Summer ends & even the juvenile Goshawks disappear

Juvenile (Northern) Goshawk Accipiter gentilis, N. Apennines, 29.vii.2016
The slightly bulging crop indicates the bird had recently received food

Returning to the Apennines on 20 August after a week at home it felt as if the breeding season had come to end while I'd been away.  Nothing seen or heard since then has changed that impression.  So, from a happy period when a sight of Goshawk in flight could almost be relied on at some point during the day, to now, when there is scarcely any evidence that there is a Gos anywhere in the vicinity.

Male Goshawk, distant bird in the dull cloudy conditions typical
of spring 2016 in the north Apennines. 

That 'happy period' extended from late spring to late summer, chiefly when the provisioning male of the nesting pair was most active in May and June, and then when the fledged juveniles started open flights above and beyond their natal woods in late July and early August.  The traditional period for Goshawk watching in the UK extends over a couple of weeks in late winter and early spring when adults display over established or potential breeding territories but (as noted in a previous post) my visits to this Apennine location, hoping to see display, have always been hampered by cloud or rain or snow.

No sightings at all since I've been back, and just one "kek-kek-kek" call from the nest area on two different days, sounding full and robust so perhaps an adult.  I probably inadvertently triggered the first of these because it coincided with me walking along the track that passes through the nesting woods; although I never like to cause any disturbance, I was pleased to be reassured that one of the hawks was still present.

Juvenile Goshawk, N Apennines, 28.vii.2016

I'm pretty certain that time spent at a watchpoint overlooking the nesting area now would probably be better used elsewhere, but it remains to be seen if Goshawks will be seen during less narrowly focused excursions into the hills. I have very occasionally seen them flying in autumn in past years but never worked out a way to increase the chances of contact.

There may be one opportunity: I have previously seen distant 'probable' Goshawks around the craggy rock peaks of the local mountain toward the end of the year, and the provisioning male was often seen heading that direction (and one once showed up for a split second to terrorise and scatter a group of three juvenile Sparrowhawks I'd been watching ducking and diving around the main peak).  But very long odds indeed on being up there at the right time and looking in the right direction!

Schedule of events at and around the Goshawk nest site, 2016

End March to start April

Much activity in immediate vicinty of nest tree by adult pair; lots of calling, including several phases of loud and increasingly excited screaming, probably signalling copulation events.
(estimate laying around mid-April, hatch late May)

Late June to late July

Young are heard calling but apparently remain under or within the tree canopy for three or four weeks once presumed able to fly (I do not know the actual branching and fledging dates because I do not attempt to directly monitor the nest and surroundings).

Last week in July.

The first few flights in open airspace above the canopy. These tended to extend only within a few hundred metres of the nest site, with both juveniles remaining relatively close (estimated up to about 200 metres apart).  (I was uncertain if there was a third less advanced bird at this period, and still have not seen more than two juveniles together).  During what I assumed is a food delivery by an adult, often signalled by a kek-kek call, juveniles still tended to converge from separate locations up to perhaps 400 metres away, screaming excitedly.

First week in August

Flights became distinctly more ambitious about a week after their first extensive flight in open airspace above the nest valley, and each of the two juveniles started to take their own separate flightpath.  Birds were seen to soar higher, almost out of (binocular-aided) sight; they have been seen to overfly adjacent valleys and mountain blocks, at least one or two kilometres distant; they have interacted with other raptors.

Second week in August

As the first week to 10 days of flights strongly centred around the nest location ended, during the second week of August in the present case, there was also little evidence of  juveniles congregating excitedly when food was brought.  Once I heard birds calling apparently in response to each other but with no auditory sign of any movement toward each other.

End of August

Where are they now? With no visual or auditory evidence of their presence by the second half of August, I have no way to know whether the juveniles have permanently dispersed or are still present for some periods in their natal woods.

Typical juvenile movements

I tried to relate these observations to the typical behaviour of young as summarised on p146 of Kenward (2006, also see more substantive text in the Markers and movements chapter):
"After fledging to neighbouring trees, Goshawks remain within 300m of the nest for about three weeks until their flight feathers harden, at 60-65 days old, after which they routinely move within 1km of nests but with occasional excursions up to ten kilometres away".

It seems likely that the major part of July, during which I heard young calling and moving within the woods toward a food delivery, but did not see them, corresponds to a first phase of spreading from the nest prior to the 65-day threshold when the flight feathers are fully developed.  The last week in July showed the start of open flight above the woods but mainly together (two juveniles) and mainly within the nest valley, and within just a few hundred metres of the nest.  According to my observations juvenile flights became quite suddenly more ambitious over the first week of August, with juveniles flying separately, going to great height at times, and moving at least a kilometre or two to adjacent valleys and hillsides.

 If the 65-day threshold corresponds to the start of above-canopy flights by the two juveniles together, that would place the hatching date around 20 May and laying in mid-late April. Whatever the dates involved, it was satisfying to find that my observations about juvenile movements under the canopy, free flights in open airspace above the woods, still with some social cohesion; followed by longer distance individual flights, less cohesion, and probable dispersal, are in accord with far more precise observations by others, notably the radio-tracking studies synthesized in Kenward (2006).

Summer ends...

Apart from lack of visible Goshawks, autumn is clearly approaching.  There is not quite a chill in the early morning air, but certainly a freshness.  One apparent sign of autumn is slightly misleading: the extensive areas of brown that have spread over the hills are not autumn leaves, about to fall, but the hop-like fruits of Hop-hornbeam Ostrya carpinifolia, which appear in summer and seem unusually abundant this year (below, left).  But now the air is often filled with the mysterious soft fluting calls of Bee-eaters Merops apiaster, moving away from their breeding sites in the lowland; "mysterious" because their loose and open groups (below, centre and right) are often high enough to be almost out of sight.  It is a clear signal of the approach of autumn because their calls are never heard here in the mountains except during a week or two at the end of summer.

Fruits of Hop-hornbeam (left), Bee-eaters (centre and right). N. Apennines. 

Kenward, R. 2006. The Goshawk. T & A D Poyser, London. (reprinted 2007).