Ladder-backed and Nuttall's Woodpeckers

Also at the Bentson State Park bird feeders was the Ladder-backed Woodpecker (above), a common bird of the southwest. This "zebra-backed" woodpecker is quite similar to the Nuttall's Woodpecker (below) found in the oak woodlands California.  Fortunately for birders trying to identify them, the two species' ranges barely overlap. (In the limited area of overlap, the two species have been known to hybridize.)

In my photos, the Ladder-backed Woodpecker is a male and the Nuttall's is a female--hence the red on the Ladder-back's head, which is not present on the female Nuttall's. Only one of the field marks mentioned by Sibley to separate these woodpeckers is evident in my photographs. Note the upper back on these birds. On the Ladder-backed Woodpecker, the upper back is whitish with thin black stripes. In the Nuttall's Woodpecker, in a photograph from the California coast, the upper back is solid black. Sibley's suggestion that the feathers behind the bill (the lores) are white in the Ladder-backed and buffy on the Nuttall's are not born out by my photos.

Despite both species' being common within their respective ranges, neither woodpecker has been well-studied by ornithologists. With few exceptions, observations on the breeding biology of both birds tend to be "incidental and superficial" (Lowther 2000, 2001).

Golden-fronted Woodpecker

Bentson State Park is another location birders visit in Texas' Lower Rio Grand Valley. For us the disadvantage of this park was their admission fee; our senior Federal passes did not allow us free access to state parks. We visited Bentson twice and listed a few different birds. One is the Golden-fronted Woodpecker, a tropical American species that ranges north through Texas to Oklahoma.

Not only does this woodpecker look similar to Red-bellied Woodpecker, the two species hybridize. Golden-fronted Woodpeckers have expanded northward. Apparently hybridization occurs where contact between the two species is recent (Husak and Maxwell 1998). Surprisingly, neither the interbreeding, nor this woodpeckers' biology in general, has been well-studied by ornithologists.

Spring Migration

As stalwart readers of this blog are aware, I have been taking a series of bird portraits with the subjects facing the camera. While perhaps not the best photographs for identification purposes, they do present novel views of plumage patterns. A good example is on this Ovenbird, with the malar stripes continuing past the bill and bordering the orange crown; or this Yellow-rumped Warbler, glaring at me earlier this spring.

Banding has been extremely slow this spring. Although I observed several mixed flocks of migrating warblers, none were near my nets. I find myself already looking forward to the fall migration. In any event, both these photos were taken in Northfield, Minnesota, during May 2012.

Black-necked Stilt

Black-necked Stilts, although looking a bit like circus clowns on bright pink stilts, are nonetheless graceful shorebirds found in southern and western North America. They are vagrants to Minnesota and the Dakotas. We found them nesting near Aberdeen, South Dakota, but I am unaware of Minnesota breeding records.

Stilts eat brine flies. Stilts are often found in shallow and temporary ponds with emergent vegetation. The problem is that this habitat often collects agricultural contaminants. These birds are particularly susceptible to selenium, which causes embryo deformities (Robinson et al. 1999).

In March, Erika and I found small flocks of Back-necked Stilts at the Santa Ana National Wildlife Refuge. To my amazement, my dragonfly expert Scott King looked at this photo and asked about the damselfly. "Is the damselfly in the tip of the bird's beak, or is it on the branch behind?" I never saw it, not in the field or in the photograph. Look closely! The odonate is on the branch behind the beak. This episode demonstrates that proficiency in finding and identifying dragonflies (and birds) takes years of practice.

Odonate Additions

On Friday at the University of Minnesota Landscape Arboretum, Erika and I found two unfamiliar dragonflies. Oddly, I already had photographs of both, except that previous photos were all of females. This season's odonates are males. The top critter is a Horned Clubtail, a species I first found in the Carleton Arboretum and blogged about on 20 September 2011. I needed assistance identifying the clubtail because this species' tail is not clubbed, but rather has widely branched cerci, the spines at the end of the abdomen. Thanks, as always, to Scott King for his help.

The second photo is of a Dot-tailed Whiteface. I found this species in Dakota County and made a post on 6 October 2011. On Friday, a male flew up from a duckweek-filled pond and, in midair, attached himself to a female. In a fraction of a second, the pair assumed a "Wheel Position." The two Whitefaces, now in tandem, landed back on the pond.

