[Tweeters] Bald Eagle peep show....(long)

Sammy Catiis Hikersammy at msn.com
Wed Mar 9 21:46:06 PST 2016

Yes, this is true. I have witnessed on several occasions on Fir Island, what I can only assume to be the parents, very much moving aside as soon as they see the 1st year arriving. They don't wait, and I have watched them keep others away while they eat. It is an interesting behavior and one I have on video somewhere in my old records. Hopefully not part of what was lost in several computer fails.

The Lake Casitas from last year is correct. What happened, and we know this, as all the eagles were tagged. One of the females from the Channel Islands, flew 100 miles to Lake Casitas. Landed on the nest, and killed the young in the nest, then proceeded to kill the Female parent. She was never found, and assumed dead. THEN she took up with the Male and copulated and they were successful in a new set of offspring. So, not the fairy tail you want to hear. The sad thing is, this couple on the lake have been very much documented. Many people have written on this couple, and I think even a book or two. What would possess a Female to fly that far and do this, I don't know. But you have to wonder what the Male was thinking.. "sleeping with the enemy" comes to mind.. haha But I suppose that instinct is the strongest emotion.

I will have to look for the photos of the 1st year in the nest with the young and parents in Snohomish. I know I took photos.. I'm not sure where they are at.

Interesting life of birds to be sure..



From: Martin Muller <martinmuller at msn.com>
Sent: Wednesday, March 9, 2016 9:34 PM
To: Sammy Catiis
Cc: tweeters at u.washington.edu
Subject: Re: [Tweeters] Bald Eagle peep show....(long)


Your observations are very interesting. The observation of an immature bird helping feed young is worth writing up and having published.

Here’s what the Birds of North American (online) says on the subject:

"Cooperative Breeding

On Amchitka I., AK, 2 different nests had 3 adults in attendance in 2 separate years, and 3 adults were reported at 3 nests in 1 yr (Sherrod et al. 1976<http://bna.birds.cornell.edu/bna/species/506/articles/species/506/biblio/bib260>). Fraser et al. (1983<http://bna.birds.cornell.edu/bna/species/506/articles/species/506/biblio/bib106>) reported 3 adults at the same nest in Minnesota over a 3-yr period. Sex of third individual unknown. In Connecticut, extra male delivered food to nestlings but generally avoided interactions with pair (Hopkins et al. 1993<http://bna.birds.cornell.edu/bna/species/506/articles/species/506/biblio/bib169>). In California, extra female assisted with incubation and food provisioning of young; was tolerated by pair. Low numbers of adult males may have provided incentive to female for cooperative venture (Garcelon et al. 1995<http://bna.birds.cornell.edu/bna/species/506/articles/species/506/biblio/bib110>)."

Source: Buehler, David A. 2000. Bald Eagle (Haliaeetus leucocephalus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/506


I did a quick check of Stalmaster’s The Bald Eagle (Universe Books, New York, 1987) but did not find any mention of cooperative breeding. I don’t have my copy of Gerard and Bortolotti (Gerrard, J. M. and G. R. Bortolotti. 1988. The Bald Eagle: haunts and habits of a wilderness monarch. Smithsonian Inst. Press, Washington, D.C.) handy, but it would be good to check that out on the subject too.

Does anyone in Tweeter-land know of any reports of this?

As to your almost certainty that it’s “the kids” coming back in following years. How do you determine that? Are they tagged or otherwise marked?

We’ve been studying Peregrine Falcons in Seattle and banding their young. We’ve seen youngsters food begging in late-winter (when they are supposed to be independent), and in one instance the adult male actually fed the food-begging immature female. However, that female was un-banded while we put bands on all of his offspring. So even receiving food from an adult is no guarantee of kinship (and I’m extrapolating from peregrines to Bald Eagles here).

I’ve seen winter battles over food with immature birds making some pretty serious-looking attempts at stealing food from adults (or other immatures), which, had the adult not relinquished the food might well have resulted in the adult getting injured. I’ve never seen an adult give up food to an immature without a fight. Were you referring to adults passively relinquishing food to immatures or were you also referring to immatures threatening adult and taking the food by force?

For all I know the longer feathers on young bald eagles not only give them an advantage soaring, it also makes them more imposing so that during battles over food they get to win occasionally, to make up for their lack in skill to procure enough food for themselves during this high-mortality stage of their lives.

I did a quick check on the Lake Casitas eagles (which I was not familiar with). Found a 2015 report about an adult female wounded during territorial battle (with pretty gruesome picture), but it was only a partial report. I didn’t feel like signing up to read the rest. Maybe you can summarize?

Martin Muller, Seattle
martinmuller at msn.com<mailto:martinmuller at msn.com>

On Mar 8, 2016, at 11:25 PM, Sammy Catiis <Hikersammy at msn.com<mailto:Hikersammy at msn.com>> wrote:

Just as a note of possible interest, I've witnessed almost certainly the kids coming back to the nest the next year. Sometimes landing IN the nest.. and sometimes even being still fed by the parent. Or more like supplemented. There is one instance where I seen that the kid actually stuck around and helped feed his new hatched brothers and sisters.. I've only seen that one time in a nest in Snohomish, but I'm sure it happens more than we realize. When it comes to Eagles, there is no certainty is there. They don't mate for life always and may even step out of the relationship when given a whole lot of eagles in an area . I think for some areas, we are just more used to there being less eagles & more competition which keeps the kids away from returning and more battles for nesting areas. Just my two cents.. :D I have watched many parents during the Winter keep other Eagles away from a catch and call and call, just to move aside for a 1st year, which I can only assume is theirs. In most observances, the young come back to the area just to be chased away from the nest. Tough Love I suppose. If you don't know of the Lake Casitas story last year.. it may be of interest.



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