Dear Darasingh;

I think that you are providing the answer in your question; if you deal with snake species that do not show a visible sexual dimorphism, then the answer is: no, you won’t be able to know the sex without catching the individual. Some species do show sexual dimorphism, more or less visible, like different body proportions (thicker tail base, etc.) or color (look for example at the recent description of the pitviper Trimeresurus phuketensis, available on RG, where males and females show different coloration), etc. But what is your main reason for not catching the snake to check its sex? If you intend to perform a study where it is important to know the sex of each individual, then you should definitely work on a species with an apparent sexual dimorphism or catch the individuals. I would also like to stress that in tropical areas where snake diversity is high, with similar looking species living in syntopy, not catching the individuals might also lead to species misidentifications.

@Oivire Pauwels sir, Thanks for the response.

My intention behind not catching snake is that animals have to go through immense stress during catching and handling. So, if I can do work without handling them, I'd prefer not to.

Secondly, in India snake catching and handling rules are so strict. Every time we catch a snake a forest department official have to accompany us.

When it come to identification, a quality photograph proves to be handy most of the time.

But, looks like I cant work on their sex ratio without handling them.

This article may be helpful

Article Stumpy tail: A clue for sex identification in certain reptiles

DSingh first I would like to know do you think the snakes stay till you find out their sex and are you that dare enough to stand and examine the SSD (snake sexual dimorphism). Anyway it may be difficult to say the moment you see the snakes unless otherwise you are an expert. Seems the length of snakes male vs female vary (studied in Reptilia II Inter). used to hear the snakes release pheromones (scent) especially elder people used to say stories and read in novels also that cobras of special type (females) release nice sandalwood smell (devtah samp). check the following points as well as links, attached articles and photos too.

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Visual Clues

Since the sex organs are held internally, sexing visually is difficult, but there are visible clues. Because of the presence of the hemipenes, these visual clues relate to the shape and lenght of the tail:

Male: tail thicker and longer than in females, and also tapers less evenly to the tip (thicker for a bit then suddenly thinning).

Females: tail thinner and shorter than in males, and tapers smoothly, evenly and more quickly.

While the differences can be fairly notable when comparing snakes, it is more difficult if you don't have males and females side by side.

http://www.herpo.com/sexing/

http://vpi.com/publications/determining_the_sex_of_snakes

Images of male snake

Thanks @Jetty ma'm for the links.

Dear Darasingh,

The visual clues given above (by Ms. Jetty) are pretty accurate for sexing snakes in situ. You should also watch for some species-specific traits - in some species females tend to be considerably larger than males, while it is opposite in some other species. It can be coupled with some behavioral traits - ritual male fights in species with male-biased sexual dimorphism, or mating balls in species with female-biased sexual dimorphism, etc. These are all useful clues worth observing, especially if you need to avoid handling snakes.

You can also focus your study on species with pronounced secondary sexual characteristics (color, pattern) which can be sexed by visual inspection on the spot.

On the other hand, if the sex ratio is important for your study, I think you should obtain permit for catching and handling snakes in order to sex them accurately, because most times you won't be able to do that in the field without handling or disturbing the animal. Bear in mind that you will need to handle the animal quite short, less than for measuring or taking DNA samples, for instance. Snake sexing is not invasive and, if handled correctly, the risk of prolonged stress or injure for the snake and the handler are minimal (always have trained and experienced handler for venomous snakes or large constrictors). Now, I know that procedures for obtaining permits can be difficult in most countries. You will most likely need to specify localities in which you will do your study and the species you will study. The need for a local official to accompany you on the trip can also make organization more complicated.

@Vaithianathan Kannan sir, thanks for suggestio. I have ordered the book.

@Aleksandar Urošević sir, thanks for your valued and informative response. Actually I have got permissions but, the presence of official is a compulsion, as many snake smuggling cases have been reported from the region. This is why I am looking for alternatives.