Thursday, March 31, 2016

American Redstart

These images are last year’s photos of male American Redstarts. Male redstarts do not become orange and black until they are at least two years old. Younger males look like females, but usually show black patches on their head, breast or back. These black areas increase as worn feathers are replaced as the bird ages (Sherry and Holmes 1997).


Tuesday, March 29, 2016

Bank Swallow

I continue to try to catch up with some of last year’s photos. I do not remember when or where I found this Bank Swallow.

Bank Swallows range around the northern hemispheres of world. In North America, they often breed in river banks and cliff sides. I have often found them nesting in construction sand mounds. Sand and gravel quarries often provide nesting areas. The problem with these latter sites is that they tend to be transitory. Dirt piles left by builders, for example, often remain, at best, for a few years. The result is that Bank Swallows do not show much “nest-site fidelity.” Long-term ties to specific colony sites are not to the swallow’s advantage (Garrison 1990).

Sunday, March 27, 2016

Indigo Bunting

I took this Indigo Bunting photograph last spring in Northfield. Because first-year males can look like females, the gender of this bunting is unknown. First-year birds learn their song from neighboring buntings, but they do not sing their father’s song. The result is local song dialects, which can last up to 20 years. The dialects are not permanent, and can change, especially if new individuals move into an area (Payne 2006).

Friday, March 25, 2016

Baltimore Oriole

Male Baltimore Orioles don’t molt into their bright plumage until their second  breeding year.  Males in their first year look like females, but can attract mates and successfully breed (Rising and Flood 1998).

Last summer, this Baltimore Oriole fed at a jelly-filled feeder at our Dundas banding station.  Mark Catesby described the Baltimore Oriole in 1731, naming the bird for the founders (whose colors were black and orange) of the Maryland colony. In 1758, Linnaeus named it the Small Yellowish Jackdaw, thinking orioles are closely related to crows. Later the name was changed to Oriole, on the assumption that the birds were similar to Old World orioles. Today ornithologists classify our orioles as blackbirds.

Wednesday, March 23, 2016

Brown Thrasher

This photo was taken on 27 May 2015 in Dakota County, Minnesota. Brown Thrashers are found in eastern North America. Thrashers and mockingbirds belong to the family Mimidae, which recent DNA work demonstrates to be closely related to starlings.

Brown Thrashers have the largest song repertoires of all North American songbirds. Over 1100 song types are identified by ornithologists (Cavitt and Haas 2014). Ornithologists recognize two races of Brown Thrasher, the eastern Toxostoma rufum rufum and, in the western Great Plains, T. r. longicauda. Most Minnesota birds should be the eastern race, which can be identified by white, not buffy, wing bars.

Monday, March 21, 2016

Eastern Meadowlark

Elsewhere in this blog, I have written about the difficulties in identifying Eastern and Western meadowlarks, both by plumage and by song. It does not help that both species occasionally learn each other’s song. The two species also hybridize, although the offspring of these birds are often sterile (Jaster et al. 2012). 
Nevertheless, this individual, singing last spring near Circle Lake in Rice County, went down i my field notes as an Eastern Meadowlark. According to my first Peterson guide (available for a penny from Amazon.com),  the Eastern sings "two clear slurred whistles, musical and pulled out: tee-yahtee-yair (last note 'skewy' and descending)."  The Western, on the other hand, sings "a variable song of seven to ten notes, flute-like, gurgling, and double-noted; very unlike clear slurred whistles of Eastern Meadowlark.”  A South Dakota friend translates this call to "Have you planted your wheat yet?"

Saturday, March 19, 2016

Yellow-bellied Sapsucker

Last spring I found this Yellow-bellied Sapsucker gleaning insects in the treetops at the Cannon River Wilderness Area near Northfield. Sapsuckers are famous for drilling sap wells, and often damage trees in the process. In the spring, the wells harvest upward moving sap in tree xylem. Later wells capture downward-flowing phloem sap. Insects trapped in the sap wells are also consumed.

Sapsuckers also glean and probe for insects from tree bark and leaves. They sometimes capture insects in the air, in the manner of flycatchers. They also dine on tree buds. But most of their time is spent drilling and maintaining their wells. This dependence on live trees obliges sapsuckers to be our most migratory woodpecker.

Thursday, March 17, 2016

Turkey in a Crabapple Tree

Turkeys are known to be “catholic” in their diet (McRoberts et al. 2014). These birds will eat almost anything—mostly vegetable matter, but also small animals. The turkeys that Erika and I found at the University of Minnesota Landscape Arboretum on 5 March 2016, gorged on crabapples.  The aforementioned authors list a variety of tree fruits that turkeys enjoy, but they do not mention crabapples. Oaks are a staple of their diet.

The turkeys we watched flew up into the trees to feed. This behavior is not unexpected. Turkeys usually spend the night in trees. Our turkeys looked ungainly in the delicate apple branches, but the birds proved to be adept acrobats.

Tuesday, March 15, 2016

Wild Turkey Track

On 5 March 2016, Erika and I discovered a turkey track at the University of Minnesota Landscape Arboretum. In short order, we found a flock of 15 birds.
Turkey behavior is complex and variable. Both males and females may form separate flocks, which can be composed of up to 40 individuals. Some winter turkey flocks exceed 200. 
Males form leks, strut about, and try to attract the attention of females. Dominant males mate with multiple females. The females then leave their female flock and raise their young. Young males remain with their mother until they exceed her in size. Males then join independent male flocks. (McRoberts et al. 2014).

