Elf Owls

Elf owl 3The Elf owl (Micrathene whitneyi) is our smallest owl. Its body size is about the same as a sparrow (5 to 6 inches), but its wingspan is larger (13 to 16 inches).

These owls occur in southern Arizona, the boot-heel of New Mexico, the Big Bend area of Texas, and nearly all of Mexico including the southern tip of Baja. In the winter, Elf owls in the U.S. generally migrate to Mexico.

“The classic image of an Elf Owl looking out of a hole in a Saguaro cactus may be overemphasized. They are abundant in the Saguaro deserts but also are abundant into the mountains reaching elevations of up to about 6000 ft. They can be found in dense mesquite, dry oak woodlands, wooded canyons, sycamores, and probably any other tree within its elevation range. They may be seen in dense scrub and in woodpecker holes in cottonwoods or telephone poles. Classically they are in high desert, foothills, and low in the mountains, and often in dryer habitats.” Source

Elf owls eat spiders, scorpions, beetles, moths, grasshoppers, crickets and other insects. They generally hunt at dawn and dusk. They can catch prey in mid-air or pluck them off tree branches.

Elf owl 2Elf owl 4

Elf owls often nest in abandoned woodpecker holes in saguaro cactus and in natural cavities in upland trees such as sycamores, pines, and walnuts. “Males attract females to potential nest sites by calling from a cavity, then flying out while singing as she approaches. On moonlit nights calling occurs continuously all night. The female selects the nest cavity and begins to roost in it prior to laying eggs to prevent occupation by other hole-nesting birds.” Source “Breeding season in North America is normally May and June (March through August in Mexico). 1 – 5 eggs may be laid but 3 are most common. The incubation period is 21 – 24 days. The young can capture food as soon as they can fly (27-28 days of age) and fledge shortly thereafter (28 – 33 days of age).” Source

The call consists of a variety of soft yelping notes, often running together into a high-pitched chatter. You can hear some sound recordings here.

According to the Arizona-Sonora Desert Museum:

“Elf Owls, like other owls have excellent night vision. They can’t see in complete darkness, but they can see quite well in low-light. They also have excellent hearing. They can catch their prey in complete darkness, by pinpointing it using their ears rather than eyes. Elf owls have “silent flight” which means they don’t make any noise as they approach their prey. The sound of their wing beat is muffled by softened feathers on the leading edges of their wings.” Source

Elf owls are preyed upon by other owls, snakes, coyotes, bobcats and ringtails. Their life span in the wild is 3-6 years. Starlings, which are an introduced bird from Europe, pose a threat to Elf Owls. They take over nest cavities already in use by the Elf Owls, or by other birds according to ASDM. ASDM also notes that in dangerous situations, Elf owls will play dead until all danger has passed.

See many photos here.


The American Beaver in Arizona

Beaver 1Beaver 2

The American beaver (Castor canadensis) is the largest rodent in North America with adults reaching a weight of up to 70 pounds with an average of 40 pounds. (The porcupine is the second largest rodent, see my  article: Porcupines.) The American beaver ranges throughout the U.S. and Canada. It has also been introduced to parts of South America. A different beaver species (Castor fiber) occurs in Eurasia.

Beavers are semi-aquatic mammals that are most active at night. They are excellent swimmers and can stay submerged up to 15 minutes. They have webbed hind feet and a broad, flat tail which propel them through water.

Beavers build “lodges” and dams in lakes and rivers using sticks, stones, grass, and mud. Their structures often have a great (and beneficial) effect on the local ecology.

Beavers eat the leaves, twigs, and inner bark of many tree species. Fermentation by special intestinal microorganisms allows beavers to digest 30 percent of the cellulose they ingest. (source)

Beavers are prized for their fur which consists of long, coarse outer hairs and short, fine inner hairs. The fur has a range of colors but usually is dark brown. Scent glands near the genitals secrete an oily substance known as castoreum, which the beaver uses to waterproof its fur. Beaver meat tastes similar to beef, but care must be taken in preparation to avoid getting the castoreum on the meat. The characteristics of the fur led to extensive hunting and in some place, extirpation of the beaver. For more extensive general information see this Wikipedia article.

Beavers in Arizona:

According to the Arizona Game & Fish, beavers were at one time found nearly everywhere in Arizona that had permanent water. With settlement, and the desiccation of the state’s streams, beaver populations declined. This habitat loss, and in some cases, heavy trapping pressure, caused beavers to disappear from such former strongholds as the San Pedro and Santa Cruz rivers. Reintroduction programs and natural colonizations have since enabled the beaver to recover much of its former distribution, if not numbers, and these animals can now be found along several permanent streams, some of the larger river stretches, certain shallow lakes, and even a few dirt-lined canals.

