Anna`s Hummingbird - Neighborhood Naturalist

Transcription

Nature you can find in town and the nearby countryside
Corvallis, Oregon
Winter 2013-14
Anna’s Hummingbird
article and photography by Lisa Millbank
M
any of us brighten up the long, rainy months
of winter by feeding birds. Feeding Anna’s
Hummingbirds has become especially popular,
and these iridescent, sugar-fueled sprites enliven city and
suburban yards throughout the Willamette Valley.
Although Anna’s Hummingbirds are reliable local yard
birds today, that wasn’t the case 35 years ago. Remarkably,
these little birds were once restricted to southern California
and the Baja Peninsula. The introduction of eucalyptus
and tree tobacco probably helped Anna’s Hummingbirds
to spread throughout California and into much of the arid
Southwest. In the last few decades, Anna’s Hummingbirds
have colonized urban areas as far north as British Columbia.
In the Pacific Northwest, they rely on a combination of
hummingbird feeders and winter-blooming landscape
shrubs to survive the winter.
individuals may
actually migrate to
the Willamette Valley
from east of the Cascades.
The only other common hummingbird in the Willamette
Valley is the highly migratory Rufous Hummingbird. In
March and April, the arrival of the Rufous Hummingbird
marks a change in the lives of Anna’s Hummingbirds.
Though they’re slightly smaller, Rufous Hummingbirds
have a temperament to match their fiery colors. Though
Whether our local Anna’s Hummingbirds even migrate Anna’s Hummingbirds are quite aggressive themselves,
at all is mysterious. It’s clear that many are content to Rufous Hummingbirds often take control of feeders and
remain in the same place year-round. In the fall, some defend them fiercely. All hummingbirds are territorial, and
both Anna’s and Rufous Hummingbirds give squeaky “war
cries” when challenging others.
Sources of nectar, whether from flowers or provided
by humans, are worth defending, since a hummingbird
may eat several times its own weight in nectar in a day.
Very recent studies of Anna’s Hummingbirds have led to a
new understanding of the workings of the hummingbird
tongue. The tip of the tongue is forked, and each fork has
a fringe of thin plates called lamellae. When the tongue is
pushed into nectar, the tips separate and the lamellae open
outward. As the tongue is withdrawn, the lamellae curl
inward and trap the nectar so that it can be delivered into
An adult female visits a Red-flowering Currant bush in spring.
Neighborhood Naturalist, Winter 2013-14 v11 #4 • page 1
insight into the technique they use to catch flying insects.
Using high-speed cameras, researchers demonstrated that
a hummingbird doesn’t use the tip of its bill like tweezers
or chopsticks when chasing flying insects. Instead, as the
bird chases a fruit fly, it opens its bill wide and catches the
fly with the base of the bill.
It takes a lot of calories to power an Anna’s Hummingbird’s
supercharged metabolism, but cold winter weather and
long nights sometimes impose energy demands that it just
can’t meet. While it usually maintains a body temperature
These babies are about a week from fledging in a Corvallis park. of about 109°F, an Anna’s Hummingbird can enter a
Their nest is composed of lichens, mosses and spiderweb.
short-term hibernation-like state called torpor, where its
body temperature can fall to 48°F and possibly lower. Its
the mouth. Anna’s Hummingbirds drink nectar at about breathing rate can slow from 265 breaths per minute to
15 licks per second.
only one breath every five minutes. In this extreme state
of hypothermia, the hummingbird can greatly reduce
Flower nectar is rich in sugars, but hummingbirds get its need for food. Near sunrise, it begins to awaken and
their protein and other essential nutrients from tiny insects warm its body. Despite using this strategy, some Anna’s
and spiders. Most of these insects are gleaned from flowers, Hummingbirds still starve to death in the winter—some
foliage and branches, or even plucked from spiderwebs. just never wake up from torpor.
