116 3rd St SE
Cedar Rapids, Iowa 52401
A red crossbill ‘invasion’
Birding: These birds have been here before, but still rare
In mid-August, the bird-watching world was excited about the irruption of red crossbills into the Upper Midwest.
Eyes and ears turned skyward and treeward for hopes of seeing a flock of these rare finches. Their “kip kip kip” flight call would soon resonate through the Eastern Iowa Corridor.
Avian irruptions (sometimes referred to as “invasions”) occur when part of a population of birds suddenly moves outside of their core or typical range, often in response to low food supplies.
Weeks before this last Iowa irruption, the signs of a large crossbill movement already had been observed in states like Minnesota and Wisconsin. It wouldn’t be long before the reports came pouring in all over the Hawkeye state.
August reports of red crossbill in Iowa is not a novel thing. Although their occurrence in Iowa is considered rare and erratic, historical data shows August is when they can start showing up. They can be seen in any month of the year in Iowa, but more typically in the winter months.
Nesting has been recorded in July. Before this August crossbill deluge was a small hint of irruption. There were two separate reports in central Iowa on July 11.
Most records for red crossbill occur in metropolitan areas and it was no different for this last big wave. On Aug. 14 a report of 13 came from Macbride Nature Recreation Area, followed by a whopping 42 at Glendale Cemetery in Des Moines.
Not only do cities unsurprisingly have the most bird-watchers, they also have the most bird feeders and largest stands of conifer trees.
Other areas in the Eastern Iowa that have recently had red crossbills were along the Sac and Fox Trail and at Wapsipinicon State Park, both in late August. Pinicon Ridge County Park had a lone crossbill in early September. The flock of red crossbills at Wapsipinicon continued into mid-September and may even still be lingering in the impressive stands of white pine.
An interesting thing about red crossbill irruptions is the flocks can be pinpointed to regional populations by sound recordings. It might be logical to think most are coming from Canada, perhaps misplaced by the wildfires. However, recordings, in the form of a spectrogram, demonstrate many of the crossbills are coming from populations out west.
These include the ponderosa pine or type 2 that occur throughout the Rocky Mountains and the douglas-fir or type 4, which mainly occur in the Pacific Northwest. Go to the Finch Research Network for more information about the different red crossbill types, how spectrographic analysis is used to define types, where they come from and where they tend to irrupt.
Red crossbill types are based off a number of categories, including call type, bill morphology, body size and conifer tree preference. In fact, a new species was named in 2017, the Cassia crossbill, which is very closely related to red crossbill. Supposedly confined to one county in Idaho, Cassia crossbills also have been recorded in central Colorado over the past few years with a recording going back over a decade. Why the species is suddenly more recognized in Colorado still is not understood well.
Some good news is, if you missed the memo about this red crossbill irruption, it might not be too late to see them. There still are reports coming in piecemeal. The area around the golf course at Wapsipinicon State Park might still harbor some. These particular crossbills like white pines. If you have any white pines producing a good cone crop this year, keep an eye and an ear out this fall and winter.
BIRDS OF OCTOBER
- Sparrows, sparrows, sparrows! Sparrow numbers and diversity will peak in October. Try “pishing” some sparrows in their habitat. Nobody really knows why birds, especially sparrows, respond to pishing. There is no vowel sound when doing a pish, just “P-shhhhhhh.” Repeat it three or four times quickly.
Did it work? If you come across a bush or hedgerow with sparrows, first position yourself where you can get a good look. If doing photography set yourself in a position with some good lighting. Then try to pish. Often, sparrow will pop up and sit on a bare branch just long enough to get a good look or photo.
- About 17 species of sparrows migrate through Eastern Iowa in October. Grasshopper, lark and Henslow’s sparrows have basically headed south by the start of the month. Dark-eyed junco, American Tree and fox sparrows will first arrive in late September or early October, with numbers ramping up as the month progresses. Sparrow species found in low numbers include clay-colored, vesper, LeConte’s and Nelson’s. Look for LeConte’s on the perimeter of marshy areas or in damp prairie. Look for Nelson’s in marshy areas, but they also can show up in the same habitat as LeConte’s. Swamp sparrows will usually be the most abundant sparrow species while looking for Nelson’s.
- Some of the best places to look for fall sparrows are at Hawkeye WMA in Johnson County. Hedgerows, brushy spots, wet prairies and large wood piles can be some of the best habitat types to find large congregations of sparrows. Some productive roads to cruise include hedgerows along James Avenue NW north of its intersection with Swan Lake Rd NW, grassy to brushy ditches along Swan Lake Rd NW west of its intersection with Half Moon Ave NW, marshy areas along Greencastle Ave NW north of its intersection with Swan Lake Rd NW and wet prairie areas along Swan Lake Rd NW where the road runs north/south and just to the southeast of Matson Pond.
- Chain-O-Lakes WMA in Linn County and Cedar River Crossing in Johnson County also are excellent places to look for sparrows in October.
Birding calendar
- Oct. 8, 10 a.m. to 2 p.m. in Iowa City — “Get Out,” an outdoor recreation festival at City Park. This family-friendly event is sponsored by Iowa City Parks and Recreation and will feature a range of activities from canoeing, bird walks and archery to LARPing, plein-air painting and yoga. Attendees also will be able to grab food from local food trucks and other prepared food vendors. ICBC will provide guided bird walks at 10:15 a.m., 11:15 a.m. and 1 p.m. and host a table with information and a bird activity for kids. No admission fee or registration required. Drop in anytime from 10 a.m. to 2 p.m.
- Oct. 22, 7:30 a.m. — River Valley Wetland walk and (at 10:30 a.m.) Althea Sherman Swift Tower Tour. We’ll visit River Valley Wetland in Cedar County for a guided bird walk with Mark Brown. Target birds are late fall migrants such as orange-crowned warbler, hermit thrush, fox sparrow, purple finch and rusty blackbird. Then we’ll head to Bickett-Rate Preserve for a guided tour of Althea Sherman’s Chimney Swift Tower with Barbara and Mike Boyle. Return time is around 12:30 p.m. Options for meet-up: Bird walk meet at the North Dodge Hy-Vee parking lot near the gas pumps (1125 N Dodge St., Iowa City) at 7:30 a.m. to carpool. For swift tower tour only, meet at 10:30 at Bickett-Rate Preserve (600 225th St., Tipton).
Brandon Caswell has a keen interest in natural and social sciences. He enjoys bird-watching and nature photography in his spare time. He and his wife live in Marion with their two children.
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