The Winter, 2014, issue of Sonorensis pubished by the Arizona-Sonora Desert Museum has a good article on Arizona beavers (pages 18-23).

The article entitled “Aquatic Architects at Work: the Return of Beaver to the San Pedro River National Conservation Area” begins: “In 1826, trapper James Ohio Pattie dubbed the lower San Pedro River “Beaver River.” He and his party had been trapping beaver along the Gila River and its tributaries, but found that northern stretch of the San Pedro “very remarkable for the number of its beaver…At this place we collected 200 skins.”

The article claims: Beavers influence community diversity and ecosystem structure through tree felling and dam building. Beaver herbivory tends to result in large woody material in the floodplain, which enhances the amount of water that may be captured and stored. Water impounded behind beaver dams increases the area of riparian habitat, and, through groundwater recharge, leads to elevated water tables.

The United States Geological Survey, in cooperation with the University of Arizona recently published a paper which evaluated ecological benefits of restoring beavers to the San Pedro (read full study).

The paper’s abstract says:

We measured bird abundance and richness along the upper San Pedro River in 2005 and 2006 to investigate how beavers (Castor canadensis) may act as ecosystem engineers after reintroduction to a desert riparian area in the Southwestern United States. In areas where beavers colonized, we found higher bird abundance and richness of bird groups, such as all breeding birds, insectivorous birds, and riparian specialists, and higher relative abundance of many individual species—including several avian species of conservation concern.

After accounting for environmental factors, such as presence or persistence of surface water, and extent of Frémont cottonwood (Populus fremontii) and Goodding’s willow (Salix gooddingii), the relative influence of beaver activity was not as strong as these other environmental factors. However, there was still evidence of an association between beaver activity and bird abundance and richness, as models that included beaver-related variables better explained variation in bird abundance and richness for 71 percent of species groups and 46 percent of individual species for which we built models. Although the effect sizes associated with the beaver influence on the bird community were smaller than similar studies conducted in other regions of North America, the biological significance of beaver activity in the upper San Pedro River riparian area will likely become even stronger with increasing time.

AZ Game & Fish studied the suitability of re-establishing beavers in Cienega Creek. The 2008 study concluded that certain reaches were suitable.

You can see beavers at the Arizona-Sonora Desert Museum. ASDM has a story about a “beaver breakout” from the Museum. “One night, the beavers left their pond, waddled through the bighorn enclosure and escaped into the desert. The next morning Museum people followed their tracks, which headed west and before long stopped near a set of coyote tracks. Swirling beavertail prints in the sand showed how the beavers had made an about-face and headed back to the safety of their pond. They never attempted another escape.” source

See Article Index for more stories.

The American Badger – a very tenacious animal

badger USFWSBadger2

The American badger (Taxidea taxus) is known for its tenacity, power, and occasional ill-temper. The badger is a member of the Mustelidae family which includes skunks, otters, ferrets and weasels. There are four sub-species of badgers in North America which differ slightly in the size of the skull and color patterns of the fur.

The American badger is a carnivore and makes its living by digging for burrowing animals such as rodents, ground squirrels, prairie dogs, rabbits, and gophers. Given the opportunity, it will also prey upon, reptiles, birds and insects. It is preyed upon by eagles, cougars, and bobcats, but sometimes the badger can intimidate the predator with its hisses, growls, squeals and snarls and formidable teeth so that those predators leave it alone.

The American badger adult is about two feet long and weighs about 20 pounds. It has a wide body and short legs. It has a distinctive white stripe from forehead to nose. Its front feet carry curved claws up to two inches long, while the rear claws are shovel-shaped. Its fur is thick and shaggy.

According to the Arizona-Sonora Desert Museum (ASDM):

“Its eyes are equipped with nictitating membranes (transparent third eyelids) to protect them from flying dirt while the badger is digging. Small, well-furred ears also keep dirt out while the badger tunnels. A badger is able to secrete a musky scent from its anal glands, but it can’t spray this fluid like skunks can.”

According to DesertUSA:

“The American badger ranges across the western two thirds of the United States, the southern third of Canada’s western provinces, and northern mountain ranges in Mexico.”

“Within its habitat, the male badger often stakes out a territory of a square mile or more; the female, somewhat less. The male badger’s territory may overlap that of several females. It does not appear to mount especially aggressive defenses of its territory.”

