Wisconsin birders are looking forward to an excellent finch winter! 

Birds that usually winter in Canada are moving south. These atypical “irruptive migrations” are usually caused by changes in winter food availability and can occur in several northern species especially finches, owls and evening grosbeaks. This year finch species that normally winter in Canada and the northern United States are ranging farther south due to a massive crop failure of fruit and cone bearing trees in Canada.  Birding expert and Ontario resident Ron Pittaway compiles local seed crop and late summer bird observations to create a detailed “Winter Finch Forecast”  available through Ebird every autumn. The Wisconsin Ebird group uses the Pittaway data to create detailed forecasts for our area. Based on the two forecasts we should expect to see Red and White-winged Crossbills, Redpolls, Pine Grosbeaks, Pine Siskins, and Evening Grosbeaks joining resident Goldfinches, House and Purple Finches this winter in northeastern Wisconsin.

Pine Grosbeaks are large finches with heavy black bills and gray sides and red washed black back and reddish pink rump.

Pine Grosbeaks have been steadily moving into the state in small flocks. Look for them on the UW—Green Bay campus feeding on crab apples, especially near the Kress Center. This is a taiga species which is considered an irruptive winter visitor across the Midwest and east.  The last really large widespread movement into Wisconsin was in 1977 and again in 1985. They love to dine on crabapples, high bush cranberries, left over apples in orchards, sumac, mountain ash, and when food supplies are exhausted, the seeds of the box elder ash. Pine Grosbeaks will also switch to backyard feeders when black sunflower seeds are offered, but for now, it is find the fruit trees first!!

Evening Grosbeaks are striking birds, identifiable by their large pale bills and black, white, and bright yellow coloration.

Evening Grosbeaks have been on the decline in Wisconsin in recent years and are usually only seen reliably in the far north of the state. Evening Grosbeaks nest as close as Lakewood, Oconto County, annually. However, based on arrival data, the birds being seen now are coming from the northwest. Observations were reported from Duluth as birds rounded Lake Superior. So far this year there are a few reports in Oconto, southern Brown, and Manitowoc counties.  Their preferred seeds are box elder and other maple species. They will also visit platform feeders supplied with black oil sunflower seeds.

Red and White-winged Crossbill species have staged a massive irruption into Wisconsin. Although these birds are unlikely to come to backyard feeders, look for them in conifer swamps and bogs in the far North, the Green Bay area, and in conifer groves along the Lake Michigan Lake shore from Manitowoc down to Chicago. Interestingly, according to Ebird, the Red crossbills arriving in Wisconsin are from western Canada escaping a hemlock seed crop failure in the Pacific Northwest.

Common Redpolls, Pine Siskins, and Goldfinches are common winter residents throughout northeastern Wisconsin and while abundant are not occurring in higher than expected numbers. Purple Finches have apparently moved on and are now below expected numbers. House Finch populations are way up after declining for a number of years. These birds prefer small seeds including birch, alder, willow, tamarack, and weedy field forbs. They will visit backyard nyjer (thistle) and black oil sunflower seed offered in feeders.

Two non-finch species are also irrupting south in response to the seed failures in Canada.

Bohemian Waxwings, while not finches, are another fruit loving bird that is irrupting southward because of the Canadian fruit crop failure and are expected to appear in large numbers in our area this year. In fact a flock of over 250 Bohemian Waxwings seen in Door County was recently reported to Ebird. These birds are voracious fruit feeders so look for them in urban or natural areas with fruit bearing trees like mountain ash, Juniper, and crabapples. These assertive birds will compete with Pine Grosbeaks for access to fruit trees. Bohemian waxwings form pure flocks of their own species or in mixed flocks with Cedar Waxwings.

Bohemian Waxwings are very similar to Cedar Waxwings. Bohemians are larger and have black, yellow, and white wing bars.

Rose-breasted Nuthatches feed on conifer seeds and so are also arriving in high numbers from the same northern regions because of the cone failure. They are often seen at platform feeders eating sunflower seeds and also will feed at suet feeders.

Feeding Finches:

Ebird recommends that people hoping to attract winter finches to their yards put out platform or other large flat surface feeders with black oil sunflower seeds. All finches like small seeded sunflower seeds and some finches like Goldfinches, Redpolls and Siskins also will feed on nyjer in tube or bag feeders. Most finches are attracted to water, so maintaining a heated bird bath or water feature will bring birds to your yard.

It is going to be a very delightful finch winter. 

More Information:

•  Tom Erdman contributed to the text and Tom Prestby provided photos

• Wisconsin Ebird’s detailed “Winter Finch Update” provides an update on the status of Wisconsin’s winter finch flight so far, maps of sightings, and tips on finding these species in your neck of the woods: http://ebird.org/content/wi/news/wisconsin2019s-winter-finch-update-1-1
• Birding expert Ron Pittaway has been publishing a Winter Finch Forecast for several years. Access  his yearly forecast on ebird: http://ebird.org/content/ebird/news/ff2012
• Read  more about the irruption of red breasted nuthatches in“The Pathless Wood”, a blog by Ottowa naturalist Gillian Mastromatteo: http://meadowhawk.wordpress.com/tag/ron-pittaway/
• Ebird is a real-time, online checklist program run by the Cornell Lab of Ornithology and the National Audubon Society. The website provides access to basic information on bird abundance and distributions. http://ebird.org/content/ebird/
• UW—Green Bay graduate student and Biodiversity Center technician Tom Prestby took the photos for this blog entry. See his other fabulous bird photos at http://www.pbase.com/tprestby

2012 is the worst year on record for West Nile Virus (WNV) in the United States since the disease first appeared in New York in 1999. Forty-seven states, including all states in the Western Great Lakes have reported cases of both infected birds and humans and all 50 states have reported infected birds.

