Natural History

Inca Doves – small and surprising

The Inca Dove (Columbina inca) is a small dove with a body length of about 8 inches. It is smaller than a Mourning dove and the White-winged dove. The Inca Dove’s color is light brownish gray and has a scaled appearance on its back. The tail is slender and has white sides. At rest, this dove is very dull looking. That changes in flight or when the dove is displaying. Then the bright rufus-colored primaries on the underside of the wings are visible. Male doves use the display of raising one wing over their backs to defend their territory against other males.

During courtship, the male bobs its head, raises its tail high over back and spreads it widely to show off black and white markings.

Inca doves occur in the southwestern U.S. and most of Mexico. They are found around human settlements throughout much of the Sonoran Desert region. They seem to prefer open areas with sparse shrub cover and scattered trees such as palo verde and oak.

They are seed and fruit eaters. Doves grind seeds in their muscular stomachs (or gizzards) using sand or gravel much like internal teeth.

According to the Arizona-Sonora Desert Museum, “The Inca Dove has the longest breeding season of any Arizona bird: January to November. That fact, plus its preference for grass and weed seeds, have made the Inca Dove the most abundant bird in southwestern urban areas, after the house sparrow.”

According to Audubon, Nest sites vary, usually in trees or shrubs 5-20 feet above ground, sometimes as high as 50 feet. Nests (built by female, with material gathered by male) are a small platform of twigs, stems, leaves, sometimes lined with grass.

Both parents incubate the eggs for about two weeks. Upon hatching, the chicks are fed “pigeon milk” produced by both parents. “Both males and females produce this substance in their crops (the pouch just above the stomach that birds use to store food). The walls of the crop swell with fat and proteins until the cells in the crop wall begin shedding, producing a nutritious, milky-colored secretion. Despite its appearance, it’s not related to the milk produced by mammals.” – (Cornell)

The chicks fledge within two weeks of hatching and may be tended by the parents for another week or two.

Inca doves have a distinct sound. Listen here. Do you recognize it?

See also:

White-winged Doves

Mourning Doves

Eurasian Collared-Doves

Golden Paper Wasps

Paper wasps (genus Polistes) are the most common wasps of the Sonoran desert. They are about one inch long and often brightly colored (see photo gallery). According to the Arizona-Sonora Desert Museum, common paper wasps include the yellow (aka golden) paper wasp, the Navajo paper wasp, which is deep chocolate brown with the end of the abdomen yellowish; and the Arizona paper wasp, which is slightly smaller and more spindle-shaped than the other two and is brownish-red with thin yellow cross bands on the abdomen.

A golden paper wasp (Polistes aurifer) has been inspecting my house recently, but so far, I have not seen any nests. This wasp drinks from my pool. It can land on and walk on the water because it does not break surface tension. These wasps are not usually aggressive except when defending a nest. The nest is built using tree bark and wood fibers mixed with saliva.

ASDM: The paper wasp is a social insect whose life cycle begins as a solitary mated queen. The queen overwinters deep in rock cracks, behind peeling tar paper, or inside enclosures. In spring the queen builds a paper nest suspended from a thin stalk in a protected rock crevice, among thick vegetation such as dead fan palm leaves, or under the overhang of a man-made structure. She constructs a small cluster of paper hexagonal cells and lays an egg in each. The queen then feeds the larvae that hatch from these eggs a diet of caterpillar ‘meat balls.’ When the first young worker wasps emerge from their pupal cells, they assume the tasks of hunting caterpillars, collecting material for making papier-mâché for nest expansion, and collecting water for cooling. The queen then ceases all work except egg laying. By late spring, the colonies have grown to contain 20 to 50 wasps; by late summer as many as 200 wasps may be present. At this time new queens and males are reared. After mating, the new queens imbibe nectar to fatten for the winter. By late fall, the queen mother and workers die, the nest is abandoned, and the next generation of queens goes into hibernation.