“The badger, following a solitary lifestyle, ranges and hunts primarily at night. If it has no family, it may dig itself a new den, each with one entrance, virtually every day during the summer, when it is most active. It digs fewer dens in the fall as days begin to cool and its activity level declines. It may dig only a single den for most of the winter when temperatures become chilly to frigid, and its activity level falls to minimal. Although the badger does not hibernate, it may remain in its winter den for days or weeks without emerging. Fastidious, the animal, like a house cat, buries its droppings, and it often grooms itself.”

“Bearing total responsibility for rearing the young, the female prepares an elaborate burrow for her family. She may, in fact, dig 10 feet below the surface and excavate 30 or more feet of passageways. She fashions a grass-lined chamber for her offspring, which are born blind and helpless, bearing only a thin coat of fur and weighing only a few ounces. She nurses the youngsters for two or three months.”

See photos from NatureWorks.

The High Desert Museum in Oregon has a short video (badger on a leash):


About their temper: ASDM notes “Few animals care to tangle with an enraged badger. One badger even attacked a tractor that inadvertently ran over its den entrance.”

Dragonflies and Damselflies

Dragonfly 2

Dragonflies and damselflies (Order Odonata) are ancient creatures that have been around for about 250 million years. Both have very large eyes relative to body size compared to other insects. Dragonflies have a relatively wide thorax and hold their wings horizontally when perched. Damselflies have a slender thorax and hold their wings folded when perched. There are more than 5,000 species worldwide and about 400 species in North America.

The Order name, Odonata, means “toothed ones.” This refers to a prehensile lip-like structure in both nymphs and adults that can be extended forward very quickly to catch prey.

“Both dragonflies and damselflies begin their lives in the water. Dragonfly eggs are round and about 0.5 mm long, whereas damselfly eggs are cylindrical and longer, about 1 mm long. Similarly, the nymphs (larvae) of the two groups differ. A larval damselfly abdomen is longer and narrower with three fin-like gills projecting from the end. Dragonfly nymphs are shorter and bulkier, and the gills are located inside the abdomen. The dragonfly nymph expands and contracts its abdomen to move water over its gills, and can squeeze the water out rapidly for a short burst of underwater jet propulsion.” (Berkeley)

See photos of nymphs from the Dragonfly Woman blog here.

During the nymph stage, which can last two to three years and involve up to 15 molts, dragonflies and damselflies prey upon other insects, small fish, small tadpoles, and anything else they can catch.

The adults:

According to Berkeley:

Both dragonflies and damselflies have two pairs of elongated membranous wings with a strong cross vein and many small veins that criss-cross in the wings, adding strength and flexibility to the wings. Both groups also have a characteristic nodus, or notch, in the front edge of each wing. In dragonflies, the rear wings have a broader base and are larger than the front pair. Damselflies, by contrast, have front and hind wings similar in shape, and as a result they fly slower than dragonflies do. Also, dragonflies do not have hinges enabling them to fold their wings together when resting, though damselflies do. This feature of the wings is the key morphological feature distinguishing adult dragonflies from damselflies.

“Dragonflies can fly forward at about 100 body-lengths per second, and backwards at about 3 body-lengths per second. They are also capable of hovering in the air for about a minute. Longer periods of stagnant flight would interfere with thermoregulation. The wings of male dragoinflies are relatively longer and narrower than females in large species. Adult wingspans measure from 17 millimeters (Agriocnemis) to 20 centimeters (Coerulatus). Most temperate zone species have wingspans of 5 to 8 centimeters and wings that are from two to twelve centimeters from front to back.

“Dragonflies are generalists, that is, they eat whatever suitable prey is abundant. Oftentimes, they hunt in groups where large numbers of termites or ants are flying, or near swarms of mayflies, caddisflies, or gnats. According to most studies, the main diet of adult odonates consists of small insects, especially Diptera (flies). Maturing dragonfly larvae feed very intensively, as do females when developing their eggs. Studies show that food shortage may limit reproductive behavior. Dragonflies do not hunt in cold weather. Damselflies, however, are not as limited by temperature and have been observed hunting during cold spells. Males are territorial, sometimes patrolling for prey for hours at a time.”

The life span of adult dragonflies and damselflies is measured in hours to months.

