We who were so fortunate to be on the Falsterbo peninsula studying migrating raptors on October 8^th 2017 will remember this day as long as we live. A record number of 16.655 Common or Eurasian buzzards (Ormvråk – Buteo buteo) flew by together with a lot of red kites and sparrow hawks. It was like one big current of raptors floating by. One started to expect a very good day a few days earlier. Two days before about 6000 passed, and the day before, there were reports of large numbers of buzzards being seen at various places north of Southern Scania. But still nobody could expect that all-time high record number of Eurasian buzzards.

As a nature photographer, I started to photograph the current of passing buzzards. First, I just wanted to take as good photos as possible. But I soon realized that this was a golden opportunity to study buzzards from a large part of Northern Europe in one place, learning more about the great variation of the plumages of the juveniles, the post-juveniles, and the adults. Of the many photos taken, 49 were good enough close-ups to be possible to study in detail in the computer. 28 were identified as juveniles, including a few post juveniles, and 21 as adults. The photos of the adults are divided into six main forms of plumages or morphs and shown below.

Adult underside morphs

The underwing of all adults photographed is barred with dark-tipped secondaries and inner primaries, forming a dark band. The outer primaries are whitish-based, while the tail is barred with the terminal band being broader.

The differences underneath between the individuals photographed mainly concern the colour of the feathers of the head, body and wing-coverts, whether they are dark or light. Depending upon the colour of these parts a distinction is made between six types of morphs. The classification of the photos along these forms are based on the book ‘Rovfåglar i Europa’ (Raptors in Europe) from 2006 by Benny Génsböl.

As illustrated by Photo 1 below, both the body and the wing-coverts of this raptor are predominantly dark, hence this buzzard is defined as belonging to the dark morph. These parts of the adults shown on Photos 2 and 3, on the other hand, contain lighter elements, especially the secondary coverts, making the plumage motley. This morph is defined as normal, having a plumage in-between dark and light. The next type is named the dark light morph due to mainly the lighter body and greater coverts (Photo 4).

The body and the underwing-coverts of the buzzard on Photo 5 have more light parts than the previous form, therefore being classified as the almost light morph. The light morph shown on Photos 6 and 7, has most of the underside light, since major parts of the body and the wing coverts are pale with certain dark parts. The very light morph on Photos 8 and 9 is very pale, since these buzzards lack bars on most of the body and wing-coverts as well as on parts of the flight feathers, the bird on Photo 8 only having a dark terminal band on the secondaries, and the tail. This adult is also the only one found to have a clear comma on the primary coverts. But this is also a trait of juvenile common buzzards.

Actually, it can be difficult to determine the age of buzzards that have such few distinguishing characters as the light and very light morphs, especially if the evaluation is based on photos of the underside alone. The bird on Photo 9, for example, is especially hard. The dark terminal band on the secondaries and the faint such tail-band indicate that it is an adult bird. But the lack of such a band on the inner primaries and the few streaks on the breast indicate a younger bird, a juvenile or a post-juvenile. Such an evaluation is complicated further by that there are also light morphs of other species of buzzards. In this particular place, rough-legged and honey buzzards are common.

 

The photos of the juveniles and post-juveniles taken during this ‘Golden day’ of October 8^th have been classified in the same way as the adults above. The result of this grouping is reported on the next page.

Conclusions

Based on the photos below of adult common buzzards and the photos of juveniles and post-juveniles on the next page, one might question some common ‘truths’ about how to separate common buzzards from other raptors and particularly in determining how old they are:

• According to many field guides, there is always a lighter band across the lower part of the breast, irrespective of morph. However, many birds photographed lack this characteristic, in particular the light and very light morphs.
• Based on the analysis of the photos and Génsböl (2006), it is too crude to distinguish between only two  morphs. There are at least three types of light and dark adult and juvenile common buzzards. For example, what does one mean when one reports a ‘Börringevråk’ (a nickname for the Swedish light morph)? Is it an almost light, a light, or a very light adult or juvenile?
• The presence of a distinct ‘comma’ on the primary coverts seem to be exaggerated, since I only found a few such cases among all the lighter buzzards photographed. This has mainly to do with that that there is a much greater variation of light plumages than is usually taken up in the field guides, i.e. they simplify too much.
• In the field, the terminal tail band of adults is not so distinct and broad as shown in many field guides, which makes it harder to distinguish between old and young common buzzards.
• The lighter median underwing-coverts are only found in some adults, naturally not for the light and very light morphs.
• It is very difficult to determine the age of these paler forms in the field.