Saddle-Billed Stork - Male or Female?!

by Stefan Kruger
(White River Mpumalanga South Africa)

Saddle-Billed Stork

Hello to all whom are reading my story.

I run my own safari company doing birding safaris into Kruger National Park & the Mpumalanga Province. I had people with me on one of my safaris into Kruger & we came across this Saddle-Billed Stork, but is it a male of a female?

Look at the photo this bird has both yellow eyes & wattles - the male usually has dark eyes & the yellow wattles & the female yellow eyes with no wattles at all. So I sent the images off to the EWT & they sent it to Dr Alan Kemp for inspection & here is his answer.

Hi Stefan

Have no idea how to interpret Mrs Balls with his/her yellow eyes AND yellow wattles. Have never seen or heard of anything like that in this species, or any other storks, but that may be my ignorance rather than total lack of information. A quick Google search indicates that intersex is regular in all groups of vertebrates (a 1974 book on the subject even), with two main causes, one genetic and the other environmental.

What is interesting, from the Caster Semenya story, is that Limpopo Province has the highest incidence of intersex people in RSA, and one of the highest in the world, and there are doctors studying this and suspecting the DDT is still used to spray round homes for malaria as the cause. Google indicates that several pesticides/chemicals, including DDT, either mimic oestrogens (main female hormones) or despress androgens (main male hormones) and so cause hormonal imbalances during development that can result in various effects, including development of both ovaries and testes. Maybe river/fish quality will indicate if there are any pollutants of these kinds there for concern to the storks - there is probably good river data given the croc problems, and Andrew Deacon may be able to help. Just ideas, but may help in how to proceed, and as always more cases/data will be great.

Am also forwarding you a second email, with images of two subadult SBS taken just above the high level bridge over the Sabie River below Skukuza. This age class was very rare in our early 90s project, so may be of interest. All the adult birds we saw were too far away for useful images.

Ons weet eintlik baie min van hierdie spesie en het op hierdie stadium meer vrae as antwoorde. Ek hou jou op hoogte as jy belang stel.

Tot later

Okay so this bird I found on the S114 between the S118 & S119 Junctions.

I used a canon 400D with a 100 - 400mm F4-5.6 canon lens to take the Images.