The Arizona-Sonora Desert Museum describes them as follows:

“No predator soup would be complete without dragonflies and damselflies, the entire Order Odonata being predaceous, both as adults and nymphs. Damselfly nymphs have 3 leaf-like gills protruding from the ends of their abdomens, while dragonfly nymphs have spiny posteriors that suck oxygenated water into their rectums where the oxygen is absorbed. Many nymphs dart through the water by rapidly forcing the water out of their rectums—jet propulsion! The Libellulidae are usually brightly-patterned nymphs that crawl across the bottom searching for prey, while the Gomphidae sit and wait for their victims to stumble by. One gomphid is a flattened insect (with wide, flat antennae as well) that sits on the bottom, while another gomphid hides just under the sand, waiting for vibrations to indicate prey coming by. Quiver your hand over clean, shallow sand and watch for movement of this hidden insect. Another dragonfly (Cordulegasteridae), more common in pools in small, rocky streams, is hairy and usually covered with foreign material, camouflaged and motionless, waiting for prey.

“Most damselfly nymphs are slender. The Calopterygidae perch on plants or tops of rocks on long legs; they snatch insects and small crustaceans in quiet pools. Another damselfly in the family Coenagrionidae, the only odonate common in flowing water, crawls through leaves and roots of slow runs. Its more compact shape protects it from vagaries of the current.

“The face of a damselfly or dragonfly nymph appears to be covered by a toothed mask. This is actually a retractable set of mouthparts that can extend instantly up to 2 to 3 head-lengths in front of the insect, then open sideways to grab a victim. You can readily pull this contraption outward to see how it functions; dragonfly nymphs are particularly sturdy.

“Odonata adults cruise the streamside in search of flying insects, which they capture “on the wing” with legs that are covered with long hairs forming basket traps. Dragonflies extend broad wings outward, while damselflies’ slender wings are held back over the body. Skimmers (family Libellulidae) sit on the tips of plants, darting out to catch flying insects. They also patrol stream margins to defend their feeding and reproductive territories against other dragonflies.

“Odonate mating and oviposition behaviors are also complex. A male may appear to be looped awkwardly behind a female, using the claspers at his tail end to hold her “neck,” while contacting the genital openings to pass sperm. Damselflies like Argia often fly in tandem, the blue male attached to the tan female with his claspers. To defend his genetic contribution from competing males, he stays attached while she oviposits eggs into algal mats and other soft streamside materials. There are even reports that males of some species have hooks for pulling out sperm deposited earlier in the female by another male! Many female dragonflies and some damselflies release their eggs on the wing, touching their abdomens to the water during the release, or dropping the eggs from the air like dive-bombers. The eggs drift downward, becoming sticky enough when wetted to adhere to the bottom.”

For many photos see:



The BBC has several videos here:


Related articles:

Tarantula Hawks Deliver The Big Sting

Giant Mesquite Bugs

Scorpions, Vinegaroons, and Sun Spiders

See the ARTICLE INDEX for many more stories.

Creatures of the night – Ringtails

Ringtails ( Bassariscus astutus), also known as ring-tailed cats, are related to racoons and coatis. Ringtails are common in the Sonoran Desert, but are rarely seen because they are almost exclusively night prowlers.

A Ringtail adult is about 16- to 24 inches long and sports a bushy tail with white and black bands. The tail is usually longer than the body. Each dark eye is surrounded by a white ring.

Ringtail 2

This animal is found throughout the Southwest and into central Mexico. It is usually a canyon dweller. The Arizona-Sonora Desert Museum (ASDM) reports a “large” population near Tucson. During the day, the Ringtail occupies rock crevices, hollow trees, or caves. They are good climbers.

At ASDM, many of the exhibits in the cave may have footprints on the inside of the glass – Ringtails have managed to “get behind the scenes.”

Each Ringtail marks its territory with urine and droppings and it can emit a strong-smelling liquid from its anal glands (but can’t spray like a skunk).

Ringtails are omnivores that feed on rodents, fruit, birds, snakes, lizards, and insects. They have large eyes and a keen sense of smell.

According to ASDM:

“Ringtails inspect likely niches and hiding spots in their rocky habitats, hunting for rodents, birds, centipedes, and anything else edible. They are excellent mousers, pouncing and killing with a bite to the back of the rodent’s neck.”

“Ringtails are strictly nocturnal animals, using their large eyes and keen sense of smell to locate prey. They are excellent climbers and leapers, using their long tails for balance as they negotiate steep canyon walls or trees with equal ease. The ringtails have semi-retractable claws and can rotate their hind feet 180 degrees, allowing them to descend cliffs face first. They den in niches in rock walls, boulder piles, or hollow trees. Ringtails are solitary, only pairing up for a few days of mating in April. The two to four kits are born in June. By fall the young can hunt for themselves and soon disperse. Though fierce little fighters, ringtails fall prey to great horned owls, bobcats, and coyotes.”