Most wasps are specialized hunters that track down their prey using smell and sight combined with knowledge of the habitat, activity periods, and behavior of the prey. A solitary wasp usually subdues its prey with a sting that either kills the prey or paralyzes it briefly or permanently. (Tarantulas stung by tarantula hawks can live completely paralyzed for months.) Social wasps, including paper wasps, never sting their prey. Instead, they use their powerful cutting mandibles to chew the prey into pieces to feed directly to their larvae. The venom of social wasps is used only for defense. (Read more from ASDM)

Most wasps are carnivores that feed on other insects and arthropods. A few species have become herbivores, like bees, and feed on nectar and pollen.

Although wasps are not pleasant to have around, they are beneficial because they are pollinators.

See also: Tarantula Hawks Deliver The Big Sting  

Ocelots – an occasional Arizona visitor

Ocelots (Leopardus pardalis) are medium-sized, spotted neotropical cats whose principal range is Central and South America. They also occur in Mexico, South Texas, and occasionally in southern Arizona.

Juvenile bobcats and mountain lions may be mistaken for ocelots because they, too, are spotted. Another spotted cat is the Margay, but it is much smaller, about the size of a house cat.

Full-grown ocelots have a head and body length of 22 to 38 inches, a tail length of 8 to 10 inches. They can weigh between 18 and 35 pounds. The smaller ocelots tend to occur in the northern part of their range. Ocelots are quite varied depending on location and there are 10 recognized subspecies.

Ocelots have a distinctive bright white spot within black on the back of their ears. Their short smooth body fur is creamy colored on the sides and back and whitish underneath. Both areas sport black spots.

According to the Arizona-Sonora Desert Museum, “Ocelots prefer dense thornscrub, live oak scrub, or riparian areas with an overstory cover.”

Ocelots hunt mainly at night, but may be seen during cloudy or rainy days. Ocelots are solitary animals that maintain territories which are scent-marked by urine spraying and forming dung piles. Males have territories up to 18 square miles. Females have territories of up to 6 square miles. Male territories can overlap several female territories. Social interaction is minimal.

Ocelots feed on a variety of small mammals and birds, as well as some reptiles, amphibians, and fish. They also take young pigs, kids, and lambs, and domestic poultry. Ocelot dens may be a cave in a rocky bluff, a hollow tree, or the densest part of a thorny thicket. Two young are born in late summer or fall. Like other young of the cat family, they are covered with a scanty growth of hair, and the eyes are closed at birth. Gestation has been estimated to last 70-80 days and captive kittens opened their eyes 15-18 days after birth. (Source)

Arizona Game & Fish Department biologists investigate and keep track of ocelot sightings in Arizona. See reports and photos: Feb 5, 2012 in Huachuca Mountains, and another report of the same incident here. Sighting in Cochise County, Dec 2, 2011.

An ocelot was photographed between April 8 and May 21, 2014 near the site of the proposed Rosemont mine in the Santa Rita Mountains according to the US Fish & Wildlife Service. That sighting came two days before the U.S. Forest Service delayed its final decision on the $1.2 billion mine project, in part because of the ocelot. – Arizona Daily Star

Ocelots have been extensively hunted for their fur, kept as pets, and worshiped by ancient Central and South American cultures.

Black-bellied Whistling Ducks

Black-bellied Whistling ducks (Dendrocygna autumnalis) range from southern Arizona, south Texas and Louisiana, through parts of Mexico and Central American to Brazil. Their range is expanding northward.

These large ducks (body length about 22 inches, wingspan 37 inches) are reddish brown, have a black belly, white wing patches, and a pink to orange bill. They are long-legged, long-necked, and are sociable and noisy. The Cornell Lab of Ornithology describes them as “boisterous.”

My own experience with these ducks is confined to the mixed-species aviary at the Arizona-Sonora Desert Museum. Often, a gang of these noisy ducks will follow me around, pecking at my legs and attempt to untie my shoelaces.

Whistling ducks can be found in marshes, ponds, and lakes where they feed on aquatic animals such as snails. Their main diet, however, consists of seeds and grains. Whistling ducks frequent grasslands and agricultural areas where they feed on many agricultural crops including sorghum, millet, corn, rice, and wheat. They also eat insects and spiders.

