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An Update From the Zoo's Lion Keepers
September 2009
New Roof
This year we were lucky enough to receive money needed to replace the cracked and leaky roof and the skylights at the lion house, and refurbish the water moats. The construction crew has already started and the work will continue through November. During this time, we will only have two of our three cat yards open for viewing at a time.
What does this mean for our animals, and when visitors can see them? The cats will continue to be available for viewing between 10 a.m. and 4 p.m. The lions and tigers will continue to go outside every day, but time will be limited so that each animal has the opportunity to get some exercise, and maybe a nice cat nap in the sun. We will do our best to have lions in one yard and tigers in the other as often as possible, but occasionally you will find tigers in both yards. Keeper staff will be present during all hours that construction takes place to monitor the cats for signs of stress.
We have decided to hold off on lion introductions until after the construction is done. Please bear with us during this project. In the end, the animals will benefit greatly from having this work done.
Naba and Shera Are Ready for Love
When visiting the lions, you may notice the lionesses exhibiting some silly behaviors, such as rolling around on their backs or playfully mounting their toys. In the wild, lionesses begin breeding around the age of five. When they are ready to breed, they come into estrus, also referred to as a heat cycle. Naba turned five years old last January and comes into heat every couple of weeks. Shera turns five in November and has only come into heat a couple of times. During estrus, Naba and Shera lose interest in food and training, and are difficult to shift outside. They become completely focused on Luke, and demonstrate their desire to meet him by rolling around in front of his door and rubbing their scent all over objects in the yard and indoor dens, signaling to Luke that they are receptive to an approach for breeding.
How does Luke respond? When Luke goes outside, you may see him responding to Naba and Shera’s scents by doing the flehmen response, which looks like a grimace. Luke closes his nostrils and breathes through an open mouth with his upper lip curled back. When breathing this way, Luke uses a special organ, called the Jacobson’s organ (also called a vomeronasal organ) to analyze smells. You may even see him lick urine left behind by the lionesses before you see the flehmen response. By doing this, Luke can learn whether or not that particular female is in heat. Jacobson’s organ is also used to investigate other smells. Other animals, such as elephants, mice, dogs, and even some snakes have this special organ too.
What’s in a Mane?
At the National Zoo, animal care staff and visitors have had the pleasure of watching Luke grow from a one-year-old 186-pound tyke to a 400-plus-pound adult. One of the most pronounced changes over the past three years has been the development of Luke's mane. Male lions are the only felids to develop a mane, which typically begins to grow when the lion reaches one year of age, and will continue to fill in around his head, neck, shoulders, and chest until about the age of four. Luke turns four years old this October and his locks continue to fill in beautifully.
So why does a male lion have a mane? One theory is that the mane’s purpose is to protect the neck during territorial fights with other males. Also, the mane likely plays a role in providing information to other lions. Studies have shown that lions with darker manes are more successful at attracting females, have greater reproductive success, and are more intimidating to other male lions, in comparison to males with lighter colored manes. The development of the mane is related to the male hormone testosterone. A male lion with high levels of testosterone may be more aggressive when defending his territory, and all that comes with it. Testosterone, nutrition, climate, and age are all factors that have been shown to influence the appearance of the mane. High levels of testosterone, good nutrition, cooler climates, and mature age may contribute to a longer and darker mane. To females, this appearance signals good fitness, which will help ensure the survival of her cubs. To males, this appearance signals a tough competitor.
So what does Luke’s mane say about him? Luke’s dark locks suggest that he’s mature (although when you get to know him as we do, you realize he’s still immature and silly in many ways), and eats a nutritionally balanced lion diet. Other male lions may find Luke’s appearance threatening while females probably find him very attractive. Naba and Shera sure do!
Lusaka’s Mass Removal
Earlier this year Lusaka, who is now about 18 years old, developed a mass under the skin on her back. Initially the mass presented as a seroma (harmless pocket of sterile fluid). When we started to notice a slight change in shape of the mass, Zoo veterinarians decided it was best to explore further. A biopsy of the mass determined that it was cancerous. Lusaka was anesthetized by the veterinarians and the mass was removed by outside surgical specialists. After consultation with a veterinary oncologist, follow-up therapy with oral medications to attempt to slow regrowth of the tumor has been initiated.
We are training Lusaka so that the animal health team can collect blood from her tail while awake (unanesthetized) to monitor for any potential side effects. Lusaka is tolerating the treatment very well, and there is no recurrence of the mass as of yet. We are all very pleased at how well she is doing!
