Note: If you’re interested in monthly information about Washington's wildlife and WDFW’s Backyard Wildlife Sanctuary Program, you can “e-subscribe” to our “Crossing Paths with Washington’s Wildlife” news notes at http://wdfw.wa.gov/lists/ . As an e-mail subscriber to “Crossing Paths,” you’ll receive these news updates automatically in your e-mail inbox, without linking to a download. As always, you can easily unsubscribe by following the instructions on our WDFW Mailing Lists website. We hope you find these news notes timely and useful. If you have any questions, please contact Madonna Luers at Madonna.Luers@dfw.wa.gov
Subscribe to "Crossing Paths"
e-mail news notes today!
|Even amidst fully-leafed-out trees at this time of year, it's hard to miss a great blue heron (Ardea herodias). - Bill Anderson photo
By Jamie Bails, WDFW habitat biologist
Even amidst fully-leafed-out trees at this time of year, it's hard to miss a great blue heron (Ardea herodias).
Four feet tall with a six-foot span of blue-feathered wings, this big bird is mostly beak, neck and legs. It's commonly found in both rural and urban areas of every Washington county and can be even more noticeable in the spring and summer because it nests communally, in large groups called heron rookeries or colonies.
Although widely recognized, much is still unknown about foraging, seasonal dispersal, habitat associations and winter distribution of the great blue heron. Many eastern Washington herons migrate south in the fall, but others, especially on the west side of the state, are year-round residents.
The non-migratory Puget Sound population is classified as a sub-species (Ardea herodias fannini) found only in the Salish Sea, a broad area that stretches from Prince William Sound to south Puget Sound. What we DO know is that these herons are an important indicator of the health of Puget Sound.
According to "Great Blue Herons of Puget Sound," a technical report by Ann Eissinger published by the Puget Sound Nearshore Partnership, 49 percent of this population is concentrated in four mega-colonies of 200-600 heron pairs. The remaining 51 percent is in small to medium colonies of less than 200 pairs, scattered along the Puget Sound shore from Bellingham to Olympia.
Many of the largest nest sites are in northern Puget Sound near eelgrass beds on marine shorelines, like the March Point colony in Padilla Bay, where several dozen herons are frequently seen wading to feed on herring, shrimp, crabs, sculpins, starry flounder and other aquatic life.
In south Puget Sound, where eelgrass is not abundant, smaller colonies are distributed by tree availability, access to marsh foraging areas and prey abundance. These smaller southern colonies usually breed earlier than those of the north and Strait of Georgia.
Based on Eissinger's observations over 25-plus years, some mega-colonies appear to fragment, with herons relocating to new and existing nesting sites, usually closer to productive marine feeding areas.
For example, a Point Roberts colony of nearly 400 nesting pairs began to fragment in 2002-2003, with about 350 pairs moving about two miles north to the Tsawassen bluff, directly above their primary feeding grounds at Roberts Bank. Another case was the Birch Bay colony of about 275 nesting pairs, which fragmented and relocated between 2006 and 2008 to a new site at Drayton Harbor with about 100 nests, and to the Lummi Bay colony, which grew by 50-100 nests.
Most great blue herons begin the reproductive cycle in early February, gathering at these traditional communal nest sites. These sites are usually in tall deciduous trees such as alder, cottonwood and big leaf maple, but also cedar, hemlock and pine, and near foraging habitat like an estuary or other waterway.
By March the male of each pair is providing sticks for the female to build a nest or renovate an old nest. She lays three to five eggs, and both take turns incubating them for almost a month. By the end of May the eggs begin to hatch, and chicks grow rapidly, fed by both parents. The chicks first leave the nest at 7-8 weeks but usually return to be fed for another few weeks.
| Just this month these three of six great blue heron fledglings were found on the ground near a Puget Sound colony, some injured and all unable to fly. They are currently under the care of state licensed wildlife rehabilitators at the Lynwood-based Progressive Animal Welfare Society (PAWS) and will be released later this year when they are able to make it on their own.
By the end of September, the juveniles have fully fledged and disperse with adult females to upland rivers, lakes and wetlands to find prey. There they stay through the winter, roosting nightly at forest edges on lateral branching trees. Voles and other small mammals, reptiles and amphibians provide easy and abundant food around fields and marshes, and winter-returning salmon are taken from rivers and beaver ponds. Adult male herons maintain their shoreline territory over winter.
