MONTAGU’S HARRIER

Order: Accipitriformes.
Family: Accipitridae.

39-46 cm

102-116 cm

The adult male Montagu’s Harrier closely resembles that of the Hen Harrier, which also has a white rump but lacks wing bars and streaks on the flank and belly. On the other hand, females and juveniles differ from the Western Marsh Harrier by lacking the characteristic head and throat patch. The female Hen Harrier has a whiter rump and lacks a band just below the covert feathers. The P10 feather ends between P5 and P6. The start of the emargination on P9 is hidden by the primary coverts. Juvenile Hen Harriers have a streaked chest.

Described in the “AGEING” section.

It is possible to recognize 4 different ages in females and 5 in males:

Juvenile specimen: The underparts are ochre and smooth, sometimes with fine dark streaks on the chest. The wing coverts have a border of intense ochre. The secondaries appear dark both above and below. The plumage is new, without molt limits. The male has a gray iris and the undersides of the outer primaries are finely mottled dark. The female has a dark brown iris and the undersides of the outer primaries are barred.

2nd year specimen: The male has a dark yellow iris and a gray-tinged chest. If R1 has been molted, they will be uniformly gray. The wing linings are intensely mottled reddish-brown. The 2nd year female has a dark brown iris and a streaked upper chest but the belly is still juvenile and smooth. If there are molted rectrices, they will be dark brown with bands. Both sexes have all juvenile flight feathers, but in autumn, once molt has begun, there is a mix of adult and juvenile flight feathers.

3rd year specimen: The male is similar to adults but with upperparts and wing coverts of a dull gray with a brownish tint. Sometimes, some juvenile brown feathers are retained on the head or rump. The outer rectrices show wide reddish-brown bars. The lower chest is streaked and lanceolate. The wing coverts have quite a bit of reddish-brown mottling, covering more surface area than in adult males. The 3rd year female frequently appears with a brown or amber iris. The back and head are dark with a similar contrast to juveniles. R1 feathers are browner than gray with faint barring. The outer rectrices have wide, light reddish-brown bars. Wing feathers are quite similar to adult females. The underparts have a light ochre tint with brown striping on the chest.

4th year specimen: Only visible in some males with a slight brown tint on the nape.

Adult specimen: The male has a bright yellow iris. It lacks brown feathers on the nape or rump. The back and wing coverts are uniform ashy gray. The secondaries and inner primaries are gray, while the outer primaries are black. R1 feathers are silvery gray. The outer rectrices have slightly marked bars. The upper chest is gray and smooth, with narrow streaking on the lower chest. The wing linings show lightly marked reddish-brown mottling. On the other hand, the adult female has a yellow iris. The back is light gray-brown, the head is pale and evenly mottled. The primaries and R1 have a distinct gray tint and well-marked barring. On the underside of the feathers, the secondaries exhibit the same pattern as the primaries with well-marked barring. The underparts are light ochre with dark brown striping on the chest.

The Montagu’s Harrier undergoes a complete postnuptial molt that starts in the breeding areas, is suspended during migration, and concludes in the wintering areas. On the other hand, the post-juvenile molt begins in the 1st winter, encompassing body feathers, some wing coverts, and occasionally some rectrices. The first complete molt takes place in the autumn of the 2nd year, coinciding with that of the adults.

Primaries: 10 per wing.
Secundaries: 14 per wing.
Rectrices: 12.