Kurt Meade (Dragonflies of the North Woods) writes, "mating is usually initiated by the male who, with the grace of a professional wrestler," curves his abdomen forward, and attaches the end to the back of the female's head. This behavior is to assure no other males visit his mate. The female then obtains sperm by attaching the end of her abdomen to his sexual organ. Sperm transfer is accomplished only after he purges other males' sperm from her genital opening. Meade concludes, "the time needed to complete fertilization ranges from 15 seconds to well over an hour."

Chalk-fronted Corporal

Yesterday Erika and I chased dragonflies at the University of Minnesota Landscape Arboretum. We found one new for us, a Chalk-fronted Corporal. (Presumably the name "corporal" comes from the stripes on the thorax.) This species, found across southern Canada, dropping down through California and also the northeastern United States, can be very common. They breed in bogs and woodland ponds--you may note by the leaves in this photo that our corporal was in a forested area. They tend to lay in wait for mosquitos and blackflies. Chalk-fronts tend to be aggressive species. Males will guard their females after copulation. After depositing her eggs in standing water, the females often fly into nearby woods (Dragonflies of the North Woods; Dragonflies and Damselflies of the East).

Northern Mockingbird

Erika took this photograph of a Northern Mockingbird at Santa Ana National Wildlife Refuge near Mission, Texas. Mockingbirds are found throughout the United States and most of Mexico. Although they are becoming less common in southern parts of their range, mockingbirds have been increasing in the north. They are occasionally reported from Minnesota, the Dakotas, and even southern Canada.

Their spread northward is attributed to increasing suburbs and secondary habitats. Mockingbirds will eat almost any fruit or arthropod. Both male and female mockingbirds sing. Males often sing over 150 distinct song types, which change and increase as birds age (Farnsworth et al. 2011). They imitate other bird songs and even non-avian species. I have heard mockingbirds imitate the sounds of passing trains. One explanation is that, as mockingbirds are omnivores, their varied repertoire discourages competition from other birds in the neighborhood.

Long-billed Thrasher

Long-billed Thrashers were common at Santa Ana National Wildife Refuge near Mission Texas. The species ranges from southern Texas through eastern Mexico. In Texas, it is most abundant in the Rio Grand Valley, where the bird has suffered from habitat destruction. Long-billed Thrashers (above) are similar to Brown Thrashers (below). This similarity has led ornithologists to assume that the two species also share similar behaviors, and thus the Long-billed Thrasher remains poorly studied (Tweit 1997).

Differences between the two species include the amount of white at the base of the lower mandible--all dark in the Long-billed Thrasher, half whitish or yellowish in the Brown. Long-billed Thrashers tend to have darker backs than do Brown Thrashers. Notice the unstreaked undertail feathers on the Long-billed Thrasher. Finally, Long-billed Thrashers have blacker streaking on their underparts than do Brown Thrashers. The Brown Thrasher in the lower photo was taken near Dundas, Minnesota.

Hooded Merganser

Although male Hooded Mergansers are stunning, hens are ducks with unruly coiffures. Erika and I encountered this bird in early May along the Cannon River near Northfield. Breeding across most of Minnesota, our bird may have been a migrant or a summer resident. In any event, females pick and maintain nesting cavities. They readily use nest boxes. These sites are often selected the season previous to their use. Drakes abandon their mates as the hens begin incubation, which lasts for about a month. Once hatched, the young remain in the nest for only a day (Dugger et al. 2009).

Sapsucker on a Wire

On 7 May 2012, John H. and I were birding near Dundas, Minnesota. I heard the the unmistakable, persistent, call of a Red-breasted Nuthatch. To show off to John my prodigious ability to recognize bird calls (and secretly affirm my identification), I played a screech-owl tape from my phone. Up flew this Yellow-bellied Sapsucker, and landing on an overhead telephone wire--an odd pose for a woodpecker. Not far behind, the nuthatch flew into a nearby spruce, thus keeping my bird call recognition reputation intact.

The nuthatch is probably a migrant in Rice County. This species breeds in northeastern Minnesota. Birds in Minnesota lists breeding records south to the Twin Cities, which are a couple of counties north of us. The sapsucker breeds across most of Minnesota, although it is more common the farther north you travel.