Goshawk feather remains: detectives needed (1 Viewer)

I recently (29 July) found some feather remains of an almost fully fledged Goshawk Accipiter gentilis (thanks to Peter Sunesen for confirming the ID). Some feathers show distinctive damage and I wonder if it is feasible to reconstruct what might have befallen the youngster.

The remains were found on the woodland floor about 15 metres downslope from the nest tree. There were two bunches of wing feathers, and several smaller individual feathers within the same area, but certainly not a complete set of flight feathers, no scattering of body feathers, and no tail, body or legs. The biggest of the two bunches is shown in situ in the first (left) image, and isolated in the second image. It consisted of much of the hand of the left wing.

There are several trees and patches of ground cover between the nest tree and the tree nearest to the remains, and the remains were found on the downslope side of the latter, within a relatively flat area about one metre in diameter immediately behind the trunk . So, it seems unlikely that the fledgling died or was killed and then dismembered in the nest, because the feathers could not have found their own way to where I found them. Either something took the fledgling from the nest, or it fell from the nest and was grounded. Presumably it must then have died or been killed, and any substantial remains could have been taken by scavengers. Is that a reasonable conclusion? Mammalian predators/scavengers in the woods certainly include Beech Marten Martes foina and Fox Vulpes vulpes. The second image shows at top right a distal section of feather that has broken or been removed from the basal section.

Some feathers look as if the barbs have been neatly snipped off, at a rather consistent angle (red lines in image 3 indicate some of these). Does this look familiar to anyone? Is it likely that a raptor has caused this damage with its beak? I wondered if this damage could suggest that a raptor took the fledgling from the nest, killed it on the ground nearby, and took the body with it. Perhaps a more advanced sibling was responsible, or an unrelated Goshawk? There are (allegedly) Eagle Owl Bubo bubo in the region but I have not seen or heard one here. Or might this damage have been inflicted previously while still in the nest?

Finally, the right-most image shows the ventral side of the partial hand. It shows that the outermost primaries are still in the process of emerging from the basal sheath and show more or less wavy edges that seem to reflect the helical growth pattern within the sheath. Would anyone with experience of young Goshawk in the hand be able to suggest probable time since hatching, and/or time until flight?

Thanks for any thoughts.
Brian

Hi Brian,

Thanks for the PM to alert me to this "mystery".

Except for photo three everything looks pretty normal if a Fox had found the dead (or alive) young on the ground and chewed off the wing tips (hand) and some feathers by biting off bones and indivial feather shafts.

Raptors/owls pluck off feathers leaving the shaft intact in their full lenght, and they are not able to sever the outer wing (hand) as shown here.

The third photo shows large missing parts of the inner and outer webs, and this is not at all typical when examining remains from plucking sites for raptors.

Even if playfull young foxes had fought over the wing in question (thus biting and damaging the webs of the feathers) I'm quite sceptical that the damages would at the same time leave the shafts of the feathers as intact as seen here.
My best guess would be that these 'soft' parts of the feathers have been eaten/bitten off by insects. Larvae of Dermestidae beetles actually eat feathers resulting in similar damage.

The fact that a few feather shafts are broken/cut off, could lend credit to the theory that the bird was shot on/near the nest with a shotgun, but to be certain one should look for signs that individual pellets/shots had gone through the wing, leaving underlying feathers (on the folded wing) damaged in the place one would expect.

However, there is no way that shots alone could result in the damages of the soft parts of the feathers shown in the third photo, but if this wing was soiled by blood (perhaps caused by a gunshot having broken the wing on the still live bird), insects (wasps?) may have chewed off the soiled parts of the feathers to get full use of the nutriants....

I know perfectly well that this is mostly hypothetical, but it's my best shot, so to speak

Peter

Hi Peter,
Many thanks for your reply. Very useful, and I have certainly learned a few things. I had not appreciated that broken feather shafts suggest mammal involvement, nor that raptors invariably pluck feathers entire. Interesting also that what looked like the effects of a raptor's beak (3rd image) is nothing of the kind. Guess I will never know what actually happened to the young Goshawk, but the simplest hypothesis - based on your interpretations - is that it left the nest prematurely, perhaps blown off during one of the gales that periodically sweep the hillside, was grounded, and was killed and/or scavenged by a fox. The rest of the bird is presumably inside a fox somewhere so cannot be checked for signs of shotgun use. Damned unfortunate for the bird, but I am consoled by the knowledge there are two or more juveniles still in the vicinity, alive and fit and calling periodically for food!
Best regards,
Brian

Biancone said:

Hi Peter,
Many thanks for your reply. Very useful, and I have certainly learned a few things. I had not appreciated that broken feather shafts suggest mammal involvement, nor that raptors invariably pluck feathers entire. Interesting also that what looked like the effects of a raptor's beak (3rd image) is nothing of the kind. Guess I will never know what actually happened to the young Goshawk, but the simplest hypothesis - based on your interpretations - is that it left the nest prematurely, perhaps blown off during one of the gales that periodically sweep the hillside, was grounded, and was killed and/or scavenged by a fox. The rest of the bird is presumably inside a fox somewhere so cannot be checked for signs of shotgun use. Damned unfortunate for the bird, but I am consoled by the knowledge there are two or more juveniles still in the vicinity, alive and fit and calling periodically for food!
Best regards,
Brian

Click to expand...

Good to hear!

Goshawks are particular favourite birds for me, and this year I found the first breeding 'urban-Gos' for Denmark in a very dog-and people crowded park near Copenhagen.
The beginning of the breeding season offered splendid, prolonged, close range views of these two very confiding indivials. Both were first time breeders (2 cy. female in juvenile plumage, and 3.cy male in first adult plumage) ending succesfully with two fledged youngsters, right now still begging for food hidden in the canopy, but soon to be independent and free roaming:t:

Peter

That's also good to hear. Also one of my two top birds. I've never seen any of the urban breeders though, and certainly never had "splendid, prolonged, close range views..." of any Goshawk!
Brian