Monarchs by Kate Redmond
By Kate Redmond
Ecologically speaking, putting almost all of your eggs in one basket is a really bad idea.
Quick review: Monarch butterflies (Danaus plexippus) feed on a variety of flowers but lay their eggs only on plants in the milkweed family. The bright, aposematic (warning) colors of both the butterfly and its caterpillar alert potential predators to back off. (Poisonous milkweed sap renders the caterpillar toxic, and it carries its toxicity into adulthood.)
Monarchs migrate. Let’s unpack that simple, two-word sentence, because the biology behind it is complicated (and miraculous), and whole books have been written about it.
There is a Pacific population of Monarchs that migrate only as far as southern California in winter (though some free spirits have wandered as far as Hawaii and beyond), and there are year-round breeding populations in the Florida peninsula and along the Rio Grande. Historically, all of the migratory Monarchs east of the Rockies overwintered on a dozen or so smallish sites in the oyamel fir forests of the Central Highlands northwest of Mexico City.
Monarchs usually return to Wisconsin by mid-May. Researchers don’t know whether the late migrations recorded in the past few years are random events or are due to climate change. Once they get here, there are several short-lived generations that serve to produce more Monarchs, but in mid-August, a generation is produced that uses its energy to migrate rather than to procreate. This final brood, called the Super-generation or Gen 5 (the fifth generation removed from Mexico), is exceptionally long-lived and is the only generation that is tagged for migration studies. Experiments suggest that “host plant quality” (Monarch caterpillars prefer tender, young leaves, not the leathery plants of late August), decreasing day length, cooler overnight temperatures, and the changing tilt of the earth combine to flip a switch in the Monarch’s brain (which is about the size of the head of a pin). Wherever Monarchs are, they are cued to start moving south when the sun recedes to around 57 degrees above their southern horizon. (They migrate along the shore of Lake Michigan.) They navigate using an internal “sun compass” that allows them to adjust their orientation in relation to the sun’s movements across the sky, and they probably also sense magnetic fields with their antennae. This allows Monarchs in Michigan, Maine, and Montana to set correct (but different) flight plans for central Mexico.
The butterflies move south in the fall, spending the winter some 1500 miles south of Wisconsin. Monarchs eat little on their wintering grounds, depending on fat reserves built up during their leisurely migration. (A newly emerged butterfly has about 20 mg of fat in its body, but a Monarch newly arrived in Mexico carries 125 mg of fat.) In spring, signaled by warming temperatures and the availability of milkweed, Monarchs become reproductively ready and head back north, being careful not to outpace the emerging milkweed plants. They lay eggs in the southern tier of states, and their offspring continue the journey.
The spectacle of Monarch butterfly migration is one that inspires international awe (and, not surprisingly, sometimes-invasive ecotourism), and the drastic decline in Monarch numbers over the past decade has resulted in quite an outcry. Some numbers: In the mid-1990s, an estimated one billion Monarchs migrated to central Mexico, with another million counted in California. Today, the entire population is estimated at 56.6 million—a decline of more than 80%. (A 2013 World Wildlife Fund count was 33 million.) During the winter of 1996-97, wintering butterflies covered 21 hectares (one hectare is just under 2.5 acres). In 2013-14, they occupied only two-thirds of one hectare of forest, and 80% of the butterflies were found on just a few sites. Predictions for this year, if all the ducks stay in a row, are more optimistic, but far from rosy.
What’s happening? In a nutshell:
WEATHER AND CLIMATE:
Monarch survival depends on favorable weather in their summer range, during migration, and on the wintering grounds. The extreme weather events associated with climate change will affect Monarchs negatively—cold, wet winters; a warmer climate in Mexico that may negatively impact the oyamel fir trees; large storms or stubborn frontal systems at the start of the spring migration; and prolonged heat and drought that shorten the blooming periods of flowers (and therefore the availability of nectar), especially in plants that the butterflies depend on during migration. (Remember 2012, when even the prairie plants looked wilted?)
