Honey-buzzard in Scotland

The impression until recently has been that the Scottish population of Honey-buzzard is poorly known. However, as discussed below, publication of The Birds of Scotland in 2007 has revealed much more information than was in the public domain before. This development is very welcome. We also discuss below the exciting find of a Honey-buzzard concentration in central Scotland in 2016, as reported in Scottish Birds.

The table below summarises observations made by NR from 2000-2016 in Scotland. No visits were made to the country in 2005, 2011, 2013-2014, 2016.

Area

Year

Month

Number birds

Number sites

Ullapool

2003

May

0

0

Skye

2007

August

0

0

Skye

2008

September

0

0

Skye/

Torridon

2010

May

0

0

Inverness

2000

May

1

1

Inverness

2001

May

3

2

Inverness

2006

May

4

4

Inverness

2012

May

3

2

Aviemore

2003

May

3

2

Aviemore

2006

May/June

1

1

Perth

2001

May

1

1

Perth

2003

May

5

4

Perth

2006

May/June

2

1

Perth

2006

August

3

3

Perth

2007

September

4

2

Perth

2008

September

1

1

Perth

2009

September/October

2

2

Perth

2010

May

1

1

Perth

2012

May

1

1

Perth

2015

September

4

4

Callander

2008

May

9

5

Glasgow

2002

May

2

1

New Galloway

2004

May/June

12

7

Total -- distinct sites

 

 

50*

32*

 

Area means roughly the land in a 40km radius of the named town or city. The site near Inverness at which birds have been satellite tagged is not included in the above totals. The overall totals are 32 sites including Perth 10; New Galloway 7; Inverness 7; Callander 5; Aviemore 2; Glasgow 1; Skye 0; Ullapool 0.

These are very much opportunistic sightings in visits lasting one week each year. It would be interesting to see more comprehensive figures if these are available.

The total of 32 sites above is significantly above the 14 reported for Scotland in the last UK results for 2000. It is though within the 30-50 pairs estimated from a recent habitat analysis for the whole of Scotland (see density studies). Certainly the nature of the above survey does not allow an extrapolation to be made for population purposes but the widespread distribution of the Honey-buzzard in Scotland is surely not in doubt.

The Birds of Scotland/Other Literature

Some interesting comments are in Scottish Bird News (no 86, December 2007, p.8, report on SOC Conference held on 2-4 November 2007). The population in Highland reached 15 pairs in the early 1990s and breeding was noted in Perth & Kinross and in Dumfries & Galloway at the same time. Most breeding attempts (93%) are successful. The species is probably overlooked as a breeding species in Scotland and may be more widespread, maybe reaching 50 pairs (From talk on European Honey-buzzard by Brian Etheridge with his summary).

These comments are based on the account for the European Honey-buzzard by Brian Etheridge (2007) in The Birds of Scotland. This account has a number of interesting points:

The report of the Scottish Raptor Monitoring Scheme for 2006 showed that effort was rather low in searching for breeding Honey-buzzards in Scotland with just 5 home ranges visited by Highlands RSG and none by other RSG.

In 2011 it was estimated in The Scottish List that 15-20 pairs bred in Scotland (Scottish Birds 31, Supplement 1, pp.10-11 (2011)).

Short note: McInerny, Christopher J, Honey-buzzard carrying a reptile during display flight, Scottish Birds 34(2) p.143 (2014). Author believes this is the first report of a reptile being used as a visual prey item during display flight by Honey-buzzard in Scotland. Comment by Brian Etheridge: “I have not witnessed this before, though I have watched this species display many times. Display in the late summer is quite frequent and appears to be made by non-breeding adults. It is often followed up the next year by a breeding attempt in the wood over which the display occurs.”

Comments by NR: NR has readily found birds in the main breeding areas cited by Etheridge (2007) but has also found significant numbers in Dumfries & Galloway where further study is required (by everybody) and around Callander (including the Trossachs) in Stirlingshire. In Northumberland the few times in which forestry operations have affected birds has caused the loss of the nest for that year and the birds have not moved into the nearest available wood: they appear to seek available optimal habitat within the same general area. So the apparent decline in the Highlands may be due to the whole area understandably not being searched each year.