Whistling ducks are casual about nesting. According to the Cornell Lab of Ornithology: they usually nest in tree hollows where a limb has broken or the trunk has rotted away. They typically don’t build a nest; they lay their eggs directly on whatever debris has collected there. Cavity openings range from 5–12 inches across. When nesting on the ground, they make a scrape or a shallow bowl of grasses, with thick vegetation overhead, such as willow, mesquite, or cactus. They typically lay 9 to18 eggs which are incubated for 25 to 30 days. Hatchlings are nearly independent upon hatching.

About the noise. Whistling ducks do not make the “quacking” noise of other ducks. Rather they have a range of sounds. Listen here.

According to ASDM, United States populations are increasing, probably because of nest boxes. This species was rare in Arizona before 1949 but has since become a rather common nesting bird.

Stingrays in the desert

You probably don’t think of stingrays when visiting the desert. However, several species of stingrays inhabit the Gulf of California which is part of the Sonoran Desert. Last October, the Arizona Sonora Desert Museum opened a new exhibit featuring cownose stingrays. At the Museum, the stingers have been clipped. The exhibit allows the sting rays to touch you (rather than you touching the rays). They feel like wet velvet. The skin of a ray is covered by tooth-like structures (called dermal denticles) instead of scales like fish.

Rays are bottom feeders. “Besides gills, rays have an extra adaptation to help them breathe while resting on the bottom of the ocean. These special openings, which are near their eyes, are called spiracles. Instead of sucking sandy water in through their gills, they can pull clear water in through their spiracles. They then push the water out through their gill slits.” (ASDM)

Stingrays (skates and ratfishes) are close relatives of sharks and evolved from sharks about 200 million years ago during the Jurassic Period. Like sharks, rays have a cartilaginous skeleton rather than hard bones. In rays, the front fins have expanded around the head to form a pectoral disk that act like wings. Most rays are marine animals, but some have evolved to tolerate brackish and fresh water.

Differences between bony fish and rays (info from Arizona Sonora Desert Museum):

Bony fish have a bony skeleton, overlapping ganoid, cycloid or ctenoid scales, a gill opening covered by a bony plate called an operculum, flexible pectoral fins, a swim bladder and internal fertilization. The operculum allows fish to actively pump water over their gills. Having flexible pectoral fins made up of fin rays allow bony fish to be more maneuverable, navigate tight spaces, and the ability to turn around. A swim bladder is a gas filled organ that helps control the buoyancy of a bony fish.

Sharks and rays a cartilaginous skeleton, tooth-like scales called dermal denticles or placoid scales, five to seven pairs of gill slits, no swim bladder, very large liver, fixed pectoral fins, spiral valve intestine, specialized electroreceptors called the ampullae of Lorenzini, and internal fertilization. Since cartilaginous fish lack a swim bladder for buoyancy, they have a significantly enlarged liver filled with oil called squalene that helps them float.

The following photos and information, from the Arizona Desert Museum, shows the rays which inhabit the Gulf of California. Visit the museum and be touched by a ray.

 

Humans caused 84% of US wildfires from 1992 to 2012

Although climate change has been blamed for an increase of wildfires in the United States, a new paper, published in the Proceedings of the National Academy of Sciences, concluded that 84% of fires were ignited by humans and this extended the fire season by a factor of three.