It’s cold up in the mountains, but wintering Monarchs can tolerate cold temperatures if they’re dry, and they burn fewer calories idling in cool weather. Rain or snow that wets the butterflies, followed by freezing temperatures, are a one-two punch, especially in January and February, when butterfly thoughts are turning northward and their fat supplies are waning. In the winter of 1995, snowstorms on the wintering grounds caused greater than 60% mortality. As the butterflies headed north in the spring of 1996, el Nino delivered heavy rains in the southeastern United States, and more died. In 2002, 2004, and 2010, huge Pacific weather systems brought heavy rain, hail, and frigid air into the wintering areas, decimating the Monarch population. The 2002 storms resulted in a 75% casualty rate.
Although the Mexican government has banned logging in the area, illegal logging continues to nibble away at the oyamel forests, which affects the microclimate created by the trees’ canopy and allows greater temperature fluctuations within the forests. The trees are also threatened by bark beetles. North of the Rio Grande, commercial-urban-suburban development is replacing Monarch habitat at a rate, according to one source, of 2.2 million acres per year (6,000 acres a day). The biofuel movement accounts for some of this loss, with land being taken out of the Conservation Reserve Program to produce corn to make ethanol. The tricky part, of course, is balancing the needs of the Monarchs and the needs of the people who live in the area.
The Corn Belt produces more than half of the Monarchs that migrate to Mexico. Common milkweed (Asclepias syriaca) is their food of choice, but common milkweed is disappearing, largely due to today’s agricultural practices. Crops like corn and soybeans are genetically modified so that they can survive exposure to herbicides like Roundup, allowing farmers to spray more often. (Crops are in the works that will have multiple resistances.) Sprayed chemicals often drift past the borders of agricultural fields, and roadside flowers become collateral damage. Neonicotinoid insecticides kill agricultural pests, but innocent bystanders are also exposed to this neurotoxin when they nectar on adjacent wildflowers.
The clean farming trend that advocates removing fence rows and non-agricultural vegetation between cultivated fields leads to the loss of native plants and wildlife, and roadside mowing takes a toll, too. Milkweed is slow to regenerate, and one study suggests that 60% of milkweed has been eliminated from the grassland ecosystem in the Midwest (http://www.mlmp.org/results/findings/pleasants_and_oberhauser_2012_milkweed_loss_in_ag_fields.pdf). The tricky part, of course, is balancing the needs of the Monarchs against our desire for inexpensive food.
Ophryocystis elektroscirrha (OE) (http://monarchparasites.uga.edu/whatisOE/) is a protozoan parasite that infects only Monarchs and the related Queen butterflies. One theory is that Monarchs pick up the protozoan from the leaves of tropical milkweeds that don’t die back in the winter and so have a longer period to harbor the parasite and its spores. Female Monarchs pass it on to their eggs and to the plants they land on, and caterpillars ingest it as they feed. Most of the damage is done during pupation, and emerging adults are covered with spores. Infected adults may simply be less fit (the long migration south is Darwinian natural selection in action), but a heavily infested Monarch may have difficulty emerging from its chrysalis and may have deformed wings. OE was first noted in South Florida and has been around for almost 50 years, and although it’s been found in all of the populations of Monarchs, the highest rates of infection are found in non-migratory groups (reaching 70% in South Florida). The infection rate in eastern migratory Monarchs is between 7% and 8%.
There were three hurricanes and two tropical storms at the start of the 2017 fall migration period https://monarchwatch.org/blog/2017/09/15/forgotten-victims-of-harvey-the-pollinators/.. The fall migration of 2017 along the Atlantic Coast was late, with some butterflies lingering into late October and even early November, lulled by unseasonably warm weather, the late migrants left susceptible to storms and freezes.
Chip Taylor at Monarch Watch (https://monarchwatch.org/) issues frequent updates about Monarch populations. As of March 18, World Wildlife Fund Mexico in collaboration with CONANP and the Monarch Butterfly Biosphere Reserve, announced the total forest area occupied by overwintering Monarch colonies. Nine colonies were located, with a total area of 2.48 hectares, a 14.77% decrease from the previous season.
He also says, “we need a comprehensive plan on how to manage the fragmented edges and marginal areas created by development and agriculture since it is these edges that support Monarchs, many of our pollinators, and the many forms of wildlife that are sustained by the seeds, fruits, nuts, berries, and foliage that result from pollination.”