Puget Sound's mega-colonies of great blue herons act as an anchor for an overall resilient population, but by being concentrated they are susceptible to disturbance, both natural and man-made.
For example, in the 1990's a large ice storm destroyed the colony at Squaxin Island near Olympia, killing all the nest trees. If a major oil spill were to occur in Padilla Bay, the largest heron breeding center in the Salish Sea -- March Point and Samish Island colonies -- could be seriously impacted.
Smaller colonies might be at greater risk of competition with other species or predation. At Edmonds Marsh, herons have tried to establish nests over the last dozen years, but fledglings have not yet been documented. Many heron-watchers assume nearby mature bald eagles are thwarting the herons' efforts.
On the other hand, a bald eagle nesting pair near several heron nests at Point Roberts is more likely protecting both species' territory from raids by crows, ravens or immature eagles.
Over the years, heron watchers throughout Puget Sound have seen both large and small colonies shrink, grow, and completely disappear. In 2010, the Kiwanis Ravine colony included some 80 successful nests, but by 2014 there were none.
The now abandoned Black River colony in Renton once supported 130 nests. Today the Lake Sammamish State Park and Kenmore Park & Ride colonies are the largest in the Pierce/King/Snohomish county area.
Eissinger has noted that many Puget Sound herons are well-adapted to human disturbance, including dogs, motor vehicle traffic, and industry noise. Nevertheless, heron colony watchers need to keep a respectful distance from nests. Keep pets on leash, minimize noise, and bring binoculars, scopes and telephoto camera lenses to enjoy these big birds.
|Western hemlock (Tsuga heterophylla), Washington's state tree, is favored by elk and deer for its delicate feathery foliage, and juncos, siskins, chickadees and squirrels for its seeds.
April is the month of Arbor Day and Earth Day, and this year both are promoting something we advocate for wildlife habitat -- tree planting.
Arbor Day has always been about planting trees, starting in 1872 in Nebraska and officially celebrated nationwide on the last Friday of April. Washington state traditionally celebrates Arbor Day the second Wednesday of the month, April 13 this year.
Earth Day began on April 22, 1970 at the start of the movement when the Environmental Protection Agency (EPA) was formed and the Endangered Species Act and other environmental laws were passed.
This year's Earth Day theme is "Trees for the Earth -- Let's get planting!" This effort will continue over the next four years with a national goal of planting 7.8 billion trees by the 50th anniversary of Earth Day in 2020 to help combat climate change.
How can something as simple as a tree address something as complex as climate change? Trees absorb excess and harmful carbon dioxide in our atmosphere. In a single year an acre of mature trees absorbs the same amount of carbon dioxide produced by driving the average car 26,000 miles.
Trees help us breathe clean air by absorbing odors and pollutant gases (nitrogen oxides, ammonia, sulfur dioxide and ozone) and filtering particulates out of the air by trapping them in their leaves and bark.
Trees save us energy, up to 30 percent in cooling costs when properly planted around a house to shade sunny south and west sides. They can provide food and income, too.
And of course trees are critical to wildlife, providing nesting sites, roosting spaces, escape cover, and food for a diversity of native mammals, birds, reptiles and amphibians, and invertebrates like butterflies and moths.
So let's get planting!
Tree species native to Washington are your best bet, not only for native wildlife but for ease of care and long-term sustainability. The following are among good choices, depending on your landscape:
- Big-leaf maple (Acer macrophyllum) is a fast-growing tree suited for large landscapes that provides homes for cavity-nesting birds and food for insectivorous birds like woodpeckers and nuthatches.
- Douglas maple (Acer glabrum douglassii) is a small tree used for its seeds by grosbeaks, quail and grouse, for its twigs and bark by deer and beavers, and as a larval host for some moth species.
- Vine maple (Acer circinatum) is best suited for westside landscapes where it grows naturally in groups as large understory shrubs or small trees. It's a larvae plant for brown tissue and polyphemus moths, a good nectar source for bees, and seed-producer for a variety of birds.
- Oregon white oak or "Garry oak" (Quercus garryana) is a thick-limbed, long-lived tree that is Washington's only native oak. Like all oaks, it produces acorns loved by everything from Clark's nutcrackers to tree squirrels, and at maturity they often provide cavities for nesting and roosting by both birds and mammals.