Ringtail juvenile


The Ringtail is the official Arizona State Mammal. (Click the link to see more photos and a video.)

See the ARTICLE INDEX for more stories about the Sonoran Desert.


New Release – AZGS field guides to Arizona Geology

The Arizona Geological Survey has just e-published field guides to Arizona geology. The 422-page series of illustrated guides is available for free download at

These guides were originally published as the proceedings of the 100th annual meeting of The Geological Society of America (GSA) was held in Phoenix, Arizona in October 1987. The newly available online guides are organized into separately downloadable sections.

One guide that may be of interest to laymen is “The Archaeological Geology of Paleo.-Indian Sites in Southeastern Arizona” which begins on page 212 of the Southern Arizona section. This paper discusses the late Quaternary geologic history preserved in the sediments in the San Pedro Valley and the Sulphur Springs Valley in southeastern Arizona . “These sediments are host to some of the oldest archaeological remains in North America.” Along the San Pedro River near Tombstone, “The Murray Springs Clovis site is unique in that it contains three distinct activity areas where a band of Clovis hunters killed a mammoth and several bison and occupied a small campsite during two or three brief visits 11,000 years ago. The buried occupation surface is clearly displayed in the arroyo walls as an erosional contact at the base of a distinctive black organic mat that preserved artifacts and extinct animal bones in their original position, and mammoth tracks, just as they were left 11,000 years ago.”

Here are the papers and guides:


Field-Trip Guide for Marble Canyon and Eastern Grand Canyon

Field Guide to the Lower Grand Canyon, from Peach Springs to Pierce Ferry

Geology of the Lower Grand Canyon and Upper Lake Mead by Boat–An Overview

Geology of the Grand Canyon – A Hike Through Time

Upper Holocene Alluvium of the Southern Colorado Plateau

Late Pleistocene Alluvium and Megafauna Dung Deposits of the Central Colorado Plateau

Late Cenozoic Volcanism in the San Francisco and Mormon Volcanic Fields

A Field Guide to the Jemez Mountains Volcanic Field, New Mexico

Stratigraphy, Correlation, and Tectonic Setting of Late Cretaceous Rocks in the Kaiparowits and Black Mesa Basins

Field Guide to Sedimentary Structures in the Navajo and Entrada Sandstones in Southern Utah and Northern Arizona


Late Paleozoic Depositional Systems, Sedona-Jerome Area, Central Arizona

Tectonic and Magmatic Contrasts Across a Two-Province Proterozoic Boundary in Central Arizona

Geomorphology and structure of the Colorado Plateau/Basin and Range Transition Zone


Land Subsidence and Earth-Fissure Formation in Eastern Phoenix Metropolitan Area, Arizona

Selected Hydrogeologic Problems in Central Arizona

The Archaeological Geology of Paleo-Indian Sites in Southeastern Arizona

Terraces of the Lower Salt River Valley in Relation to the Late Cenozoic History of the Phoenix Basin, Arizona

Late Cenozoic Deposits, Vertebrate Faunas, and Magnetostratigraphy of Southeastern Arizona

Caldera Structures Along the Apache Trail in the Superstition Mountains, Arizona

Field Guide to Lower- and Upper-Plate Rocks of the South Mountains Detachment Zone, Arizona

Structural Geology of the Rincon and Pinaleno Metamorphic Core Complexes, Southeast Arizona

Pinto Valley Copper Deposit

Tectonic Setting and Sedimentological Features of Upper Mesozoic Strata in Southeastern Arizona

Lower Cretaceous Coral-Algal-Rudist Patch Reefs in Southeastern Arizona


Paleoecology and Taphonomy of Recent to Pleistocene Intertidal Deposits, Gulf of California

Volcanic Structures and Alkaline Rocks in the Pinacate volcanic field of Sonora, Mexico

The Mesquite and Picacho Gold Mines: Epithermal Mineralization localized within Tertiary Extensional Deformation

Mesozoic Tectonics of Southeastern California

Field-Trip Guide to Parts of the Harquahala, Granite Wash, Whipple, and Buckskin Mountains,
West-Central Arizona and Southeastern California

Metamorphic Core Complexes, Mesozoic ductile Thrusts, and Cenozoic Detachments: Old Woman Mountains-Chemehuevi Mountains Transect, California and Arizona

