The 'Honey-buzzard' that was a Goshawk

The breeding male Goshawk, 30.v.2016

Friday 10 June, forecast "sereno" (sunshine and cloudless sky) from dawn to dusk.  Hah!  Yea, right.  Well, only a few spots of rain, but chill breezes, and clouds clustering dark and heavy right over the valley. Then, it abruptly cleared to blue sky and hot sun around mid-afternoon, by which time I was on my way back down.

It was a strange session.  After about an hour I saw a raptor moving across the head of the side valley where the male Goshawk had quite often been seen, but this bird was fast, flappy and erratic, wings looking a touch shorter or broader.  A Sparrowhawk.

Then, after four and a half hours at the rocky watchpoint, trying to force breaks in the cloud cover by willpower alone, I picked up the thin shallow arc of a medium sized raptor lifting above the ridgeline opposite.  Honey-buzzard I thought at first, and still thought after an anxious few moments when I lost it and refound it higher and closer and gliding toward my position.  That 'giant falcon' shape of a gliding Honey-buzzard approaching is so typical, the wing distinctly flexed with that forward prominence at the wrist, straight trailing edge, tail closed and looking quite long with rounded end, head inconspicuous.  Closer, its forward speed was suddenly startling, then the bird angled away giving a side view, dark against the grey sky, and then my last views were a series of broken images as it passed behind the trees to my left and disappeared over the convex slope above. Something about these last glimpses did not look right.  Was it a Honey-buzzard?  I only got a couple of poor images, but they show the bird was a Goshawk!

Honey-buzzard (left), Goshawk (right), to show similarity in silhouette of birds approaching
 in glide, rather like a giant falcon.  Goshawk 10.vi.2016.

Somewhat chastened, I resolved yet again to look thoroughly before coming to conclusions about identification.  The images show subtle differences in the silhouette that I might have seen in better light, or had I not in my mind already pencilled-in the bird as a Honey-buzzard, or had I kept binoculars on the bird instead of trying for some record images.  And the Goshawk image clearly shows the projecting undertail coverts on one side, which I did not see in life.  The bird appeared distinctly large and bulky to me, close enough to the scale of a Honey-buzzard anyway, and I now wondered if it had to be a female Goshawk; the adult male seen quite regularly now is definitely more slender overall.  It was certainly not the female that appeared over the nest woods with the male on the 7th (see previous post) because that bird was showing evidence of moult in the wing.  Why have I not seen it/her before?  Perhaps I have, but only at extreme range.

The unfamiliar Goshawk, 10.vi.2016, N Apennines

The bird I now knew to be a Goshawk flew almost directly over the nest site on its way toward my position.  I had not heard a single sound from the site in nearly five hours watch and now began to get uneasy.  The day before I had been high on the other slope of the cloud-filled valley, trying to peer through the ribbons of cloud blowing up the slope from below.  On my way down about 12.45, the cloud beginning to clear, I paused to look across over the tract of woods where I know the nest is situated.  Almost immediately I heard a sudden outbreak of loud and prolonged kek-kek-kek calls and repeated wailing, some wailing calls sounding thinner, as if from at least one large chick.  There was silence for a couple of minutes, then the whole strident episode started again.  No bird was seen leaving the scene.  But I was quite shocked by the energy put into all the calls and really wondered if something serious had occurred (wild thoughts of another Gos taking a chick, or a Marten perhaps, or the male bird even...), or could it have been just the female seeing off the male partner again?  Seeing today's large and unfamilar Goshawk made me wonder again about the cause of yesterday's violent alarms.

But then, at 14.10, I heard a quiet and short k-k-k call from the site, one quiet wail, and there was a bird arrowing away down the centre of the valley.  The male Goshawk!  So, the nesting attempt seems to be still on course.  I just hope it can withstand all this rain.

