All images taken at our behavioral arena site in the Mysore Zoo. Special thanks to the zoo administration and staff for their wonderful help!
by Shannon – This weekend I had the honor of observing the research of NCBS graduate student, Jyothi Nair, a member of Uma Ramakrishnan’s lab and honorary NICE lab member. Jyothi, Uma, and I have been working together on an exciting project for the past 3 years: Do female Indian blackbuck use olfactory cues to identify suitable mates?
Blackbuck, Antilope cervicapra, or the Indian antelope, is unique for multiple reasons. First, it is the sole living member of its genus, and lives in grass – and scrub-lands across India. Second, during mating season the males exhibit a behavior that is rare in mammals: Lek mating behavior.
A Lek, which is the Swedish word for play, denotes a specific type of mating system where one of the sexes (generally males), gather in specific territories within range of each other and display and compete for the opposite sex. You can think of it like a date auction of sorts, which was (bizarrely) really popular in 80s America when I was growing up:
Blackbuck also does this. Males form large ellipsoidal leks with only the males in the center “getting the girls”. All season the males fight each other for the prime “center spots”. They mark their territory with urine and dung constantly to let everyone know who claimed that spot. However, it has not been clear how females know where the center is. These leks are sometime hundreds of meters wide in very flat areas, and the center is not necessarily the geographic center. So how do females know how to find the best males?
In the deserts of Rajasthan, Jyothi has observed that females, upon entering the lek (or starting the auction as it were), sniff their way around – constantly sampling territories of various males. For the past two years, she has been sampling the dung piles created by the lekking males and comparing the central males with the peripheral males. Basically, she’s assessing the olfactory version of the Tinder swipe. But what makes female blackbucks swipe right?
Jyothi used a complicated multivariate analysis to assess hundreds of volatiles from the dung piles, and selected a subset that seemed to correlate with mating success. Now comes the hard part – how do we know these chemicals play a role?
Enter the Zoo. The lovely Mysore Zoo, a 125 year old zoo about 3 hours drive from Bangalore, has a wonderful group of about 40 blackbucks. After obtaining the proper permissions, the zoo staff have helped us to create “artificial dung piles” where we spray our test dung or control odors on the soil and observe whether blackbuck females inspect them.
Left: Zoo Staff spraying our test odors in a random quadrant setup. Top Right: Our “perfumes”. Bottom Right: Sampling soil after spraying for chemical analysis
And guess what? They are! We’re not sure if the chemicals we’ve identified are significantly attractive yet (we are still in the middle of testing), but the experiment is definitely working. Each day Jyothi has several females and some males come and inspect our test odors. So, perhaps we will be able to create our Eau de Blackbuck parfum soon!
Females sampling our test odors