Sunday, March 13, 2016

Greater vs. Lesser Scaup

Greater and Lesser scaup are closely related ducks that are hard to tell apart.  Greater Scaup, like in the first photo, have large, black, bill nails and rounded heads. The head may be slightly highest in the front, but head shape often depends on what the duck is doing (diving, resting, etc.). The head often shows a green sheen, but this field mark depends so much on light conditions that color is not a dependable trait. The back is finely barred, making it appear brighter white than in the Lesser Scaup. Finally, the sides of the Greater Scaup often appear to be brighter white.

Compare the Greater Scaup to the duck in the second photo. The bill nail is much less prominant, barely visible from the side. The head is slightly crested behind the head. The black back barring is more pronounced, and the sides are not as bright white. The head sheen appears to be purple, not green.
So what is this last scaup? The bill nail is not pronounced and the head is clearly purplish. On the other hand, the head is not crested and appears to be highest in front. The back and side seem to be very pale. I have an opinion about this bird’s identity, but I welcome reader input. Perhaps the correct guess may be “unknown species of scaup.”
I took the first and the last photos at the Minnesota Valley National Wildlife Refuge’s Bass Ponds last Friday, 11 March 2016. I do not recall where I took the Lesser Scaup photo. All these ducks are drakes. Identification of the hens requires even more finesse.

Saturday, March 12, 2016

Yellow House Finch

On 8 March 2016, Erika and I walked in the neighborhood. We heard the clear, complex notes of an House Finch from a nearby treetop. Despite its being a common bird, I looked up at the singer. To my surprise, this male was bright yellow.

I assumed that these yellow variants are the result of their having high levels of beta-carotene or with low levels of echinenone (either because of what they are eating or because they are unable to metabolize these hormones). See my 2012 post on a yellow House Finch in California.

The situation may be more complicated. LaBarbera (in Toughlittlebirds.com) has an interesting blog post. She writes that red males often hold the richest territories. Younger females are attracted to these wealthy birds. Red males, however, do not raise their young as fastidiously as do yellow males.

Yellow males breed later and and take better care of their young. Older females prefer to mate with these more stalwart males. I have simplified LaBarbera’s report, which includes further variables in this hypothesis. For example, it may be advantageous for a younger male to be red and then become yellow in subsequent breeding seasons. You will find LaBarbera’s post to be fascinating.

Thursday, March 10, 2016

Black-capped Chickadee


Last Saturday, on 5 March 2016, Erika and I encountered a Back-capped Chickadee giving a “gargling” call, with which we were unfamiliar. Gargles are poorly understood calls. They can be complex and variable, containing up to 23 syllable types. Gargles are components of aggressive displays and are often given in winter (Foote et al. 2010).

We are not sure if this chickadee was being aggressive towards us or to other chickadees. Perhaps the bird was defending sap dripping from a nearby branch. The chickadee made repeated visits to the branch, where it drank the sap. Curiously, the above-cited authors do not mention that chickadees drink sap. The behavior is well-known. Bazilchuk (in nasw.org) mentions that chickadees feed on sap icicles. Undoubtedly sweet sap contributes to the high energy needed to survive our cold and often barren winters.

Tuesday, March 8, 2016

Horned Lark

This Horned Lark fed along the snowy roadside during Erika and my drive home last Friday. The bird appeared to be eating weed seeds.

Horned Larks are found around the world, from the Arctic sousth to central Asia and Mexico. They also inhabit Columbia and Morocco (Beason 1995). In Europe, they are known as Shorelarks. Horned Larks are common in prairies, deserts, and agricultural areas. With deforestation, Horned Lark populations increased in eastern North America. During the past 50 years, however, much abandoned land in the east has reverted to forest. As a result, eastern Horned Lark numbers have declined.

Sunday, March 6, 2016

Gulls and eBird

On Friday, 4 March 2016, Erika and I enjoyed a lunch date at the San Pedro Cafe along the St. Croix River in Hudson, Wisconsin. As we ate, a heavy snow began to fall. After lunch, we scanned for birds at the Hudson Lakefront Park. Several gulls flew over the river.

Gulls are confusing. One of the advantages of using eBird is that this listing app asks you for confirming details when you try to report a rare bird. I thought I saw a Ring-billed Gull.  “Rare,” proclaimed eBird.  “OK,” I replied, “How about Herring Gull?” “Rare,” snarled eBird.

Rather than capitulating to eBird and not reporting these gulls, I pulled out my camera and took photos. That first bird proved to be a Herring Gull.  Note the red spot on the bill and the pink legs. A few minutes later, a second gull flew overhead. This one was a Ring-billed Gull! Note the yellow bill with the broad black band. This gulls back is pale compared with the Herring, and its inner primaries are even paler than the back.

Although they let you know when records are questioned, eBird is not very good at letting observers know when rare observations are accepted. I await their verdict.

Friday, March 4, 2016

Pileated Woodpecker


One of the delights of Minnesota birding is the relative abundance of Pileated Woodpeckers. Yesterday, I took this photo out our back window. I am excited every time I see one of these woodpeckers, and I have recently posted on the species.

In many areas Pileated Woodpecker populations are increasing. Forest management favoring older growth forests and retaining large-diameter trees—both alive and dead—contribute to this woodpecker’s survival. In some eastern areas, however, Pileated Woodpeckers are declining due to general habitat destruction (Bull and Jackson 2011).

Wednesday, March 2, 2016

Blue-gray Gnatcatcher

On 19 May 2015, Erika and I watched two Blue-gray Gnatcatchers forage at the edge of the forest in the Carleton College arboretum. Gnatcatchers are active little birds, often hard to see in the dense foliage in which they feed. You often hear their high-pitched, nasal songs. They will often come close and investigate if you make squeaking or spishing noises.

Gnatcatchers are monogamous.  Males contribute to most aspects of breeding. They help build their intricate nests, incubate eggs, and feed young. In the past 25 years, Blue-gray Gnatcatchers have increased in numbers and expanded their range northward (Kersner and Ellison 2012).