Thank you for some heat and sunshine

Male Goshawk, 7.vi.2016, N Apennines

Day after day of maddening weather in this pocket of the north Apennines.  Remorseless  dark grey cloud, heavy rain showers and wind, interspersed with thunderstorms and rare blue breaks in the cloud with precious warm sunshine.  My behaviour looks pretty crazy too.  Set off up the Goshawk valley with hope in my heart, yesterday's rain dripping off the trees and down my neck, today's rain on its way in the dark banks of cloud already descending over the hilltops, head back down having seen little or nothing of any raptors.

But what a difference a change in the weather can make!  The day before yesterday (7 June) dawned with a faint mist in the valley that soon cleared in the sun's heat to leave a blue sky, from mid-morning decorated with isolated puffs of snow-white cumulus that did not build into a pall of raincloud until late afternoon.  The kind of day that many here would regard as typical for June, unlike recent weeks, which have typified March or April.

And straight away raptors were in view: a Honey-buzzard tussling with a Common Buzzard, another Honey, whistle-calling and wing-shivering; and plenty of Goshawk activity.

I was only just completing a first scan of the ridgeline opposite, after arriving at my observation point at around 8.30, when I picked up a Goshawk flying low over the canopy further up the valley to my left.  The white undertail coverts were what drew my eye to him, otherwise I would probably have missed him against the complicated background of the wooded slope.  He moved in a diagonal up towards the ridge crest, with what looked like unusually laboured and rapid wingbeats; I wondered if he was carrying a substantial prey item but could not see clearly at the distance.  I momentarily lost my footing on the rocks and the small movement of my binoculars was enough to make me lose the bird.  I heard some k-k-k calls from the nest area soon afterwards and wondered if he had brought food.

Inset: stout body & distinct 'hand' of Goshawk

Only about 20 minutes later there was again a Goshawk in the same upper part of the valley, I assumed it was the same bird; this time he gained height and moved up the valley to fly back and forth around the rocky slopes and peaks of the local mountain.  A couple of the distant images I got show a distinct bulge in the crop, so perhaps he had recently fed.  He investigated the rock slopes for several minutes before moving decisively toward the high woodlands to my left, and out of sight.

About an hour and a half later I again heard a k-k-k call from the nest area, but very short and low key.  A few minutes later I just glimpsed the presumed male streaking down the lower part of the valley far to my right; he must have delivered prey and then left the nest area below the tops of the trees immediately in front of me.  He came back into view for a few moments, now heading back up the valley, but was soon hidden again by trees.  After a few minutes, during a period of strong and agitated kek-kek-kek calling from the nest area, with loud wails, what I presumed was the same bird came back in view around the ridgeline opposite.  This time he gained height in a combination of soaring and active flight, and performed a short display, quite like a Common Buzzard's 'roller-coaster' flight.  He made several deep but quite rapid wingbeats, rushing upward, before hanging for an instant at the apex of a steep curve then folding his wings and arrowing downward*.  Then the same again after a few seconds of lateral flight.

I was amazed, partly because I had never seen any element of Goshawk display (all my late winter or early spring visits have been marred by adverse weather or lack of visible action), and partly because I could not quite read how to interpret this performance.  It did not seem the appropriate time for a normal courtship display, because nesting is well-established by now (judging by calls), with the female presumably attending to chicks; perhaps it had a mainly territorial element.  I did wonder, with the relatively frequent sightings of a male Goshawk, if an intruding male had appeared.  At a distance, and with my poor images, I could not determine whether two males were in the vicinity.

Female Goshawk, 7.vi.2016
Apologies for very poor quality
(extreme crop of soft and badly exposed image)!

Shortly after the loud and excited calling coming from the nest area, more calling started, evidently from a bird in the air over the nest woods unseen in the deep axis of the valley below me; then another Goshawk flew actively up into view.  Clearly a different bird; less slender, and larger overall, with a rather tatty appearance due to moult.  I assumed this must be the female of the pair, the moult being consistent with nesting.  Then there was a vigorous chase up and along the ridgeline opposite, the assumed female generally harassing the male (but positions reversed in the image shown).  This behaviour is entirely consistent with several descriptions (eg. see the website cited below) of the nesting female being intolerant of the male remaining close to the nest when chicks are present, and sometimes chasing the male away. Unfortunately my camera is unable to focus on flying birds moving in front of any background except sky, so none of the images is much use.  The female soon came down to the site again while the second bird disappeared down the valley.