West Nile Virus is transmitted by the bite of a mosquito. While several species of mosquitoes can harbor the disease, the most common species we are likely to encounter in urban and suburban areas is Culex pipiens, the northern house mosquito. Culex and the other suburban mosquitoes prefer to breed in small containers or stagnant water with lots of organic debris like animal droppings or decaying leaves. The disease is transferred when a mosquito bites an infected bird. That mosquito can then pass the virus on by feeding on other birds, or susceptible mammals including humans.

Culex pipiens (Northern House Mosquito), photo by G. Fewless

Unfortunately, the disease can heavily impact bird populations. Crows are particularly sensitive to WNV and populations in North America declined by as much as 45% after the WNV epidemic in 2002. Robin populations were increasing in the 1990s, but have leveled off since the introduction of WNV.

Increased biodiversity provides an advantage against infection. Scientists have shown that areas with more bird species tend to have fewer mosquitoes carrying WNV and fewer cases of human infections (Ezenwa et al., 2006; Swaddle and Carlos, 2008). Researchers believe the effect is related to the susceptibility of different bird species to the virus. Some birds like American robins are known to be good hosts and are better at spreading the disease because mosquitoes seem to like to feed on them and they are better carriers than some other species. According to Tony Goldberg, an epidemiologist at UW—Madison, robins are good hosts and can act as “super-spreaders” of the disease. In areas with lots of robins and few other bird species there are higher total number of human infections. But not all bird species are good hosts for the disease so it is thought that higher bird diversity reduces infection rates because mosquitoes are less likely to encounter a good host and therefore less likely to become infected and transmit the disease. The presence of birds that are poor hosts reduces or “dilutes” transmission rates of the disease between birds and also to humans. Similar results have been shown for other animal vectored  diseases like Lyme and Hantavirus (Keesing et al. 2010).

Controlling mosquitoes

• Large ponds and healthy wetlands contain fish and invertebrate predators like dragonfly larvae that feed on mosquito larvae that naturally keep mosquito populations in check. The problem mosquitoes are those that prefer to breed in stagnant water like puddles, tree-holes, and other small containers.
• Make sure you are not inadvertently providing mosquito breeding containers. Be sure to make sure your gutters are not clogged and that old tires or children’s toys or other containers cannot hold water.
• Empty containers of water such as bird baths, kiddie pools, plant trays, twice each week.
• Consider using mosquito dunks that contain Bt in yard water features that are too large to empty each week. The dunks contain the bacteria Bacillus thuringiensis Israliensis, which produces a toxin that kills mosquito larvae, but is non-toxic to other wildlife.
• Where long sleeves and long pants and use CDC recommended mosquito repellants
• Fans can be effective at deterring mosquitoes in a small area such as on a deck or a patio area. Mosquitoes are weak flyers and fans will keep them at bay. Fans also blow away exhaled carbon dioxide that attracts mosquitoes.

Increasing backyard bird diversity

• There is no reason to stop feeding or watering birds because the disease can only be transmitted by the bite of a mosquito. The disease cannot be transmitted from bird to bird, from birds to people or from people to people.
• Provide a variety of feeders and feeds that attract different species.
• Create as much quality habitat as possible. Include vegetation, shrubs, and trees that provide forage and cover from predators.
• Try to match natural habitats by planting vegetation that includes a diversity of plants and plant types.
• Provide bathing and watering areas, but be sure to keep them mosquito free.
• Keep your feeders and feeding areas clean to prevent the transmission of bird diseases. There are no known cases of West Nile transmission between birds in nature, but stressed, injured, or birds sick with other diseases will be more susceptible to West Nile infection from mosquitoes.

References

Ezenwa, V.O. et al. 2005. Avian diversity and West Nile virus: testing associations between biodiversity and infectious disease risk. Proceedings of the Royal Academy: Biological Sciences 273:109-117.

Kessing et al. 2010. Impacts of biodiversity on the emergence and transmission of infectious diseases.    Nature  468: 647–652

Swaddle JP, Calos SE (2008) Increased Avian Diversity Is Associated with Lower Incidence of Human West Nile Infection: Observation of the Dilution Effect. PLoS ONE 3(6): e2488. doi:10.1371/journal.pone.0002488

Zimmer, C (2012) West Nile Virus: The Stranger that Came to Stay. Discovery Magazine “The Loom” Blog. http://blogs.discovermagazine.com/loom/2012/08/17/west-nile-virus-the-stranger-that-came-to-stay/