Pussy Willow

Pussy Willow

Pussy Willow

On Tuesday I found the first pussy willows (Salix sp.) of the season at Ash Creek Wildlife Area (Modoc County CA).  Of course I had to pick a few branches to take home.

Most everyone has admired the whitish grey, felt-like pussy willows, which are the first harbingers of spring. Most species of willows (there are over 300 worldwide) have furry flower buds. A Northeastern species (Salix discolor) is commonly considered “the” pussy willow, however, most of us do not distinguish between the different flowering willows when we see them early in the spring. All the willows with fuzzy catkins are “pussy willows”. Only later in the season do we worry about the proper identification.

The furry whiteish catkins are actually tightly bunched arrangements of stamens (male) or carpels (female). The stamens and carpels have attached silvery hairs. Catkins are either male or female. Willows are dioecious, meaning that the male and female catkins are on different plants. Most of the pussy willows that we see in early spring are male. The female catkins open later and often look slightly different.

The willow bud is covered by a single caplike scale. The silvery hairs are the first part of the bud to develop. By trapping the sun’s heat, the insulating hairs help keep the reproductive portions of the bud warm while they develop. Mature male catkins produce pollen on the anthers and the female catkins develop ovules in the carpels.

Willows rely on insects, particularly bees, for pollination. The catkins produce nectar very early in the spring and are important food sources for bees.

Pussy willows are used in Chinese (Lunar) New Year’s celebrations as symbols of prosperity. Eastern European Orthodox and some Catholics in both Europe and North America use pussy willows as an alternative to palm branches on Palm Sunday, since palms do not grow in more northern climates.

I am always excited to see the first pussy willows each year. Can spring be far behind?

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Sharp-shinned Hawk

Sharp-shinned Hawk

As the morning sun peeks over the mountains surrounding our house near Lookout CA (Modoc County), the songbirds outside my kitchen window are active and noisy.  Today I saw no small birds in the yard and it was eerily quiet – only the sounds of  cows and waterfowl in the distance broke the silence.

Then I saw the reason. Perched on the pasture fence was a juvenile sharp-shinned hawk (Accipiter striatus). All my usual morning companions had taken refuge or flown off. Small songbirds comprise about 90% of this accipiter’s diet. “Sharpies” catch their prey by ambush from a perch or while flying around. Their long toes and talons impale and hold moving prey until  they reach a perch where their victim can be killed and eaten.

The bird on the fence was a juvenile. Accipiters eyes start out yellow and turn red as the bird reaches maturity. Juvenile sharp-shinned hawks closely resemble young Cooper’s hawks (Accipiter cooperi). One of the easiest ways to tell the two species apart is by their tail: “coopers” have rounded tails while sharpies’ tails are squared off. Unfortunately the tail of this young bird was hidden. Size also separates sharpies from coopers with sharpies being smaller. The streaks on a sharpie’s breast are blurry and broad, extending down across the belly. Crisp streaks, mostly on the chest, define a coopers.

Once the sharp-shinned hawk gave up the hunt and moved on, the usual compliment of juncos, sparrows and other small songbirds returned.

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Sandhill Cranes Arrive

Sandhill Crane

Sandhill Crane

Each spring Leonard and I anxiously await the return of sandhill cranes (Grus canadensis) to Big Valley, our home. Snow may remain on the ground, yet the loud calls of sandhill cranes remind us that spring is at last on the way. Leonard and I have an informal competition with each other to see or hear the first sandhill cranes of the season.

Leonard won this year with a February 10th sighting. On the 11th we both verified that the cranes were indeed back. This year they returned at approximately the usual time. Since I have kept records, the sandhill cranes usually arrive between February 11th and February 17th. The earliest we noted a sandhill crane near our home was February 4th in 2015, the latest was February 25, 2009.

Sandhill cranes are either resident or long-distance migrants. Three subspecies of sandhill cranes live year round in Florida, Mississippi or Cuba. Three additional subspecies breed in northern North America and winter in the farmlands and open country, usually near lakes or marshes, of southern United States and northern Mexico. Migrating and wintering sandhill cranes often gather in flocks numbering in the thousands. The largest group of sandhill cranes I ever saw numbered several hundred and was observed in the summer at Ash Creek Wildlife Refuge (Modoc County CA).

Sandhill cranes mate for life (with luck, 20 years or more) and remain together throughout the year. Females choose their mates on the basis of the males’ dance displays. Sandhill cranes can begin to breed at two years of age and some do not mate until they are seven years old.

This sandhill crane was photographed along County Road 87 near our home in Lookout CA.

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ZW Gender Determination

White-crowned Sparrow

White-crowned Sparrow

Sex determination in mammals and most other animals is via the XY chromosome system. Simply put, the X and Y chromosomes determine the sex of the offspring. A female has two X chromosomes, one from the father and one from the mother, while a male has one X chromosome and one Y chromosome, the X from the mother and the Y from the father. In humans and most other animals, the default reproductive organs are female. Male organs develop only in the presence of a male determining gene/protein. This male gene is carried on the Y chromosome. The sperm determines sex in the XY system.

Recently while reading “The Gene” by Siddhartha Mukherjee, I was surprised to learn that in birds and some reptiles, insects, fish and crustaceans there is a different system for determining gender. I had no idea and had to do some research.

In these other animals sex is determined by two completely different chromosomes, the Z and W chromosomes. The ZW chromosomes were derived from a different pair of ancestral chromosomes than the XY chromosomes. Both the XY and ZW ancestral chromosomes were ordinary chromosome in reptilian times. However, once the male-determining gene “landed” on the Y chromosome, the Y started shedding genes held in common with the X chromosome and the Y chromosome shriveled to a fraction of its former size.

The sex-determining gene in birds is on the Z chromosome and the entire system is reversed. A male bird has two Z chromosomes while the female has one Z and one W chromosome. A bird’s sex is determined, not by the simple presence of the sex-determining gene, instead, it is regulated by the amount or “dose” of the sex-determining gene. A female with ZW chromosomes has one dose of the sex gene while the male with ZZ chromosomes has two doses of the sex gene. Two doses are required to develop male reproductive organs. The ovum (egg) in this case determines sex.

Why this reversal of systems in birds and some select other animals? From my reading I discovered several convoluted suggestions, none of which seems totally satisfactory to me. Research on the ZW gender-determining system is ongoing and more information and answers should continue to appear in the literature.

The bird picture is just a generic picture – a pretty white-crowned sparrow (Zonotrichia leucophrys)  photographed in our yard (Modoc County CA) last summer.

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This gallery contains 4 photos.

Black-tailed jackrabbits (Lepus californicus) will eat almost any available green plant. Generally, jackrabbits eat more grasses and forbs (non-grass herbaceous flowering plants)  in the spring and summer while shrubs form the bulk of their winter diet. Recent heavy snows covered … Continue reading

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Another Early Arrival

This gallery contains 2 photos.

I recently mentioned two avian species that returned to our area this year much earlier than usual (red-winged blackbird 01-20-2017 and juvenile barn swallow 02-03-2017).  Leonard and I spotted another “early bird”, a single turkey vulture (Cathartes aura), on January … Continue reading

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A New Script??

This gallery contains 2 photos.

Barn swallows (Hirundo rustica) are long-distance migrants. After spending the breeding season throughout most of North America, they winter in Central America and South America. Barn swallows are one of the later swallows to return to our area in the … Continue reading

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