An outstanding morning: warm sunshine, a male Goshawk in a few moments of dramatic display, the presumed nesting female up in my sight for the first time, lots of vocalisation, some fast interaction between two Goshawks.  Of course, the birds are unmarked and I have never seen them 'at home' in the nest site woodlands, so my assumption that they are the nesting pair is just that!

Goshawk chasing; male on left, female on right in this image; mostly the other way around

*This appears the opposite from descriptions of the 'classic' display, in which most of the upswoop is without wingbeats but the over-the-top downswoop uses wingbeats.

See this brief very well-illustrated account of a watch on a Goshawk nest in England (link verified active 9.vi.2016):
http://www.thebirdsofsussex.co.uk/Articles/goshawk1.htm

The best-laid plans...

Almost missed it: distant Goshawk, 21.v.2016

I have no intention to enumerate every Goshawk sighting, but this short update is mainly to continue the more optimistic outlook I had yesterday, when it seemed that my fears over the impact of torrential rain and hailstorms on this year's nesting attempt were groundless.

Shopping and washing meant I did not get to the high landslip watchpoint until late morning.  The first quiet "kek-kek" from the nest site, unseen below me, was not until 13.15, but some more calling at 13.45, a little more urgent, mixed with a couple of "weeoo" wails, got my full attention.  I figured the calls indicated a food delivery and began to scan the airspace over the valley downhill from the nest site, the typical route of the male leaving, wishing I had a hawk's eyesight.  The tension was getting very difficult when the tiniest flicker of movement against the sky, in the opposite direction, just caught my eye.  Another Common Buzzard?  No, more agile, more attentuated appearance, and the big tail abruptly fanned out on a turn - just like a Honey-buzzard - confirmed it was the Goshawk! (image above)  It had left uphill, perhaps within the woods, or just hidden by treetops, but it was already distant.

Anyway, only a couple of poor images, but more useful information: (1) the nesting attempt seems still on course, (2) expect the unexpected!

Lucky sight: note long wings, narrow hand 21.v.2016

And there was an unexpected sighting at about 15.35, on the way back down.  The track is inside the woods, with only an occasional glimpse of the sky overhead, but lower down it turns at a right-angle and at the corner a former tractor route into an abandoned hay meadow provides a wide view of the mid and upper valley basin that I'd recently left, bounded by wooded ridges and the higher mountains beyond.  I make a point of always stepping into the corner of the meadow, partly for the open view after the closed woodland, and partly because there is very occasionally a raptor to be seen (once there was a probable Goshawk leaving a tree in the far corner of the meadow, it was off its perch and away into the darkness between tree trunks before I could blink).  Today I looked up to see a tiny high raptor passing across a cloud: it was a Goshawk, probably the same elusive male again (image above, left).  He abruptly closed his wings and fell in a near-vertical dive.  He was high over the mid sector of the valley, and I guessed he was heading for the nest, but at low level he pulled out of the dive, angling away across the canopy, and from a point on his forward trajectory a pigeon-size bird rushed up from the trees and hammered away at treetop height.  These events were all very distant, but I could see that the Goshawk made no attempt to pursue but abruptly changed course again and vanished behind a row of trees.

All's well, I think

The Goshawk departing; inset confirms identity, 20.v.2016

Much more optimistic that the apparent breeding attempt continues.  Yesterday I was nearly five hours in the landslip area in the woods above the nest site, where calls can be heard, and birds flying to or from the site can sometimes be seen.  Of course, they are not always above the canopy, and if they are, they are usually moving directly and at speed; factor in the distance between observer and site, and I always count myself lucky if I pick the bird up before it vanishes into the woods or over a ridge.