Sometimes, an Anna’s Hummingbird will visit one of the
sap “wells” created by a Red-breasted Sapsucker. Here, it
Though winter can take a toll on Anna’s Hummingbirds,
can find sugary tree sap and insects that have become stuck it’s also the time they begin to prepare for breeding. Unlike
to the sap. Captive Anna’s Hummingbirds have given us most hummingbirds, a male Anna’s Hummingbird sings
a long, complex song. Perched on a prominent twig, he
delivers a quiet, squeaky, scratchy jumble of sound, turning
Hummingbird feeder tips
his head left and right with his gorget and crown glinting in
• Make a solution of one part granulated white sugar
the sun. His singing activity will peak midwinter through
to four parts water; the 1:4 ratio approximates typical
spring, but he can sing any time of year. Hummingbirds
flower nectar. Boil the solution and let it cool to delay
spoilage.
aren’t true songbirds like American Robins or Song
Sparrows, for example, but experiments have shown that
• Don’t add red dye, vitamins or preservatives to your
the Anna’s Hummingbird has a similar song development
nectar solution, and avoid commercial nectars that
contain these additives.
process. Much like a young male songbird, a male Anna’s
learns to sing specific syllables and incorporate the correct
• Only use white sugar. Honey and other unrefined
sweeteners promote the growth of bacteria and fungi.
rhythms into his song by listening to adult males. It takes
Some sweeteners, such as molasses, brown sugar
a lot of practice for a young male Anna’s to perform the
and Sucanat, contain levels of iron that may be toxic
song correctly.
to hummingbirds.
• Wash and rinse the feeder thoroughly each time you
refill it.
• Hot weather causes nectar to ferment quickly, which
can sicken hummingbirds. It’s sometimes necessary
to change the nectar every other day.
• Nectar will begin to freeze at around 27°F. Bring
the feeder inside on cold nights and put it out again
before sunrise, or provide a heat source such as
an incandescent lamp or a length of plumbing heat
tape. Hummers Heated Delight is a small company in
Albany that makes heated feeders.
• Maintaining feeders for Anna’s Hummingbirds
throughout the winter is an important commitment.
They require fresh, thawed nectar every day, and their
lives depend on it during severe winter weather.
This male fans his tail, showing his
specialized outer tail feathers. Only
adult males have two thin feathers that
create a loud chirp during high-speed
display dives.
More dramatic is
the display dive that
males perform. While
the dive is courtshiprelated, a male may
do a series of dives
to intimidate other
males, or even when no
other hummingbirds
are present. Usually,
after a bout of singing,
he’ll rise from his
perch and hover for a
moment to sing a bit
more. Then, he slowly
Rufous Hummingbird
Adult male
Adult male
rose gorget
& crown
red-orange
gorget
green
back
gray &
green belly
An adult male Anna’s Hummingbird has iridescent rose
or magenta feathers on his throat (called a gorget) and
his crown. All of these iridescent feathers can look black,
yellowish or greenish in poor light. His back and the sides of
his breast are blue-green to yellow-green.
rufous &
white belly
An adult male Rufous Hummingbird has a red to orange-red
iridescent gorget, which can also look black, gold, greenish
or copper in different lighting conditions. His back, tail and
the sides of his belly are mostly rust-colored, or rufous. His
breast is white.
Adult female
green
back
rufous
back
Adult female
gray &
green belly
rufous &
white belly
no rufous
in tail
green
back
This adult female Anna’s Hummingbird is stretching. She’s
green overall, with a gray belly. She may have a patch of a
few iridescent rose feathers on her throat. Young males and
females look almost identical to adult females, and can be told
apart by the patterns on the tail feathers.
