southern Nevada

This summer (May-July 2010) a few of us from NAU were again working on a project looking at nest predation of open-cup nesting birds in southern Nevada. To study this, we set up videocameras on lots of birds' nests to see which predators came in. Along with this we are analyzing habitat characteristics to see how they might influence nest predation. The birds whose nests we monitored included Willow Flycatchers, Yellow Warblers, Yellow-breasted Chats, and Song Sparrows. We had an emphasis on videotaping the flycatcher nests, since the "Southwestern" subspecies is federally listed as endangered and land managers are interested in which animals are major predators of their nests. We collaborated with a crew from an environmental consulting firm that was monitoring the flycatcher population in the area. Our crews lived in Overton, which is near the north tip of Lake Mead. Here is a photo of a Song Sparrow nest at one of our sites in Mesquite:

One of the factors that may influence nest predation is the amount of canopy cover surrounding the nest. In the watershed of the Virgin River which travels from southern Utah through Nevada, an introduced beetle has been released to combat the spread of tamarisks or salt-cedars, which are an invasive plant species along watersheds in the West. The beetles defoliate the tamarisks over several years until the plants die from using up the remainder of their food stored in their roots and not being able to create more food by photosynthesis without leaves. The concern now is that the defoliation (loss of canopy cover) caused by these beetles may reduce nesting success of the endangered Southwestern Willow Flycatchers by making their nests more visible to predators. On top of this, damming of watersheds has altered the hydrology so much that native willows and cottonwoods will not likely be able to replace the tamarisks once they're dead. Here are some photos showing the progression of the defoliation in the Virgin River Canyon in the far northwestern corner of Arizona this summer:

May 21:

June 24:

 Here is an up-close view of the defoliated trees:

Here are some of these tamarisk leaf beetles (Diorhabda elongata):

Along with the wildlife we were monitoring on our sites this summer, we also saw other cool animals. Here is a photo of a coachwhip snake catching and swallowing a desert spiny lizard:

And here is a shot of a Zone-tailed Hawk at Pahranagat National Wildlife Refuge, one of our primary study sites. A pair of these birds tried nesting here this year. I'm not sure if they were successful in fledging young or not, but if they were successful it would be the first breeding of this species in the state of Nevada. Zone-tailed's are pretty cool in that their overall flight structure and behavior mimics that of Turkey Vultures, allowing them to sneak up on unsuspecting prey.

We also got really close views of a family of Long-eared Owls earlier in the season that had two fledglings. Here is one of the adults:

Here are the two babies:

On a less happy note, there was also a fire at Warm Springs/Moapa (where we lived in the summer of 2009), one of the sites the other crew was monitoring. It burned 600+ acres and destroyed several ranches, and the couple of flycatcher nests there. That day we ended up turned around at a roadblock on our way home, which took us an additional hour or so (it usually took 1.5 hours to drive back from Pahranagat NWR anyways!). From the roadblock I snapped photos:

To give a sense of size, the mounds of green below the tower of fire in the photo are the tops of palm trees:

Of course, the story of this summer wouldn't be complete without mention of how small of a town Overton was. Not having much to speak of in the way of stores or restaurants, the way the community chose to pass the time in the 116 F degree heat was with "Chickenpalooza", an event sponsored by Lynn's Market (a small, over-priced grocery store in town). The event was complete with scavenger hunts and "chicken trivia" inside the store. Yeah small towns! Anyways, we used the event as another excuse to partake of certain beverages as we also did with the 3rd and 4th of July, Canada Day, and at times during the World Cup. Overall, a great summer spent with awesome people.