It was on what seemed like the 100th binocular sweep across the wooded ridges facing me when I picked up a distant raptor.  It seemed to have risen up from the head of the valley on the far side of the ridge opposite, but perhaps more likely had only just come into range.  The bird looked good for a Goshawk: below the overall size and bulk of a Common Buzzard, wings held flat or slightly raised, moving quite fast for its size, then as it turned across the sunlight, two white plumes like jet trails either side of the tail.  It glided across the northern face of the mountain, then looped back and forth apparently quite close to the tumbled rocks - presumably alert for prey - before turning decisively, still very distant, into the top of my valley*.  It then lost height and I lost sight of it against the complex surface of the wooded slope.

Ten minutes later there were a couple of medium strength "kek-kek-kek" calls from the nest area; ten minutes after that there was suddenly a Goshawk in the air a little downslope from the nest site, already diminishing in size as it rose up the opposite valley side and into open airspace above the ridgeline (see image above).  There was a short interaction with a much smaller raptor, I think a a Sparrowhawk, that was encouraging it to keep moving away.

Three images of the departing Goshawk; middle catches a moment reacting
to a mobbing Sparrowhawk, both birds visible in right image.

And that was all the visible action.  What I saw and heard was consistent with a male coming to the nest site, I don't know whether with or without prey, and leaving on another foraging trip.  The course he (I'm assuming it was the male) took when leaving was precisely the same as the male typically took in past years.  Around an hour later there was a single wailing "weeoo" call from the nest site; perhaps he had not brought enough food?  Let's see if a few more hours today will bring more sightings.

* I was once sitting on one of the peaks of this mountain watching at close range three Sparrowhawks, believed juveniles, zooming freely around the rocks as if in an aerial dogfight, when in an instant they vanished and a Goshawk floated into view from the cold air wrapping the sheer northern face of the mountain, like Jaws emerging from the ocean depths.

Troublesome waters...

Juvenile from the site in August 2015

Some worrying uncertainty over the Goshawk pair that I was fairly certain were starting to breed in early April.  Back then there was lots of calling from two birds, including several spells of increasingly excited screaming that I thought were likely to indicate copulation events.  But over many hours on three successive days (16-18th May) I have heard just occasional quiet k-k-k calls, mostly from different points around the middle sector of the valley, and no calls from two together.  Nor have I seen a Goshawk in flight.  Positive evidence, eg. the sound of a food delivery, can be gained in just a few seconds, but hours and hours of negative evidence, ie. failure to see or hear anything substantive, add up to nothing but a nagging worry!

On the 15th May there were severe thunderstorms and an intense hailstorm.  The storm turned out to have been far more intense around the town lower down, where the main valley meets the plain; flowers and fruits on orchard trees, grape vines, and the town centre's ornamental plants were destroyed by hailstones said to be as big as golfballs.  Given the general lack of evident Goshawk activity at the site, and the possible impact of hailstorms (I'm almost certain a breeding attempt at this site in 2013 was ended by an intense hailstorm in early June that year), I decided to make an exception to my usual rule of not visiting the nest during the breeding season, and approached the nest site close enough for a visual check.

With wind in the canopy, the network of torrents in tumultuous flow downhill, and the leaf litter soft and silent from rain, I'm confident that any bird present would not have heard me.  However, although this patch of forest is more open than most, with tall well-spaced trees and only sparse low growth to hinder movement, it is still necessary to approach to around 100 metres to find a sightline for binoculars downhill to the nest through the dense screen of intervening lower canopy leaves, and I doubt it is possible to do so unseen.

The next 15 minutes were increasingly tense, as there was no sign of a sitting bird, such as a tail projecting over the nest rim, and no sign of any green leaves having been added, and, at distance and in confusing light, it was too easy to turn any moving leaf shadow or any leaf turning brightly in the sun into some part of a hawk.  But eventually a distinct grey-brown crown raised slightly above the rim a couple of times and disappeared down again.  I could not see any more detail, certainly not an eye, so cannot be certain if the bird saw me, but strongly suspect she (?) had seen me through a gap in the woven sticks of the nest rim as I approached.  She sat tight, I hope on eggs or chicks, without alarming and there was no alarm from any partner perched unseen in the vicinity.

