he delivered 832 for two chicks. No wonder there was no terrible competition - they both had plenty to eat.

I have sent the spreadsheets to Urmas and Bea, and I will post a couple of summary charts here.


...

[Kukelke]

Thanks NancyM & Bea

Neither last year nor this year the chicks were starving. There was always plenty of food for them.

The statistics clearly show that the fish brought to the nest in July and August, and partially also in September this year were on average smaller than the fish brought to the nest last year - which we observers knew already. I got the impression that last year the fish varied more, both in size and in species than this year.
In contrast to last year, this year we saw that the bulk of the fish delivered by Ilmar in that period was small carp of around 100 gr in weight, which must have come from a nearby fishfarm.

After all, in fish farms they tend to keep fish of the same age and size in the same pond, and only fish which is commercially of interest like carp and trout. From own experience I know that young, small fish stay very tight in the water of such a pond, often so much that there's as much fish as water in such a pond. Again this corresponds to the intervals at which Ilmar delivered his fish: 3 of these small fish delivered in the course of 15-20 minutes were no exception, so fishing must have been very easy for him.

The difference in numbers in April of both years (9 vs 51) can easily be explained because Ilmar was here 4 days earlier this year on one hand, and on the other hand this other female osprey (the Dark Beauty) tried to make the nest her home, and Ilmar had to fish for her too for almost a week. (Actually Ilmar was earlier on the nest last year, but first he needed some days to get rid of the pair of White Tailed Eagles who tried to occupy his nest)

[Birdfriend]

Thank you very much,Kukelke,Bea and Nancy M.!
Very interesting informations about Ilmar the great fisher and over the flightroutes our ospreys.
Think you,Kukelke,that Ilmar and Elar together or alone take the same way for their migration?

[NancyM]

There is a lot more to be mined from the fish data, including the numbers of each species as identified by the observers (mainly Bea). I think you are right that there was more variety last year, Kukelke. I think the shortest interval between fish deliveries was something like 2 or 3 minutes - clearly, that fish farm is very close! On at least two occasions, he delivered two small fish at once.

Unfortunately, numbers by themselves do not document size (the pictures and videos are needed for that). But if Ilmar is fishing at the same farm, why would he have smaller fish this year than last? Did something change in the way the operators of the farm stocked the ponds? There are always more questions ...

[Kukelke]

Very interesting informations about Ilmar the great fisher and over the flightroutes our ospreys.
Think you,Kukelke,that Ilmar and Elar together or alone take the same way for their migration?

Ospreys migrate alone, never in family groups. Even if they leave the same day, each will take different paths.

Osprey migration is still not completely understood by scientists, but evidence from tracked birds suggests that adult birds use more or less the same route every year.
However, "route" should be understood as a broad corridor rather than a fixed highway with road signs. Influenced by local weather and wind conditions during passage, visibility, natural obstacles like mountain chains etc, an adult osprey can fly up to some 500 km east or west from the route taken previously (hence the broad corridor), although they seem to return to certain staging points along the route, where they know there's food available, so they can 'fill their tanks' and rest before continuing their journey.

For juvenile ospreys, migration is different. They have noone to show them the way. All they have is an instinct to migrate at the end of summer, but they don't know where they're going or what the goal at the end of their journey is. When their instinct to migrate becomes strong enough, they just start to fly into the most plausible direction, which normally is south. One could say that juvenile ospreys begin on a new migration every day, until they reach an area which they 'like', where there's enough fish, warm temperatures and things like that (for some ospreys this is the Mediterranean coast of Southern Europe, while other ospreys continue deep into Africa).

This 'not having an imprinted route yet' also explains why juvenile ospreys in particular on their first autumn migration often fly over vast stretches of seas and oceans, much more than adult birds tend to do. First when these juvenile ospreys return, normally at 2 years old (sometimes at 3 years old, and very rare, at 1 year old), they find out that there are safer ways over land with much less vast stretches of water to cross, and once an osprey has discovered such a route (or corridor as mentioned above), it will stick to it for all other migrations to come.

The above is especially true for European ospreys who take the western route (birds from the UK, Germany and western parts of Scandinavia), and also for east coast ospreys of North America.

Just to illustrate this, here an example of a North American first time migrator (and record holder):


He left home around 10:00 on the 8th, flying SSE. He flew non-stop for about 66 hours, covering just over 1,550 miles (2,500 km).

Note that not all juvenile ospreys in N-America do this. Many follow a route over land and cross the water at a later point. Again, this has probably to do with local weather conditions and things like that at the day of departure.
On their way back, these ospreys can see the islands and landmasses from the sky, and then follow these via Cuba and the Bahamas to Florida and further north over land.

[Kukelke]

Unfortunately, numbers by themselves do not document size (the pictures and videos are needed for that). But if Ilmar is fishing at the same farm, why would he have smaller fish this year than last? Did something change in the way the operators of the farm stocked the ponds? There are always more questions ...

Fish farms tend to be divided into smaller units, with fish of the same year in the same pond. Once the fish in a given pond reaches marked size, it will be harvested. So it's possible that the fish in the fish farm pond where Ilmar was fishing last year, was harvested and replaced by small fish this year. Or the actual pond with bigger fish (which represents a much higher value for the owner) was covered by plastic sheets or nets this year, so Ilmar wouldn't have access to it and instead went after the smaller fish from a nearby hatchery pond which was still accessible for him.

[Bea]

When I remember right, owners of commercial fishponds in Estonia can make application for financial compensation from the government, when they can prove, that Ospreys or White tailed Eagles are fishing regularly in their ponds.
It was also said, that the amount of compensation is fair.

I think financial compensation is also a way to avoid fishfarmers using these dangerous nets over ponds. They are life-endangering for raptors, as well as for White and Black Storks, Herons and more!

Fortunately I never saw nets over ponds until now in Estonia.

High-value fish might be kept in ponds closer to human settlements/houses/villages, so that raptors will not easily access them.
As far as I know Trouts (one of the more expensive fishes) need very oxygen-rich water which flows permanently, so electricity and pumps are needed and so won´t be kept in ponds/basins far out.

[Birdfriend]

Thank you very much,Kukelke, for the fully documentation and information! You are a great osprey specialist!