Barn Owl Disaster

Barn Owl Roost Falls

1-P1000076Nine years ago I found a Barn Owl feather lying in the front yard.  Since then I have often seen the owl’s silhouette sitting in trees and sailing silently across the yard.  Four years ago a second feather turned up.  Two years ago, I brushed the spruce tree beside the house and a Barn Owl flapped out.  It perched in a nearby Cottonwood tree and watched nervously while I took the 1-IMG_3088photograph at left.

Last summer a windstorm toppled two of the tall willow trees shading my driveway.  We had seen a Common Barn Owl (Tyto alba) roosting in the thickest tangle of overlapping bra nches between the trees.  It’s been seven months since the trees fell, and I have seen no signs of the owl.

Fallen Trees

About the Barn Owl

Barn OwlBarn Owls are the most widely distributed of all owl species.  They are only absent from Antarctica and the coldest and hottest places elsewhere.  They live on small rodents, and never take anything as large as a house cat or dog.  Barn Owls range from 10″ to 18″ in height.  The one in the picture at left is 15″ from crown to wing tips.  If you have a Barn Owl living nearby, you have probably heard its “shree” call that’s nothing like the hoots and toots of other common owls.

Barn Owls hunt at dusk and during the night.  Though they have excellent nighttime vision, their hearing is so good they can find prey by sound alone.  This lets them detect and capture rodents beneath snow, grass, and brush. The Barn Owl practices elaborate courting and parenting behavior that involves dancing, singing, nest-building and decorating, and surplus food storage.  I recommend the beautifully detailed account of Barn Owl behavior by Anita Albus (2005) .

Barn Owl Benefits

A single Barn Owl family will consume thousands of rodents every year, making the  owl one of the most beneficial predators a farmer can attract.  Rodent control benefits everyone.  We humans are mouse magnets. Our dwellings are like tiny rodent resorts with walls that provide shade and narrow strips of moist soil and vegetation where rainwater collects.  Without owls and other mouse predators, our gardens would become toxic or they would become walled fortresses, and our houses would be besieged in winter by hoards of wild mice looking for a warm bed.

Barn Owl Conservation

Over the past half century, Barn Owls have declined.  Belfries and lofts where owls once nested are now mostly screened and closed (Albus 2005).  The leading causes of the owl decline, however, are the  toxic pesticides in the air, water, and tissues of rodents.  Some people recognize the dangers of pesticides, but heavy use continues in most yards and farms.  The pesticides might do a more thorough job than the owls, but when all the mice and owls are gone, we might find that our produce has lost its flavor.

Barn Owls are nearing extinction in some places (World Owl Trust, Dear Kitty, Doward 2013).  Seven U. S. states recognize the owl is endangered, and this status is spreading.  You might be able to help the owls by developing neighborhood support.  If you can convince your neighbors to drop pesticides, it would be worth your effort to attract a Barn Owl family.   Click here to learn how to invite barn owls to your neighborhood.

Barn Owl References

Albus, A.  2005.  On rare birds.  Lyons Press, Guilford, CN.  276 p.

Arizona Bird Conservation.

Cornell Lab of Ornithology:  http://www.allaboutbirds.org/guide/Barn_Owl/id/ac

Doward, Jamie.  2013.  Battle to save barn owl after freak weather kills thousands.  http://www.theguardian.com/environment/2013/dec/14/barn-owls-threatened-freak-weather

Konig, C., J-H. Becking, F. Weick.  1999.  Owls:  A guide to the owls of the world.  Yale University Press, New Haven, CN.  462 p.

The Owl Pages:  http://www.owlpages.com/owls.php?genus=Tyto&species=alba.

Wikipedia.  http://en.wikipedia.org/wiki/Barn_Owl.