I retreated as unobtrusively as possible and climbed further up the valley to an open rock area from which it is sometimes possible to see birds in flight after they have left the nest site, and always possible to hear any vocalisations from the nest or nearby parts of the valley.  Nothing seen or heard, but I only had about three hours available, so could easily have missed visual or auditory evidence of any interaction.

Although I did not conclusively identify the bird occupying the nest as a Goshawk, I'm pretty sure it was, but now the comforting thought that a bird is in residence is turning into renewed worry about the fate of the assumed breeding attempt after another several hours of intense thunderstorms (but no hail) today, Thursday 19 May.

Goshawks 2016: early spring, a pair on-site again!

Goshawk leaving nesting site,
N Apennines, 1 April 2016

So different from the heat-hazed green slopes of summer, the north Apennines in winter can feel austere and unwelcoming, the naked contours of the land revealed through the leafless trees, sometimes layered with snow, sometimes showing only the pale brown carpet of dead leaves. But by late March, flowers of Cornelian Cherry (Cornus mas)and Italian Maple (Acer opalus) stand out here and there on the hillsides, patches of yellow and yellow-green  among the vast grey-brown expanse of bare beech and oak branches.

Already a bit late in the year, I was resigned to not seeing any Goshawk display flights (and never have done because every late winter visit so far has coincided with low cloud or rain or thick snow), but I still hoped at least to confirm the presence of Goshawks, and perhaps get some idea of the chances of nesting in the side valley used in several recent years.  To hear something would be fine, to see a bird would be great.

I arrived on March 30th to find the hills slightly brighter than the cloud-covered Po plains, with a few moments of veiled sunshine, but it was windy and cold as I set off uphill in the late afternoon.  Nothing seemed to be moving in the silent hills, and the weather was hardly uplifting, but after about an hour I heard a faint and slow "ke--ke--ke" from the centre of the valley ahead.  As I continued uphill, the calls became faster, more urgent, and then a female joined in: "wee-oo, wee-oo, wee-oo". The calling subsided as I reached my destination: the top of a small steep meadow enclosed in the woodland where the open slope allows a reasonable view over part of the tree-filled central axis of the valley, including the area where the Goshawks nest (the only Goshawk nest I've found in the area).  Although the nest itself cannot be seen, nor can the nest tree be picked out from this viewpoint, any calls in the vicinity can readily be heard and the birds themselves can very occasionally be seen in flight.  Any such views are unpredictable and usually fleeting (the adult male may be more active during nesting but seems mainly to arrive unseen below treetop height, and typically heads down the valley from the nest close to treetop height and does not appear in open airspace until a couple of hundred metres downhill).

Cornelian Cherry (left), Italian Maple, flowering in March 

As another spell of calling started, first slow, then more urgently, it was suddenly reminiscent of summer last year, listening to calls around food delivery or wails from young wanting food.  Then at about 19.00 hrs, as the weak late light lifted toward the higher slopes, the calling quite suddenly became more intense, faster and louder, so the single wailing cries of the female for a few seconds turned into a sustained "wee-oo-wee-oo-wee-oo", like an emergency vehicle siren.  I guessed this probably marked a copulation event, which can be noisy and very frequent in the period before egg-laying (see Cramp & Simmons, 1980, Kenward, 2006, and sources therein).

Even without sight of the hawks it is marvellous just to be certain they are there and to revel in the sense of wild nature their energetic calls evoke.  But crucially, I now knew that a male and female Goshawk were present, probably a mating pair, and they were in the precise area of woods where a pair has nested in several previous years!  That was the information I had been hoping to gain, so anything else would be a happy extra.

The following day (Thursday 31 March 2016) I headed up the opposite side of valley on the old track through the woods that passes at one point within about 100 metres of the nest tree (see "Nesting Site" page), then headed off at a right angle to the valley axis up to a small patch of landslip boulders within the woods.  This site does not give a view directly onto the canopy of the nest area but does allow a reasonable view of part of the airspace above it, and allows calls in the area to be heard clearly.  Typically a bird does not fly up straight from the nest but glides far downhill below or barely above treetop level before emerging briefly into view a couple of hundred metres away; such birds are very easily missed.

