Thursday, July 31, 2014

Cubs, Moms, and Fur

An obs session that starts with two little black figures poking out from the den usually means new cubs spotted in the Talek West clan! With new cubs come new tasks for the researchers here at Fisi camp. Not only do we have to identify the mother of the cubs; we also are presented with the task of aging them. The pattern and visibility of spots on a hyena is not only helpful when it comes to identifying an individual but it’s also a great tool for estimating age. With each new cub comes a puzzle, and as researchers we must put the pieces together in order to solve the mysteries of motherhood and age.

Determining the mother of a cub can be a more tedious process than one would think. Since we do not observe the adult females giving birth we use the act of nursing as a “maternity test”. When we see a cub nursing from a female, we can usually conclude that that female is the mother. Although there have been instances of a cub nursing from two different females it has not been observed very often.  This situation however can make this process even more daunting. When a cub is first seen above ground we aim to see the cub nursing a couple of times from the same female to have some certainty of the identity of the mother.

Now onto the subject of aging, when hyenas are first born they are all black and no spots are visible. The age at which we first see a new hyena cub however ranges. Some adult females, especially those who are lower ranking will not bring their cubs to the communal den until they are a couple of months old. The features of a hyena’s fur change significantly within the first few months. In order to age cubs we use a few key characteristics found on their bodies.

Here are a few stages:

A cub that is all black and seen above ground near the den can be 3 to 4 weeks old.

In the next stage, the cubs begin to develop white rings around their eyes, which eventually leads to the development of white eyebrows and faces. The white rings begin to appear at about 4 to 5 weeks old and white eyebrows and faces at 5-6 weeks.

Another section of the body that we use to denote age is the shoulder. Spots begin to emerge on the shoulders at 3- 3 ½ months. The white face is also still present at this stage.

As the hyena cub gets older more spots begin to appear. Instead of just seeing spots on the shoulder there are also spots along its sides and back. The legs of the cubs however may remain black. The fur is also short. If a cub has these characteristics it would be put in the age range of 4-7 months.

At around 8-9 months, the cub’s fur becomes fluffy and long also known as den graduation fur.  The cub begins to molt (the transition from short fur to long fluffy fur). These are some of the last characteristics we use to determine age.  

After determining what stage the hyena is in, we count backwards to determine its birthdate. For example, if it was December 10th and we saw a hyena for the first time with a white face and spots on the shoulder we would count back three months and give it a birthday of October 10th.  Age is not only important in determining the birthdate of a hyena but it also gives us clues as to when a hyena should be graduating the den, dispersing, or having a litter of their own. While new cubs at the den create a new mystery for the researchers solve it also brings excitement and cuteness to the den.

Try and age the hyenas below! Come back to the blog for my next post to see if your estimates were correct.


dee said...

A test ?? Great post, lots of very interesting information, but seriously?? A test?
OK good one Hashlie.

Scissors MacGillicutty said...

First one: spotted all over, except for the lower legs, which are black; also, short fur. That fits your description of the 4 to 7 month old cub.

Second one: Fluffy! (and this is this is when I think spotteds are the cutest) So 8-9 months.

Third one: black with a white eyebrow, and is whitish above the eyes, but there's a band of black running down from the top of its head to its nose. So 5-6 weeks? (this one I'm really not sure of: there's no den in site, so older than 3-4 weeks and its face isn't white, but it's got white rings about the eyes and whitish brows. But are those spots on the shoulders? And I wouldn't call its whole face white; also, at 3 to 3.5 months, unless a cub goes through a big growth spurt just then, it seems much smaller compared to the first cub. So: 5-6 weeks, with the acknowledgment that I could be off because of the spots on the shoulders, but to my untrained eyes, it doesn't seem to have a white face.)

Scissors MacGillicutty said...

PS. Can you/have you sexed the third cub? Or at that age, is it just an exercise in futility?

Michigan State University | College of Natural Science