The plight of the Monarch has energized people and organizations across the country. The Monarch Butterfly Biosphere Reserve, which contains most of the overwintering sites, was created in 1980 and declared a World Heritage Site in 2008. The International Union for Conservation of Nature declared Monarch migration as a Threatened Phenomenon, and the US Fish and Wildlife Service is considering adding Monarchs to the Endangered Species list. Monarchs are expected to benefit from the 1,500-mile-long “Butterfly Highway” proposed by President Obama as part of his efforts to help native pollinators (http://www.csmonitor.com/Environment/2015/0522/How-Obama-s-butterfly-highway-paves-way-to-save-embattled-monarchs).
The Monarch’s population plunge has been publicized by (among others) the National Wildlife Federation, the Defenders of Wildlife, the Xerces Society, World Wildlife Foundation, USDA Natural Resources Conservation Service, the Natural Resources Defense Council (suing the EPA over pesticide regulations), and a whole bunch of newspapers and periodicals. The US Fish and Wildlife Service is committing $20 million for habitat restoration over five years. The Monarch Joint Venture (http://www.monarchjointventure.org/) is a partnership of federal and state agencies, non-governmental organizations, and academic programs working together to support and coordinate efforts to protect the Monarch migration across the lower 48 United States. And there are many grassroots organizations.
WHAT YOU CAN DO (among other things):
* Plant native milkweed. (You’ll be able to choose from three native species at our plant sale during our World Migratory Bird Day celebration.)
* Plant flowers for butterflies to nectar on. (At our plant sale, we’ll also be selling native nectar plants that adult Monarchs rely on.)
* Join the growing number of people who collect Monarch eggs from vulnerable locations (like the paths of mowers) and raise them indoors for release (instructions on-line).
* Refrain from celebrating a birth or death by releasing commercially raised butterflies.
* Be ultra-cautious in your use of pesticides.
* And be a citizen scientist—that is, add your observations of eggs and adults to the data at Monarch Watch (http://www.monarchwatch.org/) and/or the Monarch Larva Monitoring Project (http://www.mlmp.org/).
Such a fragile balance. "The Monarch butterfly unites the three countries of North America in peace. It is an ambassador of peace which requires protected areas and ecosystems that are preserved through sustainable agricultural and forestry practices. Let us continue to work together to maintain a healthy and balanced ecosystem for all North America."—President Jimmy Carter
FOR MORE INFORMATION:
Tundra Swans by Joel Trick
By Kate Redmond
This year marks the 100th anniversary of the Migratory Bird Treaty Act of 1918, a landmark piece of legislation aimed at protecting birds.
To set the stage, at the beginning of the 20th century, bag limits on waterfowl and other game birds were generous (if they existed at all), sometimes allowing hunters to take as many as 75 ducks daily for 150 days. Birds were killed, an estimated five million annually in the late 1890’s, for their feathers, used in women’s hats and other fashion items (https://www.npr.org/sections/npr-history dept/2015/07/15/422860307/hats-off-to-women-who-saved-the-birds).
In some areas, it was a tradition to see how many birds you could shoot on Christmas Day. (This “Christmas Side Hunt” inspired Frank Chapman to launch an alternate tradition: the Christmas Bird Count, in 1900.) Wood Ducks had disappeared from much of their historic range. The Passenger Pigeon, which darkened the skies in uncountable numbers into the mid-1800s, was gone, the victim of habitat destruction and massive overhunting. (Pigeons were shot even while sitting on eggs, and the plump fledglings were killed before they could leave the nest.) The last Passenger Pigeon had died in the Cincinnati Zoo in 1914.
The Migratory Bird Treaty Act of 1918 (MBTA) united the United States and the United Kingdom (on behalf of Canada) in an effort to protect migratory birds, dead or alive, by making it illegal to “pursue, hunt, take, capture, kill, possess, sell, purchase, barter, import, export, or transport any migratory bird, or any part, nest, or egg or any such bird, unless authorized under a permit issued by the Secretary of the Interior;” and the Act also established the government’s role in codifying hunting regulations. It had its roots in the Weeks-McLean Migratory Bird Act of 1913, which attempted to protect songbirds and other migratory birds because of their value as controllers of insect pests. The MBTA passed with bi-partisan support, which it has enjoyed ever since. Like Passenger Pigeons, the number of birds that have benefited from the MBTA in the last century is uncountable.