Distant, but certain Goshawk,
31 March 2016, N Apennines

There were a few relaxed "ke--ke--ke" calls through the morning, and a few short spells of wailing, but I had no clear idea of recent events at the nest when at 11.30 I caught sight of a distant raptor just breaking the skyline of the opposite ridge having apparently risen from the valley bottom some way downhill.  Looking slightly like a scaled-down Honey-buzzard in shape, quite long-winged, large tail fanned widely in turns and twisting one way and the other. Clearly a Goshawk, it stayed relatively low while moving up along the ridgeline opposite and then disappeared out of sight on the far side of it.  I would have bet good money that it had left the nest area moments before, glided a few hundred metres down-valley across the treetops and then started to climb, as the foraging male habitually did in previous seasons. The bird was distant when I first saw it but one tiny image shows a typical Goshawk shape, including the longer arm and narrow hand (relative to Sparrowhawk).

Silence until about 13.00, then more "ke--ke--ke" calls, then faster "kek-kek-kek", then some soft "wee-oo" wailing.  Calls gradually became more frequent until about 13.30, when a loud semi-duet turned into the same fast siren-like "wee-oo-wee-oo-wee-oo" that I'd heard the previous evening.  I guessed this was another copulation event.  Then about an hour later on my way back down to the village, I was next to the track on a slight prominence below which the ground falls away steeply toward the central torrent, and peering past the tree trunks into the open airspace beyond, when I saw a Goshawk gliding through the haze above the wooded depths of the valley, not yet distant and initially almost at my eye level.  Trying to track it as it moved in wide circles (appearing very leisurely but covering a lot of ground with scarcely a wingbeat) I soon lost it, obscured by the dense screen of bare branches rising from the slope below, but saw it for long enough to note a large bulge in the crop.  I could not tell the sex but wondered if this could have been the female, perhaps after consuming food provided by the male earlier in the day?

Friday 1st April, same location. Most cloudy with occasional weak gleams of sun, chilly. Two tractors were in a patch of thinned woodland on the opposite slope, noisily collecting logs cut last summer. Goshawk calls continued as before, with long periods of silence, then spells of low intensity calling, then sometimes louder and more urgent, sometimes apparently both male and female.  But I could not sense a definite pattern and could not visualise possible events in the nest area.  Then, with no hint of any interaction at the nest, a Goshawk was suddenly in the air above the site; it banked rapidly and flew fast but with few wingbeats downhill and out of sight beyond the wooded convex slope below.  I just had time to register the generally pale underside as it banked (ie. an adult bird) then grey-brown dorsally, a few dark tail bands, white alongside the tail base and a dark mask-like patch behind the eye.  Only managed one image before nearby branches got in the way.

Saturday 2nd. Similar phases of quiet and of calling. Mid-morning loud wailing calls and kek-kek-kek calls suddenly from trees close on my right but no bird visible and no bird seen to fly there. Confusing and frustrating! Then one glimpse of a raptor plummeting from that area toward the stream channel in mid valley. During the next hour there were just a few calls, apparently from a bird moving from tree to tree in the nest area, until a little after midday there was an excited "kek-kek-kek-kek" from the site and several seconds afterwards I just picked up a hawk heading for the nest site in a shallow but very fast dive from a point above the lower end of the valley. The bird at the nest site must have seen it approaching well before I was able to. It disappeared into the canopy, possibly a little way uphill from the actual nest site, without checking speed. I had never before seen a bird arriving at the nest site! I could not see if it brought prey, but there were soon spells of "kekking" and some wailing which accelerated to a shrieking crescendo, followed by silence...

