More Male Gatekeepers than Female?

[Shirley Roulston]

I'm sure that someone will know, why are they more male Gatekeepers than female? For every 20 male that I have seen in the past week I have only seen one female. These female's must lay an awful lots of eggs for there to be so many males.

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[Dave McCormick]

Hmm, I know that females always hatch out of pupae a short while after males, so there will be enough males for every female, so more guarentee on mating will occur. I have seen this with Orange-Tip in past. Could be same here with the gatekeepers. Nice shots also

[Pete Eeles]

I think there are a few factors:

1. As Dave says, the males usually emerge earlier and so, depending on where you are in the season for your area, the females may not have emerged in numbers yet.

2. Females are generally less-conspicuous than males and this can translate into their behaviour. This is understandable since they're carrying the precious cargo of the next generation! It is up to the males to find the females, and put themselves at risk in the process, and not vice-versa.

3. A theory, rather than fact - a female larva takes longer to reach adulthood since she is typically the larger of the two sexes (carrying eggs and all!). It therefore takes longer for the larva to reach the pupal stage, and longer for the butterfly to form inside the pupa. There is therefore greater potential for predation in the immature stages of females and so they are, arguably, fewer in number. Complete theory, but it sounds good

Cheers,

- Pete

[Cotswold Cockney]

Plus in just about all species, without exception the males need a few days to feed and become sexually mature before they are able to transfer their spermataphore to the female successfully. At least a week in my experience ~ males that pair prior to becoming sexually mature usually result in infertile ova.

Check that same locality later and you may find the situation changed with more female gatekeepers despite they do tend to have a 'lower profile' than the males which gives the impression that males are more numerous ~ all other things being equal, breed a large brood of butterflies and chances are you'll get a 50-50 sex ratio and it's probably much the same in nature. One 'good' male can successfully pair with more than one female but, to do so, it needs time to feed up and regain its vigor before successful further pairings. Sometimes that very tatty, torn winged male is still very active sexually and still very fertile.... so any really late females need not miss out.
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[Shirley Roulston]

Thank you very much for all that information. This morning my usually walk with the dog along the lane, it was boiling hot and the Gatekeepers were all along the grassy banks, it was too hot to see what sex they were, for once I left them to it, there' a bit like the Walton family as you say good strong parents makes lots children, or whatever you said. Thanks any way. Shirley

[eccles]

Females have only a short period when they are fertile, soon after emergence. At that time they are secretive, requiring the males who have been around for a couple of weeks to search them out. Once they have mated and laid eggs then they can relax, bask and take nectar whilst fending off the odd unlucky male. Having said that, I saw two females do that today, but they nipped off to a bit of grass under a fence to drop an egg or two in the deep grass. So I think the egg laying process is quite protracted after mating.

[eccles]

Further to this topic, the predominance in my area now is of females. This is presumably because many of the earlier emerging males are now dying off, and the females whose egg laying tasks are done can bask and relax more openly.

[Shirley Roulston]

A photo of the two getting together.

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