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Marsh Harrier behaviour
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Author:  Graham Catley [ Tue Jul 28, 2009 2:53 pm ]
Post subject:  Marsh Harrier behaviour
Watching a fledged family of Marsh Harriers the female produced food for two of the juveniles but as she was passing food to the second a 2cy Common Buzzard saw the first juvenile and made a low fast approach knocking the harrier from its perch and grabbing the prey; the female harrier then left the juvenile and started to dive bomb the buzzard dropping her legs and talons on each strike but the buzzard refused to move; after a few strikes all of the three juvenile harriers joined the female in her attacks with less vigour but the effect of multiple diving still had no effect on the buzzard and the harriers eventually gave up and left the mugger with its prize.

at a different site where there are four nests three had fledged young but one still had young in the nest. One brood had not received any prey deliveries all morning and the juveniles were clearly hungry and calling frequently. The adult male from the unfledged nest arrived from a great height and descended towards the nest in a stooping display eventually hanging over the reedbed; at this point one of the fledged juveniles from an adjacent nest flew at the male from behind and turned under him grabbing the prey and falling with the male into the reeds. The juvenile obviously held onto the prey as the male climbed up and started to dive bomb the juvenile screaming and dropping his legs but the juvenile again held onto the prey and after ten minutes it managed to sneak off low over the reed with the food leaving the male to go off on another hunt. I have sometimes suspected that juveniles from different broods take food from adjacent adults but this is the first occasion that I have been able to prove it as the young from the male's nest have still not fledged; maybe if they loose prey regularly that is why they are behind?
Author:  Alan Ball [ Wed Jul 29, 2009 8:38 am ]
Post subject:  Re: Marsh Harrier behaviour
I assume from this post, that you have already managed to eliminate the fact that the male could have been this fledged youngster's father? i.e. male paired with two or more adjacent females. If so, very interesting behaviour.

Alan
Author:  Terence Whalin [ Wed Jul 29, 2009 9:19 am ]
Post subject:  Re: Marsh Harrier behaviour
i also have witnessed a second male visiting a marsh harrier nest. I think it could be that in nature you always know your mother but the rest is conjecture, with a raised eyebrow or two.
This year myself and 2 birding mates from derbyshire visited leakenheath rspb, we have been visiting the area for the last 30 years or so and we are sure we saw a 3rd bird helping to feed the young at a golden oriole site. We have never witnessed this species doing this before but when you see an absolute cracking male then a female and another that looked like neither in so much that females as they age develop a much brighter plumage than younger birds. We all looked at each other, did you see that was the common thread, possibly one of last years young, a second female possibly, 2 females 1 male feeding young at the same nest. has a second female layed in the same nest ? all these items discussed and none of them ruled out. I have heard of this type of thing with hornbills apostlebirds etc and i think this is a more frequent occurance in nature than we think because we do not generally look for it and only notice when it is glaringly obviously a third bird.

terry whalin :wink: :D
Author:  Stuart Britton [ Wed Jul 29, 2009 2:37 pm ]
Post subject:  Re: Marsh Harrier behaviour
There was a study in Sheffield in the mid-90's by Ben Hatchwell that found that unsuccessful breeding Long-tailed Tits helped to feed and raise successful broods belonging to their siblings. This was done by colour ringing and close observation. A later study using DNA profiling showed that there was evidence of polygamy by both males and females of the species. We still have a lot to learn and unique marking of individuals (colour ringing/wing tags etc.) and DNA can prove what can only be conjecture in the field.
Author:  Malcolm Johnson [ Thu Jul 30, 2009 9:31 am ]
Post subject:  Re: Marsh Harrier behaviour
Hi
I have on my property a nest of swallows that return year on year. I have noted that over the past three years they have brought off two broods. The first is two and the second is four or five. I am fairly certain that the two first brood are roped in to help feed the second, as there is often a train of three coming and going with food.

Malcolm.
Author:  Graham Catley [ Thu Jul 30, 2009 1:01 pm ]
Post subject:  Re: Marsh Harrier behaviour
Alan Ball wrote:
I assume from this post, that you have already managed to eliminate the fact that the male could have been this fledged youngster's father? i.e. male paired with two or more adjacent females. If so, very interesting behaviour.

Alan


Yes different males with notable differences in plumage; as the nests were so close together there was frequent aggression between the males and also the females; as this male went into some display on its descent I wondered if the other male was in fact perched somewhere nearby but out of sight but he never appeared so maybe the display was triggered by the presence of the screaming young from the other brood.

Interestingly there have been two fledged juvenile Peregrines at Alkborough for the last week; two nights back a reliable observer saw an adult Peregrine come in with prey and take it to one of the youngsters; I am not sure how far the nearest nest is but it must be in excess of 5km and as the young have effectively fledged this seems a very odd bit of behaviour.
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