The Monthly Bighorn Report May 2009

Here we provide brief reports about ongoing studies and current events related to bighorn sheep conservation. Please check back frequently!

Yearlings Released into the Wild
On April 10, 2009, the Institute released one yearling ewe and one yearling ram into Tachevah Canyon of the San Jacinto Mountains near Palm Springs. Prior to their release, both yearlings were health tested, fitted with a mortality-sensing expandable radio-collar, and an eartag. The yearlings were flown by helicopter to their release site next to a spring to help ensure they would locate the water there, but also because there is strong fidelity to a release site.

Just five days after the release, the female yearling was observed joining a group of ewes known to reside in Tachevah Canyon. We were ecstatic to see them join up and have since observed her with the same group on multiple occasions. She is doing well and has integrated with wild sheep, which is important for her survival.

Unfortunately, the released yearling ram did not join other sheep and subsequently, his condition deteriorated. He was also hanging out in the flats versus the hillside and was ambushed by coyotes two weeks after the release. We are saddened by this loss, but encouraged by the success of the female yearling. We continue to monitor the released yearling female daily and attempt to observe her weekly.

        
                 The yearling ewe released into the San Jacinto Mountains

Lambing Update:
Bighorn Institute
We are pleased to report that we have had one healthy female lamb born here at the Institute so far this year. She is approximately 6 weeks old, energetic and very playful. There are two more ewes here at the Institute that should give birth this year. They should have their lambs by early June, based on when we had the ram in with them. Ewes have a 6 month gestation period. Since 1985, there have been well over 130 lambs born here at the Institute, many have been released into the wild and have become part of the wild population.

In the Wild
We have documented 3 more lambs in the northern Santa Rosa Mountains (NSRM) since our last update, which brings the number of lambs born up to 27. However, since that time we have also noted that a number of lambs in the wild have disappeared. Lately, we have observed some of the collared ewes and unmarked ewes in the NSRM without their lambs and their udders are drying up, which means they have lost their lambs.

In the San Jacinto Mountains (SJM) we have documented an additional 3 new lambs bringing the total to 5 lambs born this year with a possibility of 4 more ewes that could give birth. We have already seen that one of the collared ewes in this mountain range may have lost her lamb as she has been observed a few times alone. There are only two functioning collared adult ewes in the SJM so it’s very difficult to keep track of the unmarked ewes and their reproductive status. We will continue to monitor the NSRM and SJM herds closely, although 2009 does not appear to be a good year for lamb survival thus far.

Water Sources
As summer approaches and the temperature increases, it gets harder for many animals to find water, including bighorn sheep. There are a few natural sources and as many as 8 man-made water sources available to sheep in the northern Santa Rosa Mountains. During the winter these water sources are not utilized by sheep as much since they can get most of their water needs from vegetation. However, we have recently documented bighorn sheep beginning to utilize these water sources once again. The Institute monitors the man-made guzzlers throughout the year to ensure they function properly. It is especially important during the hot months that the bighorn sheep have standing water available since the vegetation dries up and offers nutrients, but little moisture. There is good year-round natural water available in the San Jacinto Mountains for the bighorn there.

              
                      A man-made guzzler in the northern Santa Rosa Mountains                                          The same guzzler cleaned out by BI biologists
                      covered in algae

 
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