I became interested in what Linda and Sulev on the WTE nest camera brought for their chicks: what kinds of fish, and how much else. In winter WTEs seemed quite happy to eat meat. Of course the results here may reflect our posts, screencaps and interests as much or more than the eagle family's real diet.
This was 2009. How much different is it this year?
In 2009 (March – mid-July) there were birds on 13 occasions, ”some animal” 2 times, otherwise fish, whole or in pieces, according to posts and screencaps. The fish were not often identified, but pike was most often mentioned, also perch.
Backgound & details
I have checked last year’s discussion, but by far not as carefully as Ame did for her research. I haven’t checked any Pontu images (if they are available at all any longer), and not looked at this year’s records.
Camera went on-line in the beginning of March (March 4, 2009). Eggs were laid on March 12 and 14. Sulev brought food for Linda while she was incubating the eggs, but she also went fishing for herself. Chicks were hatched on April 19. Camera was running until October 7, but after mid-July nest was often empty and eaglets even spent the night elsewhere, and feeding was only occasionally mentioned in posts.
During the feeding period with eaglets in the nest, April 19 to around July 15, there were 12 reports of birds brought in for food, mostly in the later half of the period: 8 reports June 15 – July 15. Probably half of them or more were cygnets. Urmas explains in a post on June 20, 2009 that they probably were mute swan chicks.
Sulev also brought a bird (a crow?) for Linda on April 11.
”Meat” – not fish or bird – was mentioned twice: April 2 (rabbit?) and something unidentified with 4 legs on May 2.
The fish that were brought to the nest are mostly not identified in posts, just ”fish”. Pike, bream, perch were named. Pike was also identified in a video (April 15). Ruff, or some kind of "dotted" fish was discussed (May 4). According to information from Looduskalende (posted by Yarko, May 5, 2009) , pike and pikeperch would be the expected prey in the sea in this area.
On my laptop screen few of the fish in the screencaps seem easy to recognise. It might be better with a larger screen, and of course with first-hand knowledge of the fish species that are common there.
In literature it is said that WTEs generally divide the prey into pieces before bringing it to the nest. In the forum posts whole fish (”huge fish”, ”a large fish”, ”a fish”) is quite often mentioned.
Both fish and birds were seen to be brought in alive occasionally (3-5 times). Actually the last bird, a black and white one, may have escaped. The screencap (July 13, 2009) shows it sitting on a branch beside the nest.
The interest in the forum was more on the feeding of the eaglets, and not so much on what was brought; the preys may be better identifiable with slightly different screencaps. I have not compared this year’s screencaps to see if the current camera position is better for prey identification.
Mutikluti who has been watching the cameras most carefully of us all and who is not so very far from the eagle region, probably knows much more already.
How many times food was brought in was discussed twice at least. On April 21, 2009 it is mentioned that the chicks are fed nearly every hour, later (May 8) it was noted that there were at least 6-7 feedings a day, but that some feedings went on for a long time. I have just looked for ”major” feeding events with possibly identifiable prey in posts, not tried to count or analyse all posts that mention feeding. There is a very large uncertainty and distorting factor anyway: how many feeding occasions were not noticed or mentioned at all?
On the whole it looks as if the eagles’ fish diet was rather more varied than only pike and pikeperch. So it should be interesting to try to identify the species more often, to see for instance if there are changes with the season, or with the growing up of the chicks, or in years. Asteria? (June 10, 2009) suggested that Sulev brought smaller fish to encourage chicks to eat by themselves, and large ones to feed them.