Display in spring is very variable in Northumberland, being dependent on fine weather. The activity in July and August noted above (and in Wales) is very rare in Northumberland, perhaps because it is due to contention when optimal nesting sites are scarce and this state has not been reached yet in Northumberland. Fledging in Northumberland runs from mid-August (not early August) but fledging is counted as birds above the canopy which will inevitably be later than the strict time when the bird first flies within the tree cover. Routinely some birds fledge in Northumberland in early September. Fledging success is also high in Northumberland at c90% per breeding attempt: it is difficult to give a more precise figure as attempt needs to be carefully defined. The number of juveniles fledging per brood is apparently lower in Northumberland (1.3/successful nest in 2007) but the methods are different. Ringers often measure the number ringed whereas the number appearing above the canopy is the measure used in Northumberland. The fatality rate between ringing and appearing above the canopy may be significant and not all juveniles may rise readily above the canopy.

There is considerable difference between the tree species used for nests. In Northumberland Scots Pine and Norway Spruce are preferred in coniferous plantations and Oak in deciduous woodland. Northumberland preferences seem closer to those found in the work in Holland (Bijlsma 1993) than in Scotland: it does depend on the trees available and the areas selected by the observers to actually find nests. Spacing between nests in Hexhamshire in Northumberland, where a large area provides suitable habitat, is 2.5km, very close to the 2.7km found in Scotland.

Timber operations have so far in Northumberland been a very minor threat but if the private owners are tempted at some stage by high timber prices to do extensive felling this could cause significant problems. The success rate in Northumberland does not suggest that egg collectors are the problem they are made out to be. Birdwatchers in Northumberland have also not been a problem as the time that needs to be invested and the subtleties of identification have proved to be major barriers.

By 2014 when McInerny published his note, it appears that at least some raptor workers in Scotland are being more candid about the growing population of Honey-buzzard in the country. Brian Etheridge is based in Inverness.

Scottish Birds paper: KD Shaw, CJ McInerny, A Little, K Little, JS Nadin, R Goater, An exceptional season at a central Scotland Honey-buzzard study area, Scottish Birds 37(1) 3-13 (2017).

It is very satisfying to see a report of another successful Honey-buzzard study area in the UK. The site is kept secret but it's possibly the Tay Valley, Perthshire, which I have claimed several times as an area rivalling the Tyne Valley for Honey-buzzard. The study was made last summer (2016) so it's very topical.


Some specific comments:


p.4 History of Honey-buzzards in Scotland. The statement “However, many ornithologists who study Honey-buzzards, including the authors of this paper and the RBBP, believe that published UK population numbers are an underestimate” is strongly supported.


p.5, p.9-10 Study area has extent of 90 km2. Five pairs bred: how does this compare to the Tyne Valley study area? It's good to deal in the distance between pairs, which is given as 3.5, 3.5. 3.0, 3.0, (all km) in the Scottish study, giving an average of 3.25km. The comparable distance is 2.5km in the Tyne Valley study area. In terms of habitat Northumberland has less large conifer blocks in the Tyne Valley than in the central Scotland study area, with more mature woodland in deep valleys.


p.6 Study area. Only two raptors, Common Buzzard and Goshawk, were seen interacting with Honey-buzzard. In the Tyne Valley study area, Hobby is the main interacting species at display time with Common Buzzard keeping a very low profile. At fledging time Common Buzzard is the main interacting species, particularly if the Honey-buzzard have nested fairly close to the Common Buzzard, but the aerial battle with Hobby goes on through the whole season. Hobby are scarcer in the Tay Valley than in the Tyne Valley but I have found a few there. Sparrowhawk also occasionally mob Honey-buzzard.


