Question about western marsh harriers (1 Viewer)

[JayFeatherPL]

Looking through photos of female western marsh harriers on the Internet, I noticed that some females have the underside of their wings completely dark and plain, while others have dark underside wing covert feathers (shoulders) and light remiges. The latter are therefore similar to common buzzards. So here is the question: what does the color of the underside of the remiges depend on, and how to distinguish those females with lighter remiges from common buzzards?
First photo: Female with light remiges and dark shoulders
Second photo: Female with completely dark underside of the wings
(These are not my photos, the first photo is from polish Wikipedia and the second one is from eBird - western marsh harrier, made by Albin Jacob)

 

[Farnboro John]

Looking through photos of female western marsh harriers on the Internet, I noticed that some females have the underside of their wings completely dark and plain, while others have dark underside wing covert feathers (shoulders) and light remiges. The latter are therefore similar to common buzzards. So here is the question: what does the color of the underside of the remiges depend on, and how to distinguish those females with lighter remiges from common buzzards?
First photo: Female with light remiges and dark shoulders
Second photo: Female with completely dark underside of the wings
(These are not my photos, the first photo is from polish Wikipedia and the second one is from eBird - western marsh harrier, made by Albin Jacob)

They aren't particularly similar to Common Buzzards which have barred tails that are shorter and wider, with straighter wider planks of wings. Structure will serve you better than colour especially as you will often see birds as silhouettes against the sky.

John

 

[TheBlackGrouse]

Agree with Farnboro John, the shape, the proportions are very imprortant. And of course the flight. Besides, the plumage of Marsh Harriers is extremely variable and adults may have parts of immature birds. The identification can be difficult when they are migrating. Then they may fly at high altitude in a straight line. But even then, try to look at the tail, the shape, the head. Last year, at the coast (cloudy), a Marsh Harrier was coming from England at an altitude of about 1 kilometer. Many experienced birders there and it was quiet for a while, they had no clue. You don't expect this species there, it was funny to see the reactions once they found out it was 'just' a Marsh Harrier.

 

[JayFeatherPL]

They aren't particularly similar to Common Buzzards which have barred tails that are shorter and wider, with straighter wider planks of wings. Structure will serve you better than colour especially as you will often see birds as silhouettes against the sky.

John

Agree with Farnboro John, the shape, the proportions are very imprortant. And of course the flight. Besides, the plumage of Marsh Harriers is extremely variable and adults may have parts of immature birds. The identification can be difficult when they are migrating. Then they may fly at high altitude in a straight line. But even then, try to look at the tail, the shape, the head. Last year, at the coast (cloudy), a Marsh Harrier was coming from England at an altitude of about 1 kilometer. Many experienced birders there and it was quiet for a while, they had no clue. You don't expect this species there, it was funny to see the reactions once they found out it was 'just' a Marsh Harrier.

Do you often see the colours of a flying bird of prey?

 

[TheBlackGrouse]

Do you often see the colours of a flying bird of prey?

Often you can see the color of a Marsh Harrier when it is flying just above the reed. Seeing the colors depends on altitude, distance, the sun. Sometimes everything is visible when a bird is 800 meters high in the air, sometimes it's just a silhouette even though the bird is close. Most of the times you only see a few parts of the plumage.

Overall, I rely more on size, shape, speed and flight than on colors. For raptors I have a certain spot where I watch them for hours regularly. This way your size and speed estimations become better and better. Since you are familiar with the shape and flight of the local raptors at 500 meters, 1 km etc. you have a better chance to identify a new one. At my spot Kestrels and Buzzards are always present, Marsh Harriers too, sometimes even in the winter, so I have some good benchmarks

 

[JayFeatherPL]

They aren't particularly similar to Common Buzzards which have barred tails that are shorter and wider, with straighter wider planks of wings. Structure will serve you better than colour especially as you will often see birds as silhouettes against the sky.

John

Wait, so which bird has straight, plank-like wings? Because I thought it is western marsh harrier, that has straighter wings.

 

[Richard D]

Wait, so which bird has straight, plank-like wings? Because I thought it is western marsh harrier, that has straighter wings.

Buzzards have rounder wing tips and broader (from front to back) wings. Harriers are slightly more swept back.

 

[Farnboro John]

Wait, so which bird has straight, plank-like wings? Because I thought it is western marsh harrier, that has straighter wings.

Its also a question of proportion: Marsh Harrier has more tail, so at a distance a Buzzard, especially with its tail spread, merges into a broad blob while Marsh Harrier retains the visible tail. Both frequently soar with wings held in a V.

John

 

[TheBlackGrouse]

Its also a question of proportion: Marsh Harrier has more tail, so at a distance a Buzzard, especially with its tail spread, merges into a broad blob while Marsh Harrier retains the visible tail. Both frequently soar with wings held in a V.

John

That's a good description of an important field characteristic! Yes, a soaring Buzzard merges into a broad blob while a Marsh Harrier still makes a slim impression (tail and wings). The same applies to White-tailed and Golden Eagle. At least half of my raptors are identified by field criteria like this because they are too far away to see the colors. It gets even better when you have to deal with Common and Honey Buzzard (summer), Common and Rough-legged Buzzard (winter), watching raptors is addictive

 

[JayFeatherPL]

Often you can see the color of a Marsh Harrier when it is flying just above the reed. Seeing the colors depends on altitude, distance, the sun. Sometimes everything is visible when a bird is 800 meters high in the air, sometimes it's just a silhouette even though the bird is close. Most of the times you only see a few parts of the plumage.