There have been revisions of the MBTA since 1918. Mexico, Japan, and Russia have signed on; the law was broadened to provide protection for habitat; bird species, including some that don’t actually migrate, were added (and some, like the non-native Mute Swan, were removed); eagle feathers may be possessed by Native American tribes for religious ceremonies, and feathers may be used in Alaskan native artwork; and, controversially, an exemption was made for inadvertent killing of birds during military training and testing exercises. http://www.audubon.org/news/the-history-and-evolution-migratory-bird-treaty-act. Permits are issued for activities like hunting, falconry, taxidermy, education, research, and killing/removal of nuisance birds.
Technically, the law makes it illegal to possess last year’s nests (though songbirds do not re-use them) and even feathers, potentially putting nature centers, Scouts, science teachers, and nature-lovers afoul of the law. Knocking down an occupied robin or swallow nest above your back door is also illegal, and MBTA protection even extends to 19th-century bird dioramas and to old nest and egg collections.
Not everyone is in love with the MBTA. Birds face threats today that didn’t exist 100 years ago—wind farms, power lines, communications towers, oil spills, industrial wastewater ponds, etc. The MBTA allowed wildlife agencies to charge individuals who willfully took birds illegally, and it also provided an incentive for companies and utilities whose operations result in accidental kills (called “incidental takes”) to adopt “best practices.” The historic intent (and proven track record) of the MBTA has been threatened since 2015, when the US Fish and Wildlife Service, the agency that enforces it, announced their plan to reconsider prosecution of “incidental takes” caused by industry practices. In 2017, utilities and other businesses were exempted from accountability and enforcement under the MBTA for killing non-game, migratory birds. As the National Audubon Society points out, this removes any incentives for companies to protect birds.
As of mid-April, 2018, the Interior Department announced that corporations or individuals whose actions result in the accidental killing of birds will not be prosecuted. In an article in the Washington Post, reporter Darryl Fears quotes from the new Interior Department guidelines: “the take [killing] of birds resulting from an activity is not prohibited by the Migratory Bird Treaty Act when the underlying purpose of that activity is not to take birds. ‘For example,’ the guidance said, ‘a person who destroys a structure such as a barn knowing that it is full of baby owls in nests is not liable for killing them.’ All that is relevant is that the landowner undertook an action that did not have the killing of barn owls as its purpose.”
Here’s the full list of protected species: https://www.fws.gov/birds/management/managed-species/migratory-bird-treaty-act-protected-species.php (the first half of the list is “alphabetical,” but if you scroll down about half way, the same birds appear listed taxonomically – ducks, loons, grebes, etc.
For more information, see:
By Kate Redmond
Shakespeare asked, “What’s in a name?” Because of their size and the fact that they will prey on small birds, older field guides call American Kestrels (Falco sparverius) Sparrow hawks, which is what its species name, “sparverius,” means. Like the Eurasian Kestrel, a rare visitor to North America, the American Kestrel is a falcon, but the Eurasian Sparrow hawk is in a different raptor family, the Accipiters.
American Kestrels have a huge range -- they are permanent residents across much of the United States, northern Mexico, and a pretty big chunk of South America (here’s their eBird footprint http://ebird.org/ebird/map/amekes), and they breed, but don’t overwinter, across the northern Great Plains and Rockies and in Canada well into the Arctic Circle. These remarkably adaptable birds are found in scrublands, grasslands, and agricultural areas and on woody edges from sea level to elevations of 14,000 feet, wherever there is hunting and nesting habitat. They are a common sight perched on telephone wires during Wisconsin winters -- often with a small rodent dangling from their talons.
Kestrels, our smallest falcons, are about nine to eleven inches long with wingspans close to two feet -- they’re roughly the size of Mourning Doves and are often mistaken for them. Kestrels are sexually dimorphic (“two forms”); males are more colorful than females, and females are about 10% larger than males. https://www.birdwatchingdaily.com/blog/2015/04/17/armchair-birding-compare-male-and-female-american-kestrels/. Both have a rust-colored back and a pair of dark markings called moustache marks on each side of their face. Two black spots on the back of the neck are thought to mimic eyes and may startle predators attacking from the rear. They are often heard before they’re seen; their most common call is series of loud klee-klee-klee or killy-killy-killy notes https://www.allaboutbirds.org/guide/American_Kestrel/sounds.