Here is the paper abstract:

The economic and ecological costs of wildfire in the United States have risen substantially in recent decades. Although climate change has likely enabled a portion of the increase in wildfire activity, the direct role of people in increasing wildfire activity has been largely overlooked. We evaluate over 1.5 million government records of wildfires that had to be extinguished or managed by state or federal agencies from 1992 to 2012, and examined geographic and seasonal extents of human-ignited wildfires relative to lightning ignited wildfires. Humans have vastly expanded the spatial and seasonal “fire niche” in the coterminous United States, accounting for 84% of all wildfires and 44% of total area burned. During the 21-y time period, the human-caused fire season was three times longer than the lightning-caused fire season and added an average of 40,000 wildfires per year across the United States. Human-started wildfires disproportionally occurred where fuel moisture was higher than lightning-started fires, thereby helping expand the geographic and seasonal niche of wildfire. Human-started wildfires were dominant (>80% of ignitions) in over 5.1 million km2 , the vast majority of the United States, whereas lightning-started fires were dominant in only 0.7 million km2, primarily in sparsely populated areas of the mountainous western United States. Ignitions caused by human activities are a substantial driver of overall fire risk to ecosystems and economies. Actions to raise awareness and increase management in regions prone to human-started wildfires should be a focus of United States policy to reduce fire risk and associated hazards.

Read the full paper here:

http://www.pnas.org/content/early/2017/02/21/1617394114.full.pdf?sid=97323811-0b09-4bfb-a5d8-8b6480f6aa0f

Sowthistle – a new weed in my yard

sowthistle1A new weed has sprouted in my yard. With the help of a botanist at the Arizona-Sonora Desert Museum, this new plant is identified as the genus Sonchus, commonly called sowthistle. Sowthistle species occur in temperate zones worldwide. Arizona has two species, Common Sowthistle (Sonchus oleraceus), the one in my yard, and Spiny Sowthistle (Sonchus asper). These plants are related to dandelions and are members of the sunflower family. For an idea of the plant size, the large leaf in the center of the photo is 10 inches long.

The name “Sowthistle” refers to the fact that pigs are especially fond of the leaves and stems. So are rabbits. This plant is also called “hare thistle” or “hare lettuce” in some parts of the world.

The leaves are also used by humans, especially in Chinese cooking. The leaves can be eaten as a salad green or cooked and used like spinach. Blanching removes a slightly bitter taste. (Source) I have not tried it.

“This plant has powerful medicinal properties, with some toxicity, but at the same time it is also highly nutritious. It contains, per 100g, around 30mg of vitamin C, 1500 mg of calcium and 45 mg of iIron. The dried leaves contain up to 28g of protein per 100g – a great nutritional supplement. Use only young leaves as edibles, raw, in salads or cooked, as spinach.” (Source)

Medicinal uses are the same as for dandelions:

“In the past, dandelion roots and leaves were used to treat liver problems. Native Americans also boiled dandelion in water and took it to treat kidney disease, swelling, skin problems, heartburn, and upset stomach. In traditional Chinese medicine (TCM), dandelion has been used to treat stomach problems, appendicitis, and breast problems, such as inflammation or lack of milk flow. In Europe, dandelion was used in remedies for fever, boils, eye problems, diabetes, and diarrhea.” (See more from the University of Maryland Medical Center.)

Sow thistles exude a milky latex when any part of the plant is cut or damaged, and it is from this fact that the plants obtained the common name, “sow thistle”, as they were fed to lactating sows in the belief that milk production would increase. Sow thistles are known as “milk thistles” in some regions, although true milk thistles belong to the genus Silybum. (Source)

The yellow flowers are about 1.25 inches in diameter and attract bees, flies, and aphids. The flowers turn into dandelion-like tufts and the seeds go floating off in the wind.

Common Sowthistle is classified as an annual herb and can grow up to four feet high. Other species of Sonchus are perennials.

Opossums in Arizona?

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opossum2

Opossums are common in the eastern US but are rare in the west. Strangely enough, the so-called Virginia opossum (Didelphis virginiana) occurs in Tucson and other parts of Arizona. This is the only species of marsupials that occurs in the US. (Marsupials nurse their young in pouches. The kangaroo is probably the best known marsupial.)

