Rocky Mountain Bighorn Sheep

1. Engage students by using the bighorn sheep critter box that can be checked out by contacting the Information and Education Division at NM Department of Game and Fish, 505-476-8095. This box has a ram skull with curled horns.

The difference between antlers and horns: Antlers, on members of the deer family, are grown as an extension of the animal’s skull. They are true bone and are a single structure found only on males. Antlers are shed and regrown each year. Horns, found on pronghorn, bison and bighorn sheep are two-part structures. An interior of bone (an extension of the skull) is covered by an exterior sheath grown by specialized hair follicles. Human fingernails and the exterior of horns are made of a similar material, known as keratin. With the exception of pronghorn, horns are never shed and they continue to grow throughout an animal’s life. Pronghorn shed and regrow horn sheaths each year. Rams can be aged by counting the rings on their horns. The first ring forms at age 1 ½ years.

2. Engage further by going to the NM Department of Game and Fish web site. Click on the Conservation tab at the top of the opening page. Open page for Bighorn Sheep Management (Conservation -> New Mexico Wildlife Species -> Mammals -> Bighorn sheep). This page has a color photo of large rams above treeline. Click the following PDF’s for identification and photo gallery (Bighorn – Ewes – Rams Identification Guide and Bighorn – Ewes – Rams Photo Gallery) . Either print this page for students or have students open on their devices. The photos have captions explaining how to identify ewes (females) from rams (males). These are all young animals. Note small horns compared to opening page image of large adults with curled horns.

3. Ask students to do a Quick Writes (see Extension tab) on everything they know about Rocky Mountain bighorn sheep and/or any words that come to mind after exploring the critter box and after looking at photos from step 2.

4. Create a KWL list using student information from step 2. Save list and create another at end of lesson to assess how much students learned.

5. Students read Wildlife Note: Rocky Mountain Bighorn Sheep (This Wildlife Note is located under Education -> Conservation Education -> Educational Materials. Any advanced vocabulary definitions can be found in the Curriculum’s Glossary).

6. Arrange desks in large circle, seminar style for group discussion.  Seminar style is large circle with everyone facing the group. Teacher sits within circle and can move at random, as needed for management purposes and to teach this style of group discussion.

1. Read Wildlife Note out loud (teacher decides how much one person reads) and go around circle reading and charting new vocabulary words in science notebooks. Teacher may want to list on white board or project list from a laptop.
2. As a whole class, discuss natural history of Rocky Mountain bighorn sheep, using categories on Wildlife Note-range, habitat, description, behavior, diet, reproduction and conservation. Click here to see photos from a bighorn sheep trap and transplant operation.
3. Allow class time for defining new words. Many words are used in sophisticated ways that may be unfamiliar to students. Teacher will need to facilitate vocabulary discussion and understanding for each section of Wildlife Note. Students may want to try making picture grams as definitions. For example, the word extirpated in the first paragraph could be drawn as a plant being dug up by its roots. One definition for extirpated is “rooted out.”  The Rocky Mountain bighorn sheep did not become extinct, but their populations were reduced dramatically by the Westward expansion of the U.S. in the 1800’s and early 1900’s. 
4. Ask students to do a Quick Write after reading each section and after discussing vocabulary. Students may also create graphic organizer to write reflections and understanding thus far.
5. To facilitate discussions and to assist students in learning how to talk, listen and ask questions, use the Bounce Card that is referred to in materials and is reproduced here with this lesson.
6. Teacher periodically checks that Quick Writes have been completed throughout the activity.
7. Questions to check for understanding, based on Wildlife Note:
   • What were three causes for the decrease in Rocky Mountain bighorn sheep?
   • After several failed attempts at reintroducing these bighorn sheep, what prohibition allowed the Rocky Mountain bighorn sheep to successfully establish in the Pecos Wilderness, wheeler Peak Wilderness and Latir Peak Wilderness?
   • Describe the physical characteristics that are different between the rams and the ewes.

7. Using the Rocky Mountain Bighorn Population Trends, find the population counts from 2003 to 2013 in table and graph formats.  Print and make copies for students.  Students should be able to explain the simple line graph for total population numbers from the chart. Click here to see map of NM and Rocky Mountain bighorn sheep habitat locations.

8. Look at numbers for the Pecos Wilderness herd on the chart. Students should notice how the population for the Pecos declines starting around 2007 and it drops dramatically by 2010; and then the population numbers increase from 2011 to 2014. Students can make inferences about why the population declined. See first paragraph under the heading Conservation on the Rocky Mountain Bighorn Sheep Wildlife Note. Students may infer:

1. Some animals got sick or starved.
2. Not enough predators in the high mountains, so the population got too large and as a consequence the high altitude habitat did not have enough food for all of the herd.
3. The primary predator of Rocky Mountain bighorn sheep is the mountain lion, also called a cougar. In the past, wolves would have preyed on bighorn sheep as well. The wolf is now extirpated from most of New Mexico. The exception is the USFWS reintroduction program for the Mexican wolf. This effort is centered in the southwest part of the state in the Gila Wilderness and locations in neighboring Arizona.

Information from Department biologists: Several years of heavy snows and hard winters caused animals to starve. As the habitat recovered, the population rebounded and began to grow again. This is an important concept known as carrying capacity .

9. Students draw a line graph similar to the example on the handout, for another region’s bighorn sheep population from 2003-2014.

1. Note areas where there were no sheep for some years, Dry Cimarron and Rio Grande Gorge. The chart shows a small population for each area (2006, 2007) that is due to those animals being moved there from elsewhere by the Department. Periodically there are “sheep traps” where sheep are trapped in an over populated region and moved to new regions in the state.
2. Using chart showing transplant history going back to 1940. Note on chart the release site column and the years that the bighorn sheep were introduced starting the populations for Dry Cimarron and for the Rio Grande Gorge. Both of these sites had a zero population prior to this trapping and relocating event. This information corresponds to the numbers on the chart that students are using for population trends.