New Arizona Wildlife Notebook

Arizona Wildlife Notebook, Second edition

Arizona Wildlife Notebook CoverI have completed the second edition of the Arizona Wildlife Notebook!  The new Notebook has four more species groups than the first edition, and it has an expanded index.  The most important change is in the conservation status for each species.  This time, I standardized the information so that future changes will be easier to track. Continue reading

Arizona Snakes–Checklist and Conservation Status

By Garry Rogers

Arizona Snake Conservation

Kingsnake

Kingsnake

Snakes form an important element in the flow of energy through Earth’s web of life.  Normally, they help control rodent and amphibian populations while serving as food for larger carnivores.  Things aren’t normal anymore.  Rodent, snake, and carnivore populations are declining and becoming separated by the assault from human activities ranging from habitat destruction for roads and buildings, to direct predation by domestic cats and dogs.  Thus, human activities are severing local and global connections within the web.   The total effect is difficult to predict. Continue reading

Arizona Butterfly and Moth Update–November, 2013

By Garry Rogers

Arizona Butterfly and Moth Conservation

Tiger Swallowtail

Two-tailed Tiger Swallowtail (Papilio multicaudata) Arizona’s butterfly.

Butterflies and moths are pollinators and they are food for other species.  I know of no harm they cause to human interests.  Nevertheless, many die from insecticide poisoning and others decline due to human removal of caterpillar host plants.  The conservation status of these familiar animals is mostly unknown.

Butterflies and moths are not thought of as social insects, but they do interact beyond their feeding and mating behavior.  I have watched two Monarch butterflies perched side by side patiently taking turns at a nectar source, and many of us have seen two or more individuals swirling around with members of their own and other species. Continue reading

Arizona Mammals Update–November 2013

By Garry Rogers

Arizona Mammals

Rock Squirrel on a Fence Post

I always feel closer to mammals than other species groups.  The Rock Squirrel (Spermophilus variegatus) in the photograph is a member of the local colony that lives in the retreating face of eroding lake sediments back of my house.  Though they live in burrows and harvest seeds and fallen fruit, these squirrels are great climbers.  I often see them in the tops of the pear trees picking fresh fruit and the tops of willow trees eating tender buds.  They routinely gather fallen seeds beneath the bird feeders, and it is there that some become nervously tolerant of my presence.

The least skittish of my other neighbors include the raccoons who love to slip in the cat door and eat cat food, the skunks who stroll by brushing my leg in the dark, and the coyotes and deer who often stand and return my stare. Continue reading

Arizona Turtles Update–November, 2013

By Garry Rogers

Arizona Turtles

Turtles have exceptional regenerative powers.  Dr. Justin Congdon, a classmate from long ago, managed a study of turtles in the E. S. George Reserve in Michigan for more than 40 years.  In the 1980’s Justin made a startling discovery:  As they aged, Blanding’s turtles produced more eggs and offspring.  In some ways, the turtles became younger as they aged.  This reversal of reproductive success with age drew global attention from scientists and others interested in longevity and life extension.

Another interesting trait is resistance to toxic materials.  Arizona fish, frogs, and mollusks develop various forms of cancer in response to toxic chemicals in agricultural and urban runoff, and treated waste-water.  Turtles do not.  Like other species groups, however, Arizona turtles suffer from habitat loss and human harvest.

Pond SliderThe pond slider (Trachemys scripta) in the photograph is not an Arizona native.  It probably arrived as a pet sold by the roadside vendor who comes every summer and sells turtles at a highway intersection upstream from my ponds.  There are at least two pond sliders living here.  If humans wouldn’t empty the ponds, the pond slider might live at Coldwater Farm long after I’m gone.

(Just after I wrote the above, a visitor harvesting weeds for his sheep, accidentally backed his truck over the pond slider shown in the photograph, killing it instantly.) Continue reading

Arizona Lizard Update–November, 2013

By Garry Rogers

More than half of the lizard species found in the U. S. are present in Arizona.  They are a colorful group with fascinating life histories.  Lizards help control ants, termites, and other insects, and with only one exception, the Gila Monster, they are not venomous.  Field guides are available online (Arizona Herpetological Association, Brennan, 2008), and in print (Jones and Lovich, 2009, and Stebbins, 1966).

Plateau Fence Lizard

Plateau Fence Lizard

The photograph shows a Plateau Fence Lizard.  These lizards do like fences, but they will sit on any convenient object that gives them an elevated view.  They are found throughout central and northern Arizona.