Miocene Extension, Volcanism, and Sedimentation in the Eastern Basin and Range Province, Southern Nevada

Crustal Transect: Colorado Plateau-Detachment Terrane-Salton Trough

Western Honey Bees and colony collapse disorder

Bee-in-saguaroMost bees in the Tucson region are solitary and live in burrows. Socialized bees in our region include the introduced honey bee, Africanized bees, and the native black and yellow bumblebees. For all bees, only the females sting. The stinger is an adaptation of the ovipositor, or egg laying structure. If the barbed stinger is left in the victim, the act usually rips the abdomen of the bee and causes it to die.

In this article, I will give general information about the honey bee, discuss its difference from the bumblebee, and comment on the over-hyped “colony collapse disorder.”

Western Honey bee:

The western honey bee (Apis mellifera) is native to Europe, Asia, and Africa and was introduced to North America during the 1600s.

Each colony has a Queen that is usually the only fertile female. Drone bees are the males whose primary job is to fertilize the Queen. Worker bees are females that are usually infertile.

According to Wikipedia:

“In the temperate zone honey bees survive winter as a colony, and the queen begins egg-laying in mid- to late winter in preparation for spring (probably triggered by day length). The only fertile female, she lays the eggs from which all the other bees are produced. Except for a brief period (when she may fly to mate with drones or leave in later life with a swarm to establish a new colony), the queen rarely leaves the hive after the larvae have become bees. She deposits each egg in a cell prepared by worker bees. The egg hatches into a small larva fed by “nurse” bees (worker bees who maintain the interior of the colony). After about a week, the larva is sealed in its cell by the nurse bees and begins its pupal stage. After another week, it emerges as an adult bee.

“For the first ten days of their lives, female worker bees clean the hive and feed the larvae. After this, they begin building comb cells. On days 16 through 20, workers receive nectar and pollen from older workers and store it. After the 20th day, a worker leaves the hive and spends the remainder of its life as a forager. The average population of a healthy hive in midsummer may be as high as 40,000 to 80,000 bees. The larvae and pupae in a frame of honeycomb are known as “frames of brood”, and are sold (with adhering bees) to start new beehives.

“Workers and queens are fed royal jelly during the first three days of their larval stage. Workers are then switched to a diet of pollen and nectar (or diluted honey), while queens will continue to receive royal jelly (which helps large, sexually developed larvae reach the pupal stage more quickly). Queen breeders consider good nutrition during the larval stage critically important for queen quality, with good genetics and sufficient mating contributing factors. During the larval and pupal stages, parasites may damage (or destroy) the pupa or larva.

“Drones are the colony’s male bees. Since they do not have ovipositors, they do not have stingers. Drone honey bees do not forage for nectar or pollen. The primary purpose of a drone is to fertilize a new queen. Many drones will mate with a given queen in flight; each will die immediately after mating, since the process of insemination requires a lethally convulsive effort.”

Is it a honey bee or a bumblebee?:

Here is how to distinguish honey bees from bumblebees. Honey bees are slender; bumblebees are bigger, more rounded and very hairy. Honey bees have many stripes while bumblebees usually have more blocky coloration. See photos and a chart from Alex Wild here.

Honey bees live in large colonies with as many as 50,000 workers. Bumblebee colonies generally contain 100 to 400 individuals. Bumblebees are in the genus Bombus and there are more than 250 known species. Both Honey bees and bumblebees feed on nectar and are important agricultural pollinators.

Colony Collapse Disorder (CCD)

From the Property and Environment Research Center (PERC), June 5, 2015:

“You’ve probably heard by now that bees are mysteriously dying. In 2006, commercial beekeepers began to witness unusually high rates of honeybee die-offs over the winter — increasing from an average of 15 percent to more than 30 percent. Everything from genetically modified crops to pesticides (even cell phones) has been blamed. The phenomenon was soon given a name: colony collapse disorder.

“Ever since, the media has warned us of a “beemaggedon” or “beepocalypse” posing a “threat to our food supply.” By 2013, NPR declared that bee declines may cause “a crisis point for crops,” and the cover of Time magazine foretold of a “world without bees.” This spring, there was more bad news. Beekeepers reported losing 42.1 percent of their colonies over the last year, prompting more worrisome headlines.

“Based on such reports, you might believe that honeybees are nearly gone by now. And because honeybees are such an important pollinator — they reportedly add $15 billion in value to crops and are responsible for pollinating a third of what we eat — the economic consequences must be significant.