Overall, I rely more on size, shape, speed and flight than on colors. For raptors I have a certain spot where I watch them for hours regularly. This way your size and speed estimations become better and better. Since you are familiar with the shape and flight of the local raptors at 500 meters, 1 km etc. you have a better chance to identify a new one. At my spot Kestrels and Buzzards are always present, Marsh Harriers too, sometimes even in the winter, so I have some good benchmarks

I thought that you just have to wait long enough and the bird will fly against the clear sky, so you can easily see it's colours, because identifying by the silhouette itself can be really difficult.

 

[Farnboro John]

I thought that you just have to wait long enough and the bird will fly against the clear sky, so you can easily see it's colours, because identifying by the silhouette itself can be really difficult.

Clear sky is not inevitable in Northern Europe and birds against grey are normally silhouettes.

John

 

[JayFeatherPL]

Okay, but the size of the bird can be really tricky, because you can't estimate the size, if you don't have a proper reference and the birds can fly on the different heights; the birds flying lower look bigger and the birds flying higher look smaller, so for example the golden eagle flying high can look as big as a buzzard (even the Collins Bird Guide says so).

 

[Farnboro John]

Okay, but the size of the bird can be really tricky, because you can't estimate the size, if you don't have a proper reference and the birds can fly on the different heights; the birds flying lower look bigger and the birds flying higher look smaller, so for example the golden eagle flying high can look as big as a buzzard (even the Collins Bird Guide says so).

That's why you need to learn structure more than plumage.

John

 

[JayFeatherPL]

That's why you need to learn structure more than plumage.

John

Okay, so can you tell me how I can identify these birds by the silhouette?
Black kite and spotted eagles (both have plank-like wings and hold their wings horizontally with a decurved primaries)
Golden eagle and common buzzard (both have broad and rounded wings and the rear edge of the wing has an „S” shape)
Golden eagle and honey buzzard (both have broad and rounded wings and the rear edge of the wing has an „S” shape + they both have big, rounded heads)
Common buzzard and rough-legged buzzard (their silhouette looks almost the same)
Harriers and spotted eagles (both have plank-like wings)
Black kite and harriers (both have plank-like wings)

And is the position of the wings in the flight a good way to identify a raptor (wings held horizontally or in a "V")?

 

[01101001]

Not sure if it helps, but maybe it will. I enjoy these plates anyway (all pictures clickable).

https://www.acopiancenter.am/plate10.asp

Plate 13 - Buzzards, Kites and Osprey - A Field Guide to Birds of Armenia ::Acopian Center for the Environment

https://www.acopiancenter.am/plate14.asp

Plate 15 - Sparrowhawks, Goshawks, Kestrels, Falcons, Merlins and Hobbys - A Field Guide to Birds of Armenia ::Acopian Center for the Environment

 

[johnallcock]

Looking through photos of female western marsh harriers on the Internet, I noticed that some females have the underside of their wings completely dark and plain, while others have dark underside wing covert feathers (shoulders) and light remiges. The latter are therefore similar to common buzzards. So here is the question: what does the color of the underside of the remiges depend on, and how to distinguish those females with lighter remiges from common buzzards?
First photo: Female with light remiges and dark shoulders
Second photo: Female with completely dark underside of the wings
(These are not my photos, the first photo is from polish Wikipedia and the second one is from eBird - western marsh harrier, made by Albin Jacob)

Going back to the original question about why some birds appear to have paler remiges than others.

One of the factors that can affect the apparent wing pattern is the lighting on the photo. In the first photo you shared, the bird is banking and catching the sunlight on the underside of the wings. The flight feathers are reflecting back the light, making them appear paler. The underwing coverts have a different structure and do not reflect light so much.

On the second photo, the underwing is in shadow and the flight feathers do not catch the light in the same way, but if this bird were to change position I think it would be closer to the first photo. Buzzards have paler flight feathers, so always appear pale, even when in shadow.

This is one reason why people on the ID part of the forum will often ask for more photos of a bird - the same individual can look different depending on the viewing conditions and a single photo can be misleading.

 

[TheBlackGrouse]

Okay, so can you tell me how I can identify these birds by the silhouette?
Black kite and spotted eagles (both have plank-like wings and hold their wings horizontally with a decurved primaries)
Golden eagle and common buzzard (both have broad and rounded wings and the rear edge of the wing has an „S” shape)
Golden eagle and honey buzzard (both have broad and rounded wings and the rear edge of the wing has an „S” shape + they both have big, rounded heads)
Common buzzard and rough-legged buzzard (their silhouette looks almost the same)
Harriers and spotted eagles (both have plank-like wings)
Black kite and harriers (both have plank-like wings)

And is the position of the wings in the flight a good way to identify a raptor (wings held horizontally or in a "V")?

In order to prevent a very long reaction, I'll give an example:

The Common Buzzard and Honey Buzzard have more or less the same size and colors. Both are present in the summer in the same habitats. Normally the differences in proportions (different wing, head, long rounded tail etc.) are visible but juvenile Honey Buzzards and small adult males may look similar to Common Buzzards over a long distance. Then you see a Buzzard and you see the flight. The Common Buzzard has stiff wings, like a plank, the wings of a Honey Buzzard look elastic/flexible, giving a relaxed flight. Another useful characteristic: Honey Buzzards have flat wings when soaring while Common Buzzards raise their wings a little. Besides, Honey Buzzards rotate their tails often. When soaring a Common Buzzard looks like an amateur. Ok it stays in the air but already struggles with a little wind. A Honey Buzzard has much more 'control', has smooth movements. Over the years you get a feel for that.

Sometimes the smaller male Honey Buzzard has fast stiff wing beats. That can be misleading, then the flat wings are important and try to get some information about the head and tail. This is not a complete overview, it's just a start.