An adult female Rufous Hummingbird
has rufous on her flanks and portions of
rufous
her tail feathers. Her back is green. She
in tail
may have a throat patch of iridescent red
feathers. Young birds of both sexes resemble the adult female.
ascends to about 100 feet above the ground, looking as if
he’s being pulled by an invisible string. He hovers to sing
for a moment, then flies almost straight down, flapping 55
times per second. He reaches a speed of nearly 60 miles per
hour, tucks in his wings, and then, just as he’s about to hit
the ground, he spreads his tail to brake. As he fans his tail,
the passage of air over specialized outer tail feathers causes
them to emit a loud, sharp chirp, and he hurtles upward
away from the ground—only to repeat the whole process
several more times before resting or feeding.
female can accurately judge the genetic fitness of the males
she encounters by their iridescent plumage and the quality
of their displays. While most birds are monogamous,
hummingbirds are not, so Anna’s Hummingbird fathers
play no role in parenting.
A male Anna’s Hummingbird briefly endures about
10 g when he hits the brakes with his tail feathers. For
humans, acceleration over 5 g can sometimes cause loss
of consciousness, but small animals like hummingbirds
are more tolerant than we are. Nevertheless, a male
hummingbird must be in peak physical condition to pull
off dozens of these dives and tail-feather chirps every day. A
Female Anna’s Hummingbirds may begin nesting as early
as mid-January, but the majority probably start a month
or more later. In our area, a female typically uses mosses
and lichens to build a tidy cup, a little bigger than a large
walnut. She binds the nest together with swathes of spider
silk, giving the nest elasticity and strength. She also applies
small pieces of lichen to the exterior of the nest by sticking
Watch a video featuring
Anna’s Hummingbirds
www.neighborhood-naturalist.com
them to the silk, which provides excellent camouflage.
To line the interior of the nest, she searches for soft plant
fibers, animal hair or small feathers. The female usually sits
on the nest while she builds the sides, occasionally rocking
her body into the cup, which probably helps mold the nest
into the proper shape. She may use her feet to press the
soft lining into place.
Before she’s even done constructing the walls of her nest,
she may lay her two white eggs. An egg is slightly more
than half an inch long (slightly larger than a Jelly Belly
candy), and each egg weighs about half a gram. It takes a
little more than two weeks of incubation for the eggs to
hatch. The tiny creatures that emerge have short, stubby
bills and are naked, with a hint of fuzzy down. They look
like wriggling black raisins with a bit of lint stuck to them.
To power their rapid growth and development,
hummingbird babies require proportionally more protein
than adults do. A mother hummingbird feeds her babies
by inserting her needle-like bill deep into their crops and
regurgitating a semi-liquid mixture of small insects and
nectar. From dawn to dusk, she has the demanding task of
providing enough food for herself and two growing babies.
This immature male Anna’s Hummingbird resembles an adult
female, but he was already learning to sing and display dive. The
pattern on his tail feathers also distinguishes him from a female.
As the babies get older, their bills lengthen, they achieve
adult weight, and they grow a complete set of feathers.
Their spiderweb-and-lichen nest stretches to accommodate
both chicks. Finally, about 25 days after hatching, the
young hummingbirds take their first flights. Their mother
continues to feed them for a week or two after fledging, but
after that, they’re independent and ready to find a feeder
and a garden to claim as their own. Their mother will go
on to raise another brood.
A hummingbird garden
Hummingbird feeders keep Anna’s Hummingbirds going
through the winter, but also consider providing native
plants that attract hummingbirds and other pollinators
from spring through fall.
A few good choices include:
Red Columbine
(Aquilegia formosa)
Tall Oregon-Grape
(Berberis aquifolium)
Grand Collomia
(Collomia grandiflora)
Tall Larkspur
(Delphinium trolliifolium)
Pacific Bleeding-Heart
(Dicentra formosa)
Orange Honeysuckle
(Lonicera ciliosa)
Twinberry
(Lonicera involucrata)
Red-flowering Currant
(Ribes sanguineum)
Keep in mind that small insects and spiders are just
as important as nectar in the diet of a hummingbird.
Limiting your use of insecticides and encouraging a
balanced and diverse insect population in your garden
can help attract hummingbirds.