An amusing decription written in early Spanish colonial times quoted in an article in Scientific American, describes an opossum as “a monstrous beast with a snout like a fox, a tail like a marmoset, ears like a bat, hands like a man, and feet like an ape, bearing her whelps about with her in an outward belly much like a large bag or purse.” (Source)

According to Wikipedia:

Virginia opossums can vary considerably in size, with larger specimens found to the north of the opossum’s range and smaller specimens in the tropics. They measure 13–37 in long from their snout to the base of the tail, with the tail adding another 8.5–19 in. Weight for males ranges from 1.7 to 14 lb and for females from 11 ounces to 8.2 lb. They are one of the world’s most variably sized mammals, since a large male from northern North America weighs about 20 times as much as a small female from the tropics. Their coats are a dull grayish brown, other than on their faces, which are white. Opossums have long, hairless, prehensile tails, which can be used to grab branches and carry small objects. They also have hairless ears and a long, flat nose. Opossums have 50 teeth, more than any other North American land mammal, and opposable, clawless thumbs on their rear limbs.

Opossums have 13 nipples, arranged in a circle of 12 with one in the middle. Perhaps surprisingly for such a widespread and successful species, the Virginia opossum has one of the lowest encephalization quotients of any marsupial. Its brain is one-fifth the size of a raccoon’s.

Opossums are mainly nocturnal and omnivorous. A large part of their diet is insects and other invertebrates, but they also eat the eggs of chickens and wild birds, fruits and berries, pet food left out in the yard, and garbage.

According to an article in the Journal of Mammology (November, 1952), an adult female opossum was captured (December, 1949) at the Rincon Stock Farm on Fort Lowell Road in Tucson. The following May, an adult male was found about four miles from the Farm. The author of this paper speculates that these animals were introduced from elsewhere, although he does mention that wild opossums lived in eastern New Mexico at the time.

A more recent article (2011) in the Western North American Naturalist journal reports opossums in Yavapai County, Arizona. The paper’s abstract reads:

The Virginia opossum (Didelphis virginiana) is the only marsupial native to the United States. In recent times, D. virginiana has expanded its range through natural movements and anthropogenic introductions. Didelphis virginiana has been present in southern Arizona owing to range expansion by the Mexican subspecies (D. v. californica) and anthropogenic introductions of the eastern subspecies (D. v. virginiana). Here, we document the recent collection of an opossum in central

Arizona. We also discuss how it possibly moved there and report on its stomach contents at the time of collection.

There are also reports of opossums in the Phoenix area.

Opossums react to a threat by feigning death, hence the saying “playing possum.” Opossums, like most marsupials, have unusually short lifespans for their size and metabolic rate. The Virginia opossum has a lifespan in the wild of only about two years.

There is some North American mythology about opossums. “In North America, Opossum sometimes appears in legends as a buffoon or braggart, whose habit of playing dead stems from embarrassment over having made a fool of himself. In Central America and parts of southern Mexico, Opossum occasionally plays the role of a trickster or an animal hero who escapes from danger by using his wits. Opossums are also symbols of fertility in some Mexican tribes, and a drink made with an opossum’s tail is still used by some Nahuatl women as folk medicine to help deliver babies. In some South American tribes, Opossum plays a more important mythological role as the Fire-Bringer.” Read more here.

opossum-facebook

The Cactus Mouse – another creature of the night

cactus-mouse-nps

The Cactus mouse (Peromyscus eremicus) is one of eight species in the genus Peromyscus that inhabit Arizona. All are similar-looking grayish-brown, with white bellies and feet, and large ears. They are about 3.5 inches long. The cactus mouse has a sparsely furred tail with a slight tuft at the tip. “Females weigh slightly more than males and are significantly larger in body length, ear length, length of mandible and bullar width of skull. Cactus mice can be identified by having naked soles on their hind feet, and almost naked tails which are usually the same length or longer than the animals body length.” (Source)

The Cactus mouse ranges from southern California and Nevada, through southern Arizona and New Mexico, west Texas into northern Mexico. They are common in washes and rocky hillsides, in sandy deserts and desert foothills. Depending on location, they may breed throughout the year. A female may produce 3 to 4 litters per year, each with 4 to 5 young.

cactus-mouse-range

Cactus mice are nocturnal feeders. They eat seeds, fruit, and succulent plant material. Their diet includes mesquite beans and leaves, and insects. During the day they remain in burrows in clumps of cacti, in the ground, or among rocks. Their nests are usually a ball of grasses or twigs.