Their flight is swift, and their silhouette is described as “anchor-like.” Because they have less muscle mass, they are not as “bulky” as the larger Merlin and Peregrine falcons and so can survive with proportionately less food. They may grab insects out of the air, but they typically hunt from perches or while hovering, ambushing their prey rather than chasing it.
A kestrel’s diet changes with the seasons. Insects, especially dragonflies and large grasshoppers, provide the bulk of their food in warmer months, and they also catch beetles, caterpillars, earthworms, crayfish, frogs, bats, mice, and songbirds (and they’ve been seen taking birds as large as a flicker). Rodents, chiefly voles (Microtus), make up the bulk of their winter diet in Wisconsin. Kestrels generally eat smaller prey on the ground and carry their larger prey to a perch, and they will cache surplus food for later use, especially in winter. They sometimes hunt in family groups. They are preyed on by larger raptors like Red-tailed, Cooper’s and Sharp-shinned Hawks, and by crows, raccoons, skunks, and rat snakes.
Voles mark their comings and goings with scented urine, and researchers have found that these trails reflect ultraviolet light. Many references say that kestrels can spot these trails from above, allowing them to determine whether an area will be a productive hunting ground. Other researchers say that although gulls, shorebirds, Passerines (the perching/songbirds), and a few other groups of birds do have UV vision, raptors are not very sensitive to UV light and do not use it to find prey.
Unusual among hawks and falcons, kestrels are cavity nesters that use old woodpecker holes, natural hollows in trees, and even crevices in rock piles, as well as man-made nest boxes, and they will kick out any bird or squirrel that may already be in residence. They can be fairly tolerant of human neighbors -- I once saw a kestrel fly into a hole under the eaves of a building in the middle of a small town. Trees at the edge of a woodland are ideal sites.
Males defend territories during the nesting season and will chase raptors much larger than they are. He courts with aerial displays, flying into the sky and then plunging in a steep dive while vocalizing. The female responds by flying with slow, stiff, dove-like wingbeats, and the pair may exchange gifts of food, on the wing.
The male searches for potential nest sites and then takes the female around and shows them to her, but she makes the final choice. Inside the cavity, the nest is primitive -- often just a scrape on the floor. Both parents incubate the eggs, though the female pulls the lion’s share of the duty. The young fledge after about a month, but the parents continue to feed them for a few more weeks, and after that, young birds may congregate with young from other nests.
Southern populations don’t necessarily migrate, but northern-breeding kestrels do, leap-frogging over resident populations to overwinter in the southern United States and in Central America. They are solitary in winter -- females head south first and claim territories in open areas on their wintering grounds, leaving the later-arriving males with the less-choice habitats. Males fly north first.
Kestrels have, as the TV stations like to say, “A Wisconsin Connection.” Wisconsin biologist Fran Hammerstrom, who studied Greater Prairie-Chickens for decades, decided to try to encourage kestrel nesting on the Buena Vista Grasslands by erecting 40 nest boxes in 1968. That project morphed into the Central Wisconsin Kestrel Research project, which she headed for the next 30 years, until her death. The project continues today.
It’s hard to imagine that populations of a bird that is so abundant and adaptable and that enjoys such a broad menu might be shrinking, but kestrel numbers on the East and West coasts are in decline. Data from the North American Breeding Bird Survey show an over-all drop in numbers of almost 50% from 1966 to 2010. The main challenge is the loss of nesting and hunting habitat due to urbanization, reforestation, and “clean” agricultural practices that remove dead trees and hedgerows. The use of pesticides that kill the rodents and insects that they depend on, deliberate killing, predation by Cooper’s Hawks, competition with starlings for nest boxes, and collisions with cars and with wind and communication towers also take their toll.
The National Audubon Society considers kestrels “climate threatened” http://www.audubon.org/field-guide/bird/american-kestrel, but others suggest that the falcons may benefit from climate change because it could make prey more available, cause the birds to nest earlier, giving them first crack at good nest sites and territories, and allow the young of the year to get more experience and conditioning before they migrate. What can you do for kestrels?