While all hummingbirds are both beautiful and
remarkable among birds, the Anna’s is a special one for
us. Only in the Pacific Northwest do hummingbirds
spend the winter this far north, and share such a close
relationship with humans. Next time you notice an Anna’s
Hummingbird this winter, remember the story of how a
desert bird came to the rainy Northwest, and the unique
biology behind this favorite backyard resident. ó
Bobcat
article and illustrations by Don Boucher
photography by Lisa Millbank
S
omehow, among common wildlife, Bobcats seem
extra wild and glamorous. Maybe it’s due to their
exotic appearance? I think Bobcats have another
appeal. They represent a part of the wild we can relate to
because they remind us, in part, of our pet cats.
I couldn’t see much, even through binoculars. It had the
gait of a cat and a short tail, so I assumed it was a Manx
cat from one of the nearby houses. Eventually I noticed
the large, black spots on its legs. Occasionally, it would
wiggle its flexible, short tail—an important observation.
When a domestic cat has a short tail, it’s stiff because it’s
I saw one this last fall. It was walking in a brushy, open missing most of the tail vertebrae. The wiggly tail swayed
area about 150 yards away. Since it was just after sunset, it heavily toward being a Bobcat. A few days later, Lisa and
I went back to the area and found the Bobcat again. This
time we got a closer look.
I’ve mistaken distant domestic cats for Bobcats before.
Domestic cats vary widely in size and appearance and
some do look a bit like a Bobcat. Even though Bobcats are
generally twice as large as domestic cats, it can be difficult
to judge the size of an animal from a distance. I’ve learned
to be skeptical of my initial assumptions. I’m also very
eager to see a Bobcat, and that can skew my perception.
What about the possibility of domestic cat/Bobcat
hybrids? Although it seems biologically possible, it’s not
likely even though there are a few reports of such hybrids.
Consider that cat breeders have developed exotic hybrids
of domestic cats and wild cat species from Asia, Europe
and Africa. There’s a market for wild-looking cat hybrids.
If Bobcat/domestic hybrid cats were feasible, they’d be on
the market. They’re not. Because of this, Bobcat/domestic
hybrids occurring in the wild may be practically impossible.
This female Bobcat and her kitten live in a wetland on the outskirts
of Corvallis. The male at the top of the page lived in a Corvallis park.
Watch a video featuring
Bobcats
Interestingly, among
American native cats,
Cougars are the most
clo sely related to
domestic cats.
Hybrids between
Bobcat and lynx
are possible because
Bobcats are lynx. In
Oregon, there are
very small numbers
This kitten is about five months old, of Canada Lynx in the
and follows its mother as she hunts. The Cascades and in the
mother is on the previous page.
mountains to the east.
Remarkably, there was
a well-documented report of a Canada Lynx in North
Albany more than forty years ago, but don’t expect to see
one in the Willamette Valley. Consider yourself lucky if you
ever see a wild one at all, even in their mountain habitat.
But Bobcats are widely common in Oregon, including the
Willamette Valley.
Like all other lynx, Bobcats’ favorite prey are rabbits and
hares, but the diet of any given Bobcat depends on how big
it is, the prey available and its particular hunting skill set.
They hunt mostly at dawn and dusk, and take on anything
from mice to deer. Unlike many pet cats, Bobcats have an
affinity for water, hunting fish, ducks, Nutria and Common
Muskrats. Their long legs make them excellent leapers,
capable of hunting birds. Some Bobcats specialize in the
tricky business of hunting North American Porcupines. The
largest males can even kill deer by catching them by the
throat, but this is uncommon, and Bobcats typically hunt
prey smaller than themselves. They can also scavenge deer
and elk that have been killed by larger predators.
A Bobcat generally depends on wild prey with which
it’s become familiar. Bobcats are intelligent and adaptable
hunters, and some do learn to take chickens and small pets
from yards. There are many simple and effective measures
to protect domestic animals. Providing secure fences and
chicken coops and keeping domestic cats indoors will
eliminate most Bobcat predation. Bobcats are afraid of
dogs, so the mere presence of a medium or large dog is
often enough. Bobcats pose no threat to humans, and in
the balance of human/Bobcat conflicts, Bobcats are at a
heavy disadvantage.
