Photo © Keith Williams

October 2012 News

The Sweet Life of Barn Owls

Down in the sugarcane fields of the Everglades Agricultural Area (EAA), Barn Owls are just beginning their fall nesting attempts. Here, Barn Owl densities are among the highest in the world, and a thriving nest box program is partially responsible for this success. We asked Dr. Richard Raid of the Everglades Research and Education Center, University of Florida (Belle Glade), just what makes life so sweet for Barn Owls in the EAA. According to Dr. Raid, during most of the year rodents that live in the sugarcane fields provide the owls with an almost unlimited source of food. These rodents can cause massive damage to crops, so the owls help growers by removing some of these pests. The owls can raise two broods per year, corresponding with the cycles of sugarcane harvest. With the owls’ unusually large brood size of 4-8 chicks per nesting attempt, and each chick capable of eating one and a half times its weight in prey per day, it’s easy to see why growers might be sweet on these handsome owls.

If you would like to encourage Barn Owls to nest in your area, Dr. Raid offers some suggestions. First, start by putting up a Barn Owl nesting box in appropriate open habitat (i.e., sparse trees, low vegetation). You can mount it in a barn or silo, ideally in a structure with at least two exit routes. You can also mount it on an 8-10′ free-standing pole, preferably facing north to reduce the amount of daylight in the box. To sweeten the deal, add a predator guard to the pole. Nest boxes will be colonized more rapidly if placed in areas with existing owl populations, so if you don’t live in a rural area, talk to a local farmer or rancher about maintaining a box on their land. Finally, prevent bees and wasps from colonizing the box by applying a thin layer of bar soap on the inside surface of the roof. You can help us track the nesting success of Barn Owls by registering your boxes and monitoring nests with NestWatch.

NestWatch Data in Action: Studying Hybridization in Titmice

Where the ranges of two closely related bird species overlap, individuals of each distinct species sometimes interbreed and produce hybrid offspring that are a mixture of both. Claire Curry (Ph.D. candidate, University of Oklahoma, Norman) is studying this phenomenon in Tufted and Black-crested titmice in Texas and Oklahoma to determine what exactly it is about the biology of these two species that enables them to interbreed and why this interbreeding results in a distinct zone where hybrid titmice occur.

“The titmouse system is great for studying the process of hybridization because there is an older hybrid zone in Texas, where the two forms have been interbreeding for thousands of years, while in southwestern Oklahoma the Black-crested Titmice have only recently arrived within the past 100 years following the expansion of mesquite trees due to fire suppression and overgrazing,” explains Curry. “I’ll be using NestWatch data to test if the two distinct species and their hybrids differ in their nesting success. This measure of evolutionary fitness is important to help distinguish among several theoretical models of why hybrid zones exist. Data gathered by NestWatchers will be an important piece of the puzzle when I combine it with behavioral data that I have also gathered.”

Wondering if you have seen a hybrid titmouse? Here’s what to look for. Hybrids in Texas are only found in a narrow strip about 25-30 miles wide that stretches from the Gulf Coast northward through Austin and past the western side of Fort Worth, and then extends to the west at the Red River. In Oklahoma, hybrids are only found in the extreme southwestern corner of the state from just west of the Wichita Mountains northwestward to the Texas panhandle. Crest color of hybrid titmice ranges from gray to jet black. The foreheads of hybrids typically are brown or chestnut, while Tufted Titmice have black foreheads and Black-crested Titmice have pale foreheads. Identification of hybrids is especially difficult at the edges of the hybrid zone because their plumage looks closer to that of the adjacent distinct species.

Fall Challenge Update

Have you participated in our Fall Classic Challenge yet? Win great prizes by predicting which states will reign supreme when it comes to entering data for some of America’s favorite nesting birds. Each week on our Facebook page, we’re posting a new bird species along with the current top five states reporting that species. Look at the data entry stats for each week’s species on our home page, then make your predictions for which five states will be on top at the end of the year using the voting link provided in the Facebook post. One point will be awarded for each correct rank. On December 14, final tallies of nesting attempts entered in 2012 will be calculated for each state, and the person with the most correct rankings will win a free Cavity-nesting Birds poster, Common Nesting Birds poster, and a Bluebirds Inside the Nest Box DVD. Be sure to enter your nesting data soon, because you may just tip the balance. Visit us on Facebook today to vote for Week Six’s challenge: the Black-capped Chickadee.

Glad You Asked

Some NestWatchers are curious about seeing the “bigger picture” when it comes to nesting birds. If you’ve been wondering where birds are nesting throughout the country, or just in your state, then you’re in luck. We’re pleased to announce the addition of the NestWatch Map Room to our website. With this new feature, you can explore nest sites submitted to our database for any species in any year. Wondering if your nest record is a first for your state? Or simply interested in finding out how many nest sites are currently in our database? This is your interactive space for exploring the NestWatch database. Go ahead and try it, and please send us your feedback.

Monthly Winner

At the beginning of each month, NestWatch randomly selects one participant who has entered data that month to receive a copy of the NestWatch Common Nesting Birds of North America poster. This month’s lucky winner is Sarah Koval. Congratulations, Sarah!

Cornell Lab of Ornithology

Cornell Lab of Ornithology