So, a very productive visit: calls confirmed presence of Goshawks at the nest site, apparently a mating pair, with a couple of lucky sightings of birds in flight (and on April 1st I heard my first cuckoo of the year!).  If my calculations are correct, working back 75-80 days from apparent fledging around late June/early July in recent years, the female could even be laying during the next week.  Indications are that they may have already chosen to nest again at the known site.  Must not tempt fate but I am daring to hope that things turn out this way, and that I'll be able to listen and look for them at intervals over the coming months.

Cramp, S & Simmons, K E L (eds.). 1980. The Birds of the Western Palearctic, Vol II. OUP, Oxford.
Kenward, R. 2006. The Goshawk. T & A D Poyser, London. (reprinted 2007).

First thoughts on Goshawk identification

Adult male Goshawk: distinctly protruding head,
full body, rounded tail tip, wings proportionally
 longer than Sparrowhawk, clearly narrowed hand.

For a UK birder with no experience of seeing Goshawks, or very little, the question of identification looms large; in particular, how to distinguish the species from Sparrowhawk in flight.  Although field guides and other sources provide plenty of pointers, it can be difficult for an inexperienced observer confidently to separate these species because this often involves subtle differences in proportion or flight behaviour rather than discrete colour and pattern features.

Some sources minimise the purported difficulties and stress how clearly different the two are in respect of several key features; some suggest, perhaps partly 'tongue-in-cheek', that if there's any question over identity, then the bird is probably a Sparrowhawk because the Goshawk stands out by its presence and flight behaviour.  But it has taken me a long time, and many views of Goshawks in flight (occasionally at quite close range rather than a distant dark speck in the sky), to start seeing the differences with any confidence.

Almost all my sightings have been of adult male or juvenile Goshawks; the former typically while leaving the nest site after prey delivery, and the latter as they become increasingly active in flight in late summer.  I have never yet had prolonged views of an adult female (and have never yet been able to watch birds in display because the hills seem invariably covered in snow or cloud or rain when I've visited in late winter/early spring!).

A small selection of sources on Goshawk recognition that I've found particularly useful, beyond the usual field guides, is listed at the end of this post. Orton (1989) has a few words on goshawk field identification: "...the goshawk wing looks proportionally longer than the spar's and is often beaten with a more leisurely stroke...the head of the gos protrudes relatively further...the tail, relatively shorter, spreads to end with a more pronounced curvature..." (slightly abbreviated from paragraph on pp218-219).  Pertinent, concise, and perhaps the most useful short summary available?

In my limited experience, I think the differences in (1) wing and (2) head shape tend to be the most easily seen features in flying individuals, the former usually more obvious than the latter, and aspects of (3) tail shape can provide a secondary source of information.  These structural features are discussed and illustrated below; some non-structural features (plumage patterns, flight style) may be noted in later posts.

Composite image to show some key features for identification.  In Goshawk (right, adult male, June 2015) note in particular: proportionally longer wings, protruding head and wider neck section, width across breast and belly, tail with strongly convex end and here parallel-sided when closed (often tapering).  The head protrudes very little in the Sparrowhawk shown (left, September 2011), the body is slimmer, the tail in this individual is somewhat angular at the corners.  The fact that the Gos shown is a larger bird than the Sparrowhawk can be gauged from the apparent narrowness of the head; the head would in fact be as wide or wider than the Sparrowhawk but appears narrow mainly because the Gos was much further from the camera.

(1) The extended wing appears proportionally longer in Goshawk than Sparrowhawk.  

Both the 'arm' (from the trunk out to the 'wrist' = carpus) and the 'hand' seem to contribute to this appearance, ie. both wing sectors look fractionally more elongated in Gos compared with Sparrowhawk.

Also, the Goshawk hand is typically slightly narrowed in relation to the secondaries (front to back), ie. the trailing edge of the wing tends to show a distinct S-curve, convex along the secondaries then narrower from the first primary outward (see the last post on the thread HERE, last accessed 23.i.16, which presents ratios derived from approximate measurements of images of both species).  This slight narrowing probably contributes to the overall appearance of wing length.  By contrast, the trailing edge of the Sparrowhawk wing tends to show a simpler curve; the section of hand made up by inner primaries is usually less distinctly narrowed in relation to the secondaries, and the primaries overall often look rather like a spread fan radiating from the end of the wing with scarcely any distinct 'palm' to the hand.