- Pacific dogwood (Cornus nutallii) has large, creamy-white, showy flowers eaten by spring azure butterfly larvae. A diversity of birds, including bluebirds, sapsuckers, white-crowned and song sparrows, tree swallows, towhees, and vireos eat its fruit.
- Cascara (Rhamnus purshiana) is a native small tree or tall shrub that grows well in disturbed sites. Its berries are eaten by grosbeaks, grouse, jays, robins and tanagers, as well as bears, foxes, coyotes and raccoons.
- Native birches (Betula spp.) are hardy clump-growers to plant far from drain pipes or foundations, but they produce lots of wildlife habitat: seeds for juncos, siskins and other birds; insects for kinglets, warblers and other birds; bark for nesting material; leaves for mourning cloak and swallowtail butterfly larvae; twigs for elk, deer and small mammals; cavities for birds and other wildlife.
- Native hawthorns (Crataegus spp.) are more shrub-like than tree, with densities that often provide good escape cover for songbirds. Berries are favored by robins, waxwings, wood ducks, turkeys, black bears, coyotes and foxes, to name a few.
- Native pines (Pinus spp.), which can be fast-growing large trees best suited for larger properties, provide nesting sites for many songbirds and seeds for, among others, crossbills, mourning doves, jays, finches, siskins, and chipmunks.
- Douglas-fir (Pseudotsuga menziesii) grows quickly with a dense screen of soft needles that are used by silver-spotted tiger moth larvae, among others; its seeds are eaten by grouse and many songbirds, its associated insects are eaten by brown creepers and woodpeckers, its twigs are browsed by deer and elk; at maturity its cavities harbor flying squirrels and other animals.
- Western hemlock (Tsuga heterophylla), Washington's state tree, is favored by elk and deer for its delicate feathery foliage, and juncos, siskins, chickadees and squirrels for its seeds.
Lots more detail about these and many other trees for wildlife is available in the book by WDFW wildlife biologist Russell Link, "Landscaping for Wildlife in the Pacific Northwest" (http://wdfw.wa.gov/living/book/index.html .)
Certified arborists are excellent professional resources on tree planting, care, and maintenance, and can be found through the Pacific Northwest chapter of the International Society of Arboriculture (http://www.pnwisa.org/.)
For more information about Arbor Day, including details on how to properly plant a tree, see http://www.arborday.org.
For more information about this year's Earth Day campaign, see http://www.earthday.org/2016/ .
|Landscape designed to provide habitat for birds, bees, butterflies and other animals.
Gardeners have been daydreaming over seed catalogues since New Year's, but with actual Spring finally within sight now, it's time to place orders and make those dreams come true.
Those who also garden for wildlife will want to keep the birds, bees, butterflies, and other animals in mind when making those seed and plant selections.
Lots of varieties of annuals and perennials, plus garden vegetables, can provide food for wildlife with nectar-producing blooms and/or attract pollinating insects that become part of the food chain for others.
So how do you choose from all those enticing catalogue pictures and listings?
Washington Department of Fish and Wildlife (WDFW) biologists recommend using local native plants when you can, or non-natives if they're not invasive in your local area.
"Don't choose hybrids with double flowers because the flower structure may prevent flying insects from gaining access to nectar or may even have nectar-production bred out," said WDFW's North Puget Sound regional wildlife program manager Russell Link.
WDFW's Backyard Wildlife Sanctuary program information (available at http://wdfw.wa.gov/living/backyard/ ) includes some specifics about plant choice to benefit wildlife, like hummingbirds and butterflies. These include both local native and non-native plant species, but natives are usually best.
Links says plants that are native to local habitat in Washington are best suited for our soils and climate so they usually grow more easily. By nature of being native, they have the potential to be truly "sustainable".
The appropriate native plant usually require less care, especially watering, once they are established. And most important to wildlife enthusiasts, many native plants are more readily used by the native wildlife with which they evolved.
Plant and seed catalogue companies from across the country may include species "adapted to the Northwest," but remember that is not the same as "native to the Northwest."
Thanks to increasing interest in "sustainability," sources of native plants and seeds are increasing in Washington. The Washington Native Plant Society (WNPS) provides a list of nurseries by county that sell native plants and seeds (see http://www.wnps.org/landscaping/nurserylist.html.)
Whether you go native or use non-invasive exotics, keep those pollinators in mind.