p.8 The number of non-breeders is much higher than in the Tyne Valley study area and the peak activity in July for aerial activity is not the pattern in Northumberland. It appears that the intense interaction between breeders and non-breeders causes the activity when the young have hatched. The Honey-buzzard in the Tyne Valley study area are almost invisible in July, only becoming active in the air a few days before fledging from mid-August. The number of non-breeders may be determined by how much surrounding habitat exists for a natural dispersion of 'new' breeders. Obviously this is an area for further study. There is a possibility that an unusual number of non-breeders were present in 2016, giving much more interaction than in a normal season and making the population much more visible than usual.


p.10 Young fledged from third week of August. This is exactly the same as in the Tyne Valley study area where at the lower altitude areas in the valley, young fledge from 15/8-22/8. At higher altitude, on the moorland edges in the Tyne Valley study area at up to 450m asl, young fledge significantly later, mainly in early September with a few as late as mid-September. Juveniles in the Scottish study were seen on 21/8, 24/8, 27/8, 6/9, 7/9, 11/9. This is very similar to the picture in Northumberland for lowland sites but at upland sites juveniles can be seen for about a further 2 weeks up to almost the end of September (27/9 in 2016). It is very significant that the juveniles were seen above the canopy: Roberts in his review of the Northumberland Honey-buzzard claimed that juveniles were never seen above the canopy: a result perhaps of a failure to recognise the juvenile's different shape and plumage.


Juveniles continue to appear in Northumberland until early November. These are thought to be migrants, from Scottish bred sites. The numbers vary considerably from year to year. 2016 was the 2nd best year on record with 22 juveniles noted in Northumberland (9/9-4/11) and 4 in the Lake District (9/10-12/10). Other good years have been 2014 (20 juveniles in Northumberland), 2012 (27, best to date), 2011 (12), 2008 (14). There may be a correlation with breeding success in Scotland. Since these are just opportunistic sightings, a substantial Scottish breeding population is indicated. The juvenile migrants (and locally-bred birds) seen in 2016 have been analysed in terms of colour-phase.


p.11 Breeding success is given as 7 juveniles raised by 5 pairs, that's 1.40 young per successful nest. In the Tyne Valley study area 1.69 young were raised per nest in 2016 with all 49 sites being successful.


p.12 Advice to others … Suggested survey time of July/August is very suitable for raptor workers, involved in other studies of earlier breeders such as Goshawk and Merlin, indeed of all other raptors except for Hobby. You are though vulnerable to being criticised as in the old saw: “Why are you looking over there: I thought it was lost over here: because the light's better over there!”. Someone targeting Honey-buzzard as top priority should definitely get out in the spring as you get a clearer perspective on what is going on.


It is worth noting that for birds fledging in mid-August, the laying date will be 80 days beforehand, at the end of May. So the adults will be sitting at this time, severely reducing visibility. The adult male in fine weather does do high circling right over the nest site at the start of the incubation period but this is difficult to detect on a casual basis as unless the bird is seen soaring it may be overlooked; such display is presumed to be a deterrent to the settling of late migrants, mainly young birds without territory. The pair apparently cease mutual display just before the first egg is laid. A fledging date of mid-August is associated with lowland sites in the Tyne Valley study area, where display is conspicuous in mid-May. At higher altitudes fledging is later so display might well be noted from late May to mid-June. So spring-watch is to be encouraged, with mid-May for lower altitudes and late May to mid-June for higher altitudes. Birds breeding on the edge of the grouse moors appear to breed the latest, maybe to coincide fledging with the peak productivity of the heather moor.


Identification is more challenging in autumn than in spring as Common Buzzard juveniles are readily confusable with Honey-buzzard juveniles. Identification is easier in May/June as Honey-buzzard is often the only displaying raptor, other than Hobby, with Common Buzzard on eggs or with small young. So understanding the spring position gives a solid baseline from which to work in the autumn.


p.12 Acknowledgement to FCS for sympathetic management of forestry. There are also some very good private forests in central Scotland, e.g. those belonging to Duke of Atholl.


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