Semi Arid Grassland

About an hour's drive southeast of Tucson there is a beautiful grassland community known as the Las Cienegas National Conservation Area. It is on the edge of the Sonoran desert, and is an area of gentle rolling hills. Mesquite tress have been invading the grassland, and the BLM has tried to remove the trees by controlled burns, and mechanically removing them with bulldozers. One of my friends Danielle, has been looking at how these methods affect the small mammal populations in the grasslands. I had the chance to help Danielle and her friend Eric during one day of their work. One of the rodents caught in a live trap Danielle, and Eric set. In each plot there were 100 traps set, and in many of the plots over 90% of the traps had animals in them when we checked. The traps are baited with bird seed and checked early the next day. Any captured animals are identified, and sometimes measured and marked, then released where they were caught. Kangaroo rats are especially adapted to dry conditions in that they never have to drink. They get all the water they need from the seeds they eat. Their kidneys are much better at conserving water than those in other mammals such as humans. One kangaroo rat built this mound and the paths leading to it. A bit of care must be taken when handling the animals as they will bite!

At The Mammoth Hot Springs Visitor Center- Yellowstone

Here is another group of savvy elk. The irrigated lawns around the visitor center at one of the lower elevations in the park provide very nutritious food long after the other grasses have dried up and pulled nutrients back into their roots. The lawns have been in existence at this visitor center since the early 1900’s when they were planted by the Army. Soldiers were the first park rangers when Yellowstone was established, and this area was known as Fort Yellowstone. The soil is high in silica and was so irritating to the lungs of the soldiers, grass was planted to relieve the lung problems. While the elk that feed on the grasses go into the winter in better shape than other herds, all of the visitors in the area cause a nightmare for the park rangers. The bull elk is very protective of his herd and can attack people who get in between him and the females. One year a bull took out the back windows of five different parked cars. I guess he couldn’t understand why the elk in the window would not back down when he went through all the aggressive postures. Finally he attacked it and it went away, only to reappear in the next car’s window….and so on.
There are signs such as this one up all over, and a whole crew of rangers who try and keep people away from the bull elk especially. However some people just ignore the signs.

At the Hot Springs

These ladies are no fools, they and their calves are lounging where it is nice and warm. After all, where would you want to hang out when the temperature drops? That’s right at the hot springs. What better place to sit around and chew your cud? But where are the boys? Well, with this group there is only one boy and he is busy making sure no others come around because September is the middle of the elk rut. During the rut male elk guard their group of females to prevent other males from mating with the females. This is an exhausting time of the year for the males. They don't sleep or eat during most of the rut. For about a half an hour before I took these pictures, I could here the male bugling and finally he stepped out from behind the trees.
Female elk ovulate in response to a variety of stimuli such as hearing the male bugle, and seeing and smelling him. Males also bugle to announce their presence to other males in the area.

Back to the Tetons

The Teton mountain range is spectacular, as is the wildlife in the park. The snake river runs through part of the park, and provides habitat for a host of animals like moose and river otters! I saw four otters one morning, and four moose while in the park. There was also a female grizzly bear around the Jackson Lake lodge with two cubs, but I never saw her. It rained and hailed while I was in the park, but cleared up usually by mid-day.

Galapagos Sea Lions

&uot&

The sea lion is one of the animals one first notices in the Galapagos. The young ones are especially curious and playful. They often approached us when we were snorkeling, and pulled at our fins. On one occasion a pup bit several people in the class while we were swimming. This endemic seal lion is most closely related to the California sea lion. The Galapagos sea lion is smaller than the California sea lion, but males can still weight as much as 250 kilograms (550 pounds). Females are smaller, and by comparing the photos below, you should be able to see other obvious differences.

Sea lions eat fish and squid, and may travel far out to sea to hunt. Sea lions also spend a good amount of time resting on sandy beaches.
Females typically give birth to one pup, and may still be caring for an older pup when the newest is born. There is competition between the two, and sometimes the younger one dies.
Sea lions breed annually, but gestation is only 9 months. Implantation of the fertilized egg in the uterus is delayed. About three weeks after giving birth, the female is ready to breed again, but the fertilized egg only divides a few times, then stops development and does not implant in the uterus for two months or so.
Female sea lions live about 20 years, and males a bit less. Males compete with each other for sandy beach territories, and the beach master does not feed while defending his territory. Because of this, any given male is not a beach master for longer than a couple of months. Compare the female in the picture above, with the male below. What differences do you see?

The beach master mates with the females that choose to use his beach, but females are free to move from his territory to another if they find him unsuitable. Males are much more aggressive than the females and defend their territories vigorously by first barking above and below the water. I was warned away from a territory in this manner while snorkeling and quickly swam away. No need to argue with a 500 pound animal.:)
El Nino events have had a negative impact on the populations of Galapagos sea lions. During the El Nino event of 1997-98 their population numbers feel 48%. Some simply left, but there was also high mortality. 90% of those born in 1997 died, and 67% of the dominant males died of starvation. In 1979 there were about 50,000 sea lions in the Galapagos. A survey done in 2001, found an estimated 14,000-16,000 animals. Since then some recovery has occurred, with a more recent survey finding an estimated 16,000-18,000.
For more information about sea lions, and other Galapagos organisms you can visit the website of the Darwin Foundation at: http://www.darwinfoundation.org/