"I buy a lot of "six packs" from a local nursery," Link said, "and when shopping, I'll give the flats of flowers a little shove to see what flies off. Some flowers, like Sweet allysum, will produce a flurry of of flying pollinators."
Link also notes that most vegetables are pollinated by flying insects.
"I grow scarlet runner beans because they have attractive red flowers, are tasty, and attract bumblebees and hummingbirds," he said.
Some plants pollinated by insects specifically attract night-flying moths that provide food for bats, including Sweet William, Fireweed, Honeysuckle, Bee balm, Mock-orange and Yucca. Bats Northwest has more information on moth-friendly plant species at http://www.batsnorthwest.org/attracting_insects.html .
Link's book, "Landscaping for Wildlife in the Pacific Northwest," is a good source of further information on plant choices for the wildlife garden. For more details on how to purchase this reference, see http://wdfw.wa.gov/living/book/index.html .
|Now is the time to get your bird nest boxes cleaned out and ready for new, incoming occupants..
Spring may officially be several weeks off, but now is the time to get your bird nest boxes cleaned out and ready for new, incoming occupants.
If you don't already have nest boxes up, this is the time to either build or buy and place them, following our specs at http://wdfw.wa.gov/living/projects/nestboxes/index.html.
Many backyard birding enthusiasts who use nest boxes leave them up year-round and leave nesting materials in them through the winter, when some birds will use them as nightime roost sites.
But migrating birds that use cavities for nesting, like bluebirds, swallows and wrens, will be returning next month and they prefer clean quarters to follow their instincts to build their own nests.
All nest boxes attract insects – mites, lice, fleas, flies, hornets, spiders and more. In small numbers they are relatively harmless to birds, but in larger numbers they can cause injuries and even fatalities to young birds.
Inspect all nest boxes to clean out insects and also to remove the old nesting material. Although some diligent and industrious birds will remove old nesting material before building their own particular nest, many more will just build on top of an old nest. That kind of layering can raise the nest dangerously close to the entrance hole where predators might reach eggs or young.
Your inspection may turn up dead nestlings or infertile eggs, which of course should also be removed. Be sure to use protective gloves, maybe even a dust mask, and dispose of everything you find in nest boxes away from the site to avoid smells that can attract predators.
Nest box maintenance includes tightening screws, loosening lag bolts, unblocking drainage holes, and generally making sure everything is secure and working right.
If you find a nest box in your collection that year after year goes unused, consider relocating it. It might not be in the appropriate habitat or suitable height location for the species it's built for, or perhaps it's in the right place but is not built correctly. Check the entrance hole size, overall size dimensions, and other factors that are important to, and different for, various species of nest-box-using birds. Details are available at http://wdfw.wa.gov/living/projects/nestboxes/index.html .
If the same nest box turns up dead nestlings or infertile eggs more than once, consider relocation to avoid competitors or predators, or remodeling to protect the species using the box. A predator block – just a one-inch thick piece of wood drilled with the appropriate size hole – mounted over the entrance hole to create a short tunnel into the nest, can deter starlings, raccoons, or squirrels that have chewed the original hole bigger.
Another improvement is to remove any perch post projecting out from the front of a nest box. Our native cavity-nesting birds don't need these perches but they are used by more aggressive non-native birds to harass nesting birds.
If you often have earlier-arriving starlings or English house sparrows dominating your nest box site, you may want to plug the entrance hole until later this spring when martins or swallows or other native species arrive. Small paper cups and other such plugs work well. Remember to remove the plug as soon as you see your "target" species return to the area, or when you otherwise learn of its return to your area. (Online birding chat groups can be a good source of news about migratory bird movements.)
If you watch a nest box closely enough this spring to know when birds have finished raising a brood, you can clean out the box again to encourage another pair to use it or the same pair to nest again. Just don't bother an obviously occupied nest box.
|It's the most common forest feline that we never get a chance to see -- the bobcat (Lynx rufus).
By Jamie Bails, WDFW habitat biologist
It's the most common forest feline that we never get a chance to see -- the bobcat (Lynx rufus).
My chance came on a drizzly morning in late October on a hike near Skykomish. We drove up the long, gravel road to an empty trailhead, complaining about the rain and missing the spectacular view. But a hike in the rain meant solitude in the Wild Sky Wilderness, so we donned raincoats and loaded backpacks with camp stoves, trail mix and packets of tea.