Bobcats vary greatly in appearance over their continentwide range. In some regions, Bobcats’ coats may be covered
with heavy spotting, but our local Bobcat subspecies tends
to have a dark coat with reduced spotting on the back and
sides. Some individuals have stripes on the back, while
others have almost no markings on the back at all. The size
can vary as much as the coat pattern. Although published
weight ranges state that Bobcats can weigh anywhere
from nine to almost 70 pounds, these figures represent
the entirety of all Bobcat subspecies. Our western Oregon
subspecies falls somewhere in between, with few males
exceeding 35 pounds. Within a population, female Bobcats
are noticeably smaller than males.
In our area, Bobcats hold territories ranging from about
two square miles to over a dozen square miles. The size of
the territory depends on the sex of the Bobcat, the habitat
and the density of prey. A Bobcat doesn’t defend its territory
as if there were an invisible fence around it. Instead, each
Bobcat maintains a cluster of preferred hunting, denning
and watering spots. In general, a transient Bobcat may enter
another Bobcat’s territory without conflict, so long as one
of the territory owner’s cherished spots is not encroached
upon. Males tend to be a little more lenient with visitors
than females. Conflict is hardly ever necessary, because the
resident’s scent marks (from urine, feces and anal glands) are
often enough to discourage an intruder. A male has a larger
territory than nearby females, and because he’s not involved
in the rearing of kittens, he can wander more freely. His
territory overlaps with nearby females’ territories, and may
extend into another male’s area. A female’s territory doesn’t
overlap with the domains of neighboring females, and a
mother with young kittens has very limited mobility.
Bobcats live in a variety of forested and open habitats.
They like rocky outcrops and south-facing, open slopes
if available. They live just about any place where there’s a
few square miles with low human activity and ample prey.
Try to spot Bobcats along the edges of undisturbed open
fields. You can also look for the signs they leave, like tracks,
scat and scratching posts (see Bobcat sign illustrations and
photos on the back page). Keep a sharp, discerning eye out
A Bobcat’s tail is not particularly short. It’s about a third as long and you may encounter one of the most alluring of our
as a domestic cat’s tail (relative to body length).
wild neighbors. ó
Bobcat
A Bobcat’s tail is flexible
and expressive.
The back legs
are longer than
the front. When
walking, the hips
sway and bob.
Longer legs
(relative to body
length) than
Cougars or
domestic cats
Domestic cat
If a domestic
cat has a short
tail, it’s stiff
and stout.
Domestic cats come in different sizes, shapes
and colors and can have Bobcat-like markings,
including short tails, spots and ear tufts.
Domestic cats have shorter legs.
A large domestic cat can approach the size of small adult female Bobcat.
Size comparison
Cougar
Canada Lynx
Not present in the Willamette
Valley or Coast Range.
Bobcat
Cougar
Bobcat
Rear
Coyote, Red Fox and dog
tracks show claw marks
(Common Gray Fox tracks
usually don’t). Unlike
cats, when canines walk
in a soft substrate, the
track shows a peak in the
center.
Domestic
cat
Rear
Coyote
Rear
3–4¾”
Front
Rear
Front
Front
1–1¾”
Front
1½–2½”
Tracks shown about ½ size
In this illustration, the rear tracks lie in front of the
front tracks. This is a common pattern called an
overstep gait. More common is a direct register gait,
where the rear track falls on top of the front.
Above: This Mallard was killed by a
Bobcat living in a wetland in Corvallis.
Right: A Bobcat near Philomath used this
cherry tree as a scratching post.
Bobcat scat is typically segmented and about twice the size
of a domestic cat’s scat. Coyote scat can look similar, but
is usually twisted and may contain fruit seeds and skins.
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Corvallis
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Come learn or share your knowledge about nature in the Willamette Valley. We look at birds,
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Anna`s Hummingbird - Neighborhood Naturalist

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