Lizards are not descended from dinosaurs.  They appeared about the same time and lived with dinosaurs, but they are not closely related.  Lizard legs extend to the sides of the body rather than projecting downward or forward.  Lizards became a separate group in the Late Triassic, over 200 million years ago. Continue reading

Arizona Bat Update–November 2013

By Garry Rogers

Arizona Bat Peril Increases

Big Brown Bat from Smithsonian North American Mammals

The most important change since my last post about Arizona bats is the increased risk of white-nose syndrome.  The disease continues to spread west from its point of introduction on the U. S. Atlantic coast despite research and quarantine efforts.  In September, 2013, researchers confirmed the disease had reached Oklahoma and South Dakota (http://whitenosesyndrome.org/resources/map).

The entities that gain most from
bat extinction are insecticide producers.

Continue reading

Arizona Fish Update–November 2013

By Garry Rogers

Arizona Fish Habitat

A Beautiful Desert Stream Runs Through the Heart of Dewey-Humboldt, Arizona.

Small stretches of the Agua Fria River in central Arizona are perennial. The water is polluted by farm fertilizer and mine tailings. Invasive species are abundant.

The U. S. State of Arizona occupies a dry region with limited precipitation, high evaporation, and not much surface water.  Widespread winter rain and snow, and heavy summer rain can escape evaporation by penetrating the soil and accumulating in fractured rocks and sediments on slopes and in valley floors.  The moisture soaks down slope through the sediments, and appears in springs, intermittent streams, and a few perennial streams and small lakes.  Many isolated endemic and rare species are present in these small moist habitats across the state.  (The header image is a Beautiful Shiner (Cyprinella formosa) photographed by René Reyes of the U. S. Bureau of Reclamation.)

Continue reading

Arizona Grasshoppers and other Singing Insects

By Garry Rogers

Arizona Grasshoppers and other Singing Insects

Grasshoppers, Crickets, and Katydids are familiar to everyone, but there are few records of distribution and conservation status.  This report includes a partial checklist for Arizona grasshoppers.  Grasshoppers are members of the Orthoptera, one of the most familiar insect orders.  Orthoptera includes two suborders: Caelifera (grasshoppers and relatives) and Ensifera (crickets, katydids, and gryllacridoids).

KatydidThe katydid in the photo is probably Greater Angle-wing Katydid (Microcentrum Rhombifolium).  It is common in central Arizona where I live.  According to the BugGuide website, the similar California Angle-wing (Microcentrum californicum) also occurs in central Arizona.  The two are distinguished chiefly by their songs.

Most singing insects are herbivores.  Their occasional population explosions can reduce farm profits, and have led to emphasis on eradication.  Protection deserves more consideration.  Orthoptera are all important biomass recyclers, and all serve as essential sources of food for other animals.  Use of insects for human food is growing in popularity.  As the human population continues to swell, the proportion experiencing the culinary delights of bug dinning will grow.  We have to wait to see if grasshopper ranches arrive before textured soy protein replaces sirloin.

Orthoptera suffer from habitat loss just as other species groups do.  Farms, roads, and buildings are concentrated in valleys near lakes and streams.  The selective destruction of natural habitats in these more productive areas alters the size and composition of insect populations.  These changes reduce ecosystem diversity, stability, and productivity.  The references listed in the Singing Insects of North America website and in the list below are a good place to start to learn more about the ecological importance of these insects.

Grasshoppers

Many of the 400 grasshopper species known to occur in the western U. S. may be present in Arizona, but in the time available to prepare this report I could only verify 59 species from the USDA fact sheets (USDA and Pfadt 2002) and 35 from the Arizona Game and Fish Department (AZGFD–October 2013) website.  The list is almost certainly incomplete, and it probably contains outdated names.

I compiled the list from the range maps on the website of the U. S. Department of Agriculture (USDA), and the October 10 species list by AZGFD.  The USDA fact sheets include maps, photographs, and the natural history of each species.  The Bug Guide provides additional information.

Continue reading