But here’s something you probably haven’t heard: There are more honeybee colonies in the United States today than there were when colony collapse disorder began in 2006. In fact, according to data released in March by the Department of Agriculture, U.S. honeybee-colony numbers are now at a 20-year high. And those colonies are producing plenty of honey. U.S. honey production is also at a 10-year high.”

Read entire article (with links to other articles).

A local Tucson beekeeper adds: “It occurs mainly in ‘managed colonies’ and the cause is not known. Historically, it has happened before the advent of modern pesticides and the use of microwave towers. My guess it that is a navigational disorder caused by some pathogen(s) which disrupts the worker bees ability to find the way back to her colony. This is aberrant behavior since healthy workers would never abandon their colony leaving behind brood and a queen.”

A review of CCD published in PubMed from the National Center for Biotechnology Information concurs: “There is a growing consensus that colony mortality is the product of multiple factors, both known and unknown, acting singly or in combination.” And that, folks, is the definitive answer from government sources.

Related articles:

Carpenter Bees – black and gold and smelling like roses

Desert Bees and Africanized Bees

See also:

Cochineal the Little Red Bug

Giant Mesquite Bugs

Tarantula Hawks Deliver The Big Sting

Who’s Afraid of Tarantulas?

Venomous Centipedes and Cyanide-Oozing Millipedes


River Otters in Arizona

River otterThe northern river otter (Lontra canadensis) is widespread in North America, mainly in Canada, the Pacific Northwest, and along the U.S. east coast. There are seven subspecies and one Lontra canadensis sonora lives (or lived) in Arizona. It is called the Southwestern or Arizona river otter. You can see one at the Arizona-Sonora Desert Museum (ASDM).

Historically, the Arizona river otter occurred along the Colorado and Gila Rivers and their tributaries. In 1981-1983, a Louisiana subspecies was introduced into the Verde River in central Arizona.

River otters live in streams, coastal marine habitats, marshes, and swamps. They can tolerate both warm and cold climates.

According to ASDM, they build dens in the burrows of other animals, in hollows under logs, trees or rocks and along river banks. The dens generally have underwater entrances.

River otters eat a large variety of aquatic animals including amphibians, fish, turtles, crayfish, and crabs. They also eat birds and bird eggs. The otter’s long whiskers help them find prey when vision is obscured by dark water or other hiding places. Otters can remain under water for as long as eight minutes. In most places they hunt in water at night, but may also hunt during the day.

Breeding generally takes place in water, once a year, in late winter or early spring. A male may copulate with several females. According to ASDM, “Gestation is estimated to be around two months, but because otters employ delayed implantation, gestation can last up to a year.” “The young are fully-furred, but helpless at birth. Young open their eyes after one month and are weaned at about three months.” “Young reach sexual maturity after two or three years and can live eight to nine years in the wild.”

Except in the mating season, river otters are generally solitary. They are playful and exhibit such behavior as mud or snow sliding. ASDM notes that “play activities actually serve…to strengthen social bonds, to practice hunting techniques and to sent mark.” River otters can swim fast and run on land as fast as 18 mph.

River otters mark their territory with a power musk produced from glands at the base of their tail. They also use urination and defecation to mark their territory.

River otters may be preyed upon by bobcats, coyotes, and birds of prey.

See the Article Index for more stories of the Sonoran Desert.

Jumping Cactus -Chain-fruit and teddy bear cholla cactus

I write about the chain-fruit and teddy bear cacti together because both are called “jumping chollas” or “jumping cactus.” Of course, they don’t actually jump at you, but if you happen to brush against them, even slightly, they become very attached to you. Both cacti propagate mainly by clonal rooting of joints or fruit.

The chain-fruit cholla (Opuntia fulgida or Cylindropuntia fulgida) is so called because new fruits grow from aureoles on older fruit. The aureoles contain stem cells which can give rise to branches or buds.

Cholla chain fruit

Cholla chain fruit flower

Chain-fruit cholla range throughout south-central Arizona and northern Sonora. They may have several trunks and grow to about eight feet high on average, but can get over 12 feet high. The stem and fruits are green. Purplish-pink flowers usually open in the afternoon during the summer. The fruit and flowers generally hang down from branches.

The fruits may contain viable seeds, but more often fallen fruit takes root in clonal asexual reproduction. This cactus tends to form dense clonal colonies on the finer soils of bajadas and valleys.

