Mugimaki Flycatcher – sexing

posted in: Morphology-Develop., Species | 2

“Seeing so many Mugimaki Flycatchers (Ficedula mugimaki) in one location (8-10) at the seeding bamboo patch offered me the opportunity to try an image adult males, adult females, 1st winter males and females. I find differentiating the 1st winter males and females from each other and from adult females to be quite a challenge. I am not sure all the birds in the OBI database are accurately labelled.

“Gleaning from a number of field guides the following are the key differentiating features:

1. 1st winter males tend to have richer rufous chin and upper breast when compared to adult females. Adult female throat and breast are described as ‘buff-orange’, ‘pale-orange’, ‘tawny-orange’, or just ‘orange’. Having said that I suspect the rufous chest and throat colour come over time and may not be present on ‘arrival’ at migration site.

2. 1st winter males tend to be greyer on the head and mantel when compared to females. Adult females are described as having a grey-brown upperparts.

3. The supercilium or short post-ocular patch is noted to be more prominent in 1st winter males compare to adult females. But some guides say that this only develops when the males are 1st summer and personal observations suggestion is variable. Some guides say the supercilium is not apparent or not present in females but I suspect it is usually present and can be seen if we observe the bird in the right posture and light.

4. Males have a small, short white segment at the outer base of the tail (base of outer rectrices). This is not present in females of any age. This can be very useful in the 1st winter males. But it not that easy a feature to see and can be missed in 1st winter birds. Wells 2007 suggests that occurs only in some 1st winter birds.
5. 1st winter’s are noted to have pointed rather than blunt (adults) tail-feathers tips. Very tough to see in the field but possible in some images.
6. Bare parts of 1st winter birds and adult females are similar (bills brown compared to black in adult males).

“As I work though my own ID I am sharing some images.

“The above, although not a great image, shows clearly the white at the outer base of the tail in an adult male.

“The above is of a 1st winter male that also shows the same feature – white at the outer base of the tail. Note also the clear supercilium and richer rufous upper body colours (richer than a female). Also notice darker beak colour.

“The above is of another 1st winter male as the upper breast and throat are too rich for a female but note that the supercilium is harder to appreciate (could be the posture but I have seen 1st winter males with weak superciliums). Notice much lighter beak this time – ‘horn brown’. Better seen of same bird (below).”

Dato’ Dr Amar-Singh HSS
Ipoh, Perak, Malaysia
28-29th November 2015

Location: Kledang-Sayong Forest Reserve, Ipoh, Perak, Malaysia
Habitat: A ‘damaged’ trail along primary jungle

2 Responses

  1. Daisy O'Neill

    Morning Amar,

    A delightful read over late breakfast on my balcony garden patio after festive tiimes with family.
    Six feet away, a YVBulbul feeds on a ripe mango dropped onto Solartuft balcony heard ‘boong..’ overnight.

    It is always a delight when rare opportunities show difficult bird species where sex of these birds pose challenges and little described. I agree, even OBI do have many images where gender of bird species remain a question mark and few or any at all dare to meet the challenge of imagemasters who painstainkenly have to look and sort out hundreds of images that come through daily.

    Thank you for the opportunity to look these migratories closely to study the differences and share the passion of birds looking DEEP where few have the good fortune to see birds up close near your backyard.

    I wish you many more good opportunities and rare encounters for 2016!

    All Blessings!
    Daisy

  2. Thanks Daisy. Appreciate the comments. Have many more images & hope to look at juvenile females next. Blessings for 2016.
    Amar

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