Of course the shape of the wing varies according to flight mode, eg. the degree of extension or flexion at the wrist, and age and the stage of moult (so if one or two inner primaries are missing, the Sparrowhawk wing can show a similar S-curve often seen in soaring Goshawk).  Looking at a live bird in flight, rather than an image, it can be difficult to register the narrowing of the hand in relation to the secondaries but it probably contributes to the long-winged impression.

Composite image to show some key features for identification.  In Goshawk (right, adult male, June 2015) note in particular: protruding head and wider neck section, width across breast and belly, tail with slightly convex sides and rounded corners.  The fact that the Gos shown is a far larger bird than the Sparrowhawk (left, June 2015) can be gauged from the apparent narrowness of the head; the head would in fact be as wide or wider than the Sparrowhawk but appears small mainly because the Gos was more distant. The stronger S-curve of the Goshawk trailing edge and narrowed hand can be seen.  The head protrudes very little in the Sparrowhawk shown, the body is slimmer, but the tail end in this individual is quite convex and similar to the Goshawk.  Note also the narrow tail base of the Sparrowhawk even when the tail is closed, in contrast to the Goshawk shown, where the tail is closed but appears parallel-sided because of the greater width across the tail base; often in Gos the closed tail tapers distally because of the wide 'hips'.

(2) The head tends to appear more prominent in Goshawk.

This greater prominence is in part because the neck is often somewhat extended in flight, seemingly reflecting the effort put into active flight or prospecting for prey, and in part because the bill is proportionally larger, both longer and deeper.  The head usually looks less prominent in Sparrowhawk; the neck is not routinely extended and the bill is often scarcely visible.  Hence the distinct flight silhouettes, often described as 'T-shaped' in Sparrowhawk and 'cross-shaped' in Goshawk.  But this typical difference is not fixed: the Goshawk may fly without the neck fully extended, and the Sparrowhawk head can appear prominent if the bird is actively looking around in flight.

On the Sparrowhawk shown (left) the head is somewhat protruding and Gos-like, but does not show the distinct extended neck often seen in Goshawk; the Goshawk (right, juvenile) has the head withdrawn and tilted down a little and so looks small-headed and very like a typical Sparrowhawk in this image.  The Sparrowhawk shows the typical proportionally shorter wing with a slight step between arm and hand, and the hand appears short and not distinctly narrowed; in the young Goshawk the trailing edge shows the characteristic S-curve, with hand distinctly narrower than secondaries.  The Sparrowhawk tail, partially spread, arises from a proportionally narrower base, with a relatively straight end and is angular at the corners.  The hips of the young Gos are not as wide as in adults but the half-spread tail shows a well-rounded end with rounded corners.

(3) In Goshawk the tail typically has a rounded end if closed, and rounded corners if spread.

The tail in Goshawk typically shows a distinctly rounded end when closed, and at various degrees of spreading the outer tail feathers still show rounded tips.  In contrast, the Sparrowhawk tail can look quite straight-ended and usually has squared-off corners whether closed or spread.  The state of moult affects the appearance to some extent. I find it difficult to perceive a consistent difference in relative tail length; some sources (like Orton, cited above) state the tail is proportionally a little shorter in Goshawk (others suggest the opposite).

For brief notes on Goshawk identification, with several very impressive and informative images, see:

http://andybutlerdiaries.blogspot.co.uk/2015/09/goshawk-flight-identification-and.html

Darlaston, M. 2008. That tricky accipiter. Devon Birds 61 (1) (April): 18-23.

Jowett, A. 2004 (?). 3 page discussion of Goshawk identification, available in pdf at www.bradfordbirding.org/ARTICLES/Goshawk.pdf
(note added 30.04.2017: this article apparently no longer available on bradford site)

Orton, D A. 1989. The Hawkwatcher. London: Unwin Hyman.