The not so cuddly teddy bear cholla (Opuntia biglovii or Cylindropuntia biglovii) is so called because in certain light, its dense yellow spines (which are barbed) appear fuzzy. The teddy bear cholla has a single trunk, three to five feet high, with densely-packed side branches on the upper part of the plant. Yellow-green flowers give rise to spineless fruit that usually contain no fertile seeds. The teddy bear cholla survives in the warmest parts of the Mohave Desert and the hotter, drier parts of the Sonoran Desert. This cactus seems to prefer rocky habitat.


Cholla teddy bear flower

According to the Arizona-Sonora Desert Museum:

“The detached joints will readily generate new plants by rooting and branching. During cooler months, the terminal joints are detached by a slight touch by a passing animal or even a strong wind. “

There are many myths associated with “jumping” cactus. According to ASDM:

“One myth is that the joints are attracted to the moisture in animal flesh. Many people believe that they really do jump, and some even claim to have caught them in the act. The truth is that the very sharp spines are so well-barbed that even if one barely penetrates the skin or clothing, its grip is stronger than the connection between joints. If you pass a jumping cholla and turn to look when you feel a tug on your clothing, you may see the joint detaching and flying through the air as the elastic recoil of the cloth snaps it into your flesh. The double surprise of seeing a plant moving faster than you and the sharp pain of impalement leaves a lasting impression.”

“The easiest way to remove a cholla joint is to place a comb between it and your skin and quickly jerk it away. Because of the barbs, it will take considerable force to dislodge it, and the joint may fly several feet. Make sure a hapless companion is not in the line of fire.”

The fruit of both chollas generally does not ripen. Cactus wrens make use of these cacti for nesting sites, and pack rats use the joints to fortify their dens.

Reference: A Natural History of the Sonoran Desert, 2000, Arizona-Sonora Desert Museum Press

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New map identifies aggregate resources of Phoenix Metro area

The Arizona Geological Survey has just published its first ever derivative aggregate map product. It is designed to help local communities and zoning groups manage and conserve their aggregate resources. In 2011, AZ legislators passed a law requiring communities to take in to account local aggregate resources as they zoned their communities.

Rivers of the Phoenix area drain large watersheds with diverse types of bedrock, and bed load that has been deposited in the Valley of the Sun. Commonly, this rock has been transported for tens of miles or more providing a natural filtering that removes less resistant rock and results in a high-quality rock product for use in various types of aggregate. This map product depicts the deposits associated with each of these rivers and reflects variations in rock type and gravel size.

Citation: Pearthree, P.A., Gootee, B.F., Richard, S.M. and Spencer, J.E., 2015, Geologic Map Database for Aggregate Resource Assessment in the Phoenix Metropolitan Area and Surrounding Regions, Arizona. Arizona Geological Survey Digital Information DI-43, 11 p., map sheet, Shapefiles, ArcGIS Map Packages, polygons and geologic features.

Here is the press release from the Arizona Geological Survey:

The Arizona Geological Survey has released its firstgeologic map database for aggregate resource assessment in the Phoenix metropolitan area. This map product will provide the basis for local and county planning and zoning authorities to make informed decisions regarding conservation and management of aggregate resources.

Sand, gravel and crushed stone, collectively referred to as aggregate, are the basic ingredients for constructing buildings, homes and infrastructure. In rapidly urbanizing areas, aggregate resources, which frequent river channels and floodplains, are threatened by urbanization and zoning that prevents their development.

The Aggregate Protection section of the Regulatory Bill of Rights, SB 1598, of 2011 requires that counties and municipalities revise their general plans to identify aggregate in their jurisdiction, and implement policies to preserve aggregate resources for future use by avoiding incompatible land use.

This new report, map graphic, and GIS (geographic information system) data shows the distribution of unconsolidated sediments (sands and gravels) from Phoenix’s five major rivers systems – Salt, Gila, Verde, Agua Fria and Hassayampa – and their tributaries. These channel deposits make the highest quality and most desirable aggregate resources.

Rapid population expansion in the Phoenix area and elsewhere in Arizona threatens to bury aggregate resources beneath urban growth, housing additions and infrastructure. As aggregate sites near communities are reduced or become off limits to quarrying, aggregate resources must be trucked in from ever more distant quarries.

Harvesting aggregate resources locally greatly reduces transportation costs -a major component of the aggregate cost. Using local sources also reduces road wear and diesel fuel consumption, thereby greatly reducing the emission of CO, NOx, particulate matter 10 micrometers, SOx, and volatile organic compounds.

Aggregate PHX