We went up the steep trail, chatting while our dogs stayed close by. Clearing another switchback, the path leveled out as we approached a south-facing ridge covered in young alder.
Suddenly my friend's dog jumped off the trail into the thick brush, sniffing the base of an old spruce tree. Stopped in our tracks, I heard her whisper "It's a bobcat!"
Just 20 feet away, balanced on the end of an alder branch, he sat, eyes wide open, staring at us, his mouth opening wide to hiss us away. Four paws tightly gripped the thin, bending branch, but his body was perfectly balanced in the air, like a walker on a tightrope. His body arched, thick fur standing on end, posed for escape.
I could barely see his eyes through the drizzly haze, but he did not blink. For a long minute I stared at him through the mist, holding my breath as I watched a wild cat in a tree, the first wild cat I had ever seen.
While bobcats are considered common enough in Washington to be classified as a small game and furbearer species that can be hunted and trapped, few people see them. As stalking predators they make it their job not to be seen. And if they are spotted, they disappear as quickly as they came, leaving you wondering if you ever saw it at all….
Bobcats, a close cousin of the Canada lynx (Lynx canadensis), are widely distributed over North America, ranging from southern Canada through the continental U.S. to southern Mexico. They are found in all habitats, from boreal forests to coniferous mixed forests, hardwood forests, coastal swamps, deserts and scrublands.
In Washington, bobcats are generally found below 4,000 feet elevation, mostly in wooded areas with escape cover, including suburban areas. In western Washington adult males have a home range of two to six square miles, half that for females. Eastern Washington bobcats have larger home ranges.
A male will mate with each of the several females who overlap his territory, and females will mate with several males. Each female may raise between two and four kittens a year depending on prey availability. The kittens are born in the spring and stay with mom for nine to 12 months, learning to hunt for themselves until they naturally disperse in late fall or early spring.
Bobcats are most active at dusk and dawn, hunting by sight and sound, watching and listening while perched on a stump or behind a tree, their spotted coats blending neatly with forest.
That spotted coat varies widely in color from tan to grey to reddish, as is more common on the west side of the state. They are named for the short bob tail, only up to six inches long, painted with black stripes at the top and bottom. Their back legs are longer than the front, which enable long leaps up to ten feet, and thick paws cushion the landing when they hit the ground. Males are larger, weighing up to 30 pounds and measuring over two feet long. Bobcats tend to be larger in the north and typically live 12-15 years in the wild.
The bobcat is an adaptable hunter, preying on anything from voles to rabbits to mountain beaver; it will even take prey twice its size. Once prey is sighted, bobcats stalk for a short distance, moving stealthily through the forest by placing their back paws in line with the front, followed by a quick leap and pounce on to the prey. If the prey is large, like a sick or weak deer, they stash it, covering it with brush and revisiting it until the prey is consumed. In suburban areas, bobcats may occasionally take a weak or sick, feral or domestic animal, but that is not typical.
Bobcats even share a prey species with their rare Canada lynx cousins – both cats hunt snowshoe hares. Bobcats aren't as well suited for deep snow conditions as lynx, which have longer legs and bigger, snowshoe-like feet. But over time, the smaller bobcat has adjusted to varying food and habitat conditions, surviving as more of a generalist in areas where the lynx cannot. As the climate changes and snow levels recede, the survivalist bobcat may take on territory and ranges once inhabited by the lynx.
The bobcat's curious nature often leads it into traps, says Brian Kertson, Washington Department of Fish and Wildlife (WDFW) carnivore specialist and researcher. In a cage trap set to catch a cougar for radio-collaring, he often finds a bobcat feeding on a free meal. Using a stick, he coaxes the bobcat out of the trap and resets it for the cougar. "The bobcat is full of piss and vinegar," he says, "and not easily discouraged from traps."
Bobcats spend the day sleeping in secluded hollow logs, stumps or brush piles, avoiding contact with other mammals, being solitary and unsociable. As I saw, they climb trees with ease when inadvertently disturbed.
Continuing up the trail, we quietly left the bobcat to return to its daytime sleeping spot, huddled inside the roots of that old spruce tree, awaiting dusk to search for a nighttime meal.
Finding a bobcat to experience an encounter like this is a long shot. But this winter, no matter the weather, take a long walk on a forgotten trail along the forest fringe, and don't be surprised if a bobcat finds you first.
To learn more about bobcats in Washington, see http://wdfw.wa.gov/living/bobcats.html