LINKS BBS and CBC maps https://www.mbr-pwrc.usgs.gov/infocenter/i3600id.html
http://www.audubon.org/field-guide/bird/american-kestrel To find out more and get involved with Central Wisconsin Kestrel Research, please visit the program’s website at: http://www.kestrelresearch.com
By Kate Redmond
Seven things I didn’t know about Short-eared Owls (Asio flammeus):
Because Short-eared Owls are found in a variety of open-country habitats with short vegetation like grasslands, tundra, dunes, marshes, hayfields, and shrubby fields, they’ve earned regional names like Prairie, Marsh, and Bog Owl. They breed in scattered locations in central and northern Wisconsin but are more commonly seen here in winter. If you’re looking for a place to take a winter walk, try the trails at Forest Beach Migratory Preserve, the northwestern part of Harrington Beach Sate Park, and the Schwengel Waterfowl Production area on Six Mile Road, northwest of Belgium. You might find some Short-eared Owls on the prairies.
With a short neck and tail, Short-eared Owls appear to be all wing. In the summer, they might be mistaken for a Northern Harrier (a.k.a. Marsh Hawk), which lives in the same grasslands and hunts for the same food in a similar fashion (and sometimes steals prey from the owls). Short-eared Owls are brown and streaky; the undersides of their wings are light-colored, and they lack the harrier’s white rump patch. They are between crow-sized and Great Horned Owl-sized, but their bulk is all feathers. They weigh in at a pound or less. (Females are a larger and heavier than males.) Like other owls, Short-eared Owls have a keen sensory repertoire. Raptors’ eyes are located on the front of their head, allowing binocular vision, and their eyesight is sharp.
Like the “horns” of a Great Horned Owl, their “ears” are actually feather tufts; the real ear openings are covered by skin and feathers, and as in many species, ear placement is asymmetrical, which allows owls to triangulate the location of their prey. Audio information is collected via the facial disk, a concave array of feathers around the bird’s eyes. Moving the facial feathers adjusts the amount of sound that is fed to each ear. They have a number of vocalizations (the young even call from within the egg), but their displays are visual, as befits a bird of open spaces.
In springtime, when the breeding season gets under way, and especially in winter, they may be communal, and groups of a dozen or more are common in winter.
During the summer, they hunt day or night, but on their wintering grounds, they are crepuscular – active at dawn and late afternoon/dusk. Voles are their main prey, and they also take mice, shrews, rats, rabbits, and muskrats. In summer, they’ll eat some insects and an occasional bat, and they’ll also hunt for grassland birds and for young gulls and shorebirds along the coast. They mostly hunt from the air, quartering back and forth over a field, sometimes hovering, carried in a stiff, bouncy, mothlike flight by their long, rounded wings. After a successful hunt, they carry their prey with their talons – unusual among owls.
Females make a rudimentary nest on the ground by flattening the grass and maybe laying down a few sticks, and they lay an average of five to seven eggs. The male feeds her while she incubates (their pair bond lasts for one season) and brings food for her to give to the young after the eggs hatch. If her nest is approached, she will try to intimidate or distract the intruder. Since they nest and often perch on open ground, they are vulnerable to attack by foxes, coyotes, dogs, and raccoons, as well as by other raptors.
Short-eared Owls are migratory. Birds from the north move into Wisconsin in winter as most of our breeding Short-ears fly farther south. Their populations reflect the highs and lows of their rodent prey, and they are also nomadic, abandoning areas where prey numbers are low. It’s tough to get an accurate fix on their status.
While they are not federally endangered, their numbers are declining in the southern part of their range in North America, and they are considered endangered, threatened, or species of special concern in most of the upper midwestern and Great Lakes states. In Wisconsin, they are a Species of Greatest Conservation Need (species that have “low or declining populations and are in need of conservation action”). Habitat loss and fragmentation and changing agricultural practices (including increased acreage dedicated to the production of corn for ethanol) are big factors, as they are for other grassland bird species. Their low flight puts them into the path of cars, and they have an affinity for airport runways.
nice pictures - https://wsobirds.org/apg-seow