According to the Arizona-Sonora Desert Museum:

“The cactus mouse often climbs around in vegetation and brush, searching for seeds and fruits to eat. It may nest in wood piles or rock piles, or use the abandoned burrows of other animals. Although this mouse needs less water than many others and is desert-adapted, it may estivate or go into a torpor in the summer when resources for food and moisture are not available.”

“These little rodents are at the bottom of the vertebrate food chain, preyed upon by everything from coyotes and snakes to hawks and bobcats. In response, they breed prolifically, with some species, like the cotton rats, able to produce eight to ten litters a year. Populations still fluctuate with drought and predation, but the mice and rats are able to respond to good conditions by rapidly rebuilding their numbers.”

“All rodents, including the mice and rats, are gnawers. Their teeth are ever-growing and must be kept trimmed down by constant gnawing. A layer of hard orange enamel covers the front surface of the teeth. The rest of the tooth is softer and wears down quicker than the enamel as the rodent gnaws, thus creating a chisel-like shape to the front teeth that is unique to the rodent family.”

Other desert rodents:

Creatures of the night – Pocket Mice

Ferocious Grasshopper mouse

Kangaroo rat

Pack Rats are Desert Archaeologists

 

 

 

 

 

 

 

Attack of the Phainopepla

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The Phainopepla (Phainopepla nitens) is a pretty bird, but around my house one has been pretty messy. For several weeks, a male Phainopepla has been feasting on the berries of a desert mistletoe plant. It has been peeping in the window. At times it attacks its reflection by pecking at the window and flying up and down the glass. It is apparently trying to drive off what it thinks is a competitor. Does he look angry?

The Phainopepla is a crested bird slightly smaller than a cardinal. It has a body length of 7- to 8 inches and a wingspan of 11 inches. The males are shiny black with red eyes, long tail and a white patch on the wings which is conspicuous in flight. Females and immature birds are all gray. The name “Phainopepla” comes from the Greek for “shining robe,” a fitting description of the shiny, jet-black plumage of the adult male. The Phainopepla is one of the four species of silky-flycatchers and the only one that occurs in the U.S. The others inhabit Mexico and Central America.

According to the Cornell Lab of Ornithology:

“… the Phainopepla is unique in taxonomy, distribution, and behavior. It is particularly notable for its enigmatic pattern of breeding twice each year, in two different habitats.” It breeds in both the desert and in arid woodlands.

Cornell says that “An individual Phainopepla eats at least 1,100 mistletoe berries per day, when they are available.” (My visitor deposits the remains of these sticky berries on my window ledge and ironwork.)

“The Phainopepla exhibits strikingly different behaviors in its two habitats. In the desert, it is territorial, actively defending nesting and foraging sites, while in the woodlands it is colonial, with as many as four nesting pairs sharing one large tree.

“The Phainopepla rarely drinks water, even though research indicates that it loses about 95 percent of its body mass in water per day. Instead, it gets the water it needs from its diet of mistletoe.” Phainopepla also eat other berries and flying insects.

According to the Arizona-Sonora Desert Museum:

“This bird nests in early spring in mesquite brushlands, usually well up in a stout fork or horizontal branch of a tree. The smooth, slightly glossy eggs usually number two to three per clutch, and are grayish-white or pinkish, finely and profusely spotted with black, pale lavender, or gray. The eggs are incubated by both sexes (possibly the major portion by the male) for 14 to 15 days. The young are tended by both parents and leave the nest at 18 to 19 days.”

The Phainopepla, when pursued by predators or handled by humans, mimics the calls of other birds; imitations of at least 13 species have been recorded. (Listen to sounds)

As the supply of mistletoe berries dwindle, my Phainopepla is now spending about half his time attacking a neighbor’s window which is a little closer to the berry source.

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 phainopepla-range-map