September 2019

Saltmarsh Sparrow on the Breeding Grounds

By in Conservation, Hybrids, Migration, Reproduction, Species Accounts

Nature is fascinating because it defies generalization. A biologist has to use the word all carefully. The statement that all mammals have hair is belied by the hairless condition of naked mole rats. The claim that all butterflies and moths (180,000 species) sip nectar or rotting plant material is put paid by a genus of moths that have gone the way of vampires, piercing and sucking the blood of mammals.

With over 10,000 species, birds provide many examples of generalization-busting examples. In today’s column, the Saltmarsh Sparrow will be our focus. This species is unique in being the only songbird that is an obligate resident of intertidal salt marshes. Its breeding range stretches along the Atlantic Coast from the expansive tidal marshes of the Delmarva Peninsula to Knox County here in Maine.  Their breeding range is more like a string of pearls than a continuous band. Suitable nesting marshes are not continuous along the coast.

These sparrows are migratory over most of their range, wintering in tidal marshes from northern Virginia down to central Florida along the Atlantic Coast with some wintering on the upper Gulf Coast of Florida.

A good place to see this rather secretive species is to walk the Eastern Trail through Scarborough Marsh. These sparrows are drab, even by sparrow standards. The birds have a flattish head with an orange stripe above the eye and an orange mustache (malar stripe). The breast is buffy with streaks.

The species has an interesting taxonomic history. Nelson’s Sparrow, a species which nests in Maine from Cumberland County to Washington County, was formerly lumped with Saltmarsh Sparrow and called Sharp-tailed Sparrow. Thanks to the work of Jon Greenlaw and others at Scarborough Marsh, we now know that two species were improperly lumped into Sharp-tailed Sparrow. The Check-list Committee of the American Ornithological Society split Sharp-tailed Sparrow in 1995.

The reliance on tidal marshes is hardly the only exceptional facet of the biology of Saltmarsh Sparrow. We think of songbirds as being monogamous birds with both parents sharing parental duties. A male stakes out a territory and defends it against intruding males and predators. Although we know that cheating on one’s mate occurs when the opportunity arises, faithfulness to one’s mate is the rule.

Saltmarsh Sparrows are different beasts in these regards. Males do not maintain nesting territories. Rather, each male has a home range within in which it lives, but home ranges of males overlap.  Aggressive interactions between males are rare, quite a difference from other songbird species. A male wanders through its home range, seeking receptive females to mate with. The male provides absolutely no care to the young that it fathers.

Any female is likely to be found in the home range of many males so promiscuity is common. A nest with offspring sired by a single father is rare in this species.

Although this unusual nesting strategy is well documented, we do not understand why these birds have diverged from the typical territorial nesting of other songbirds.

Saltmarsh Sparrows are not faring well. The population has been declining for the past 15 years, resulting in an 80% reduction of the population to leave only 30,000 birds. It is listed as a Species of Special Concern in Maine with similar designations in other states.

Nest failure results from inundation of the marshes during the highest tides of the tidal cycle and from nest predation. Birds will quickly renest if high tides flood their nests to get a second chance.

Sea-level rise is a particular concern because it will exacerbate the threat of tidal flooding. Without management intervention, population models suggest the species could be extinct by the middle of this century.

Management plans are being developed with the goal of stabilizing the population at 25,000 birds. More information is available at:   https://acjv.org/saltmarsh-sparrow-2/

Changes to the AOU Check-list of North American Birds

By in Taxonomy

Lots of birders and ornithologists keep an eagle eye out in the summer for the annual supplement to the AOU Check-list of North American Birds. This check-list is maintained by a committee of distinguished ornithologists well-versed in avian taxonomy and morphology. These scientists constitute the North American Check-list Committee (NACC) of the American Ornithologists Society.

The charge of this committee is to evaluate recent changes in distribution of North American birds and research on variation in species. They then amend the list of common and scientific names of our birds based on this research. The committee also sets the order in which species are listed to reflect current understanding of the relatedness of different species.  The NACC accepts proposals from anyone but proposals but must be strongly argued to receive NACC support.

Birders who are active list-keepers are keen to read the annual report because one’s life-list can be affected by NACC decisions. For instance, Thayer’s Gull was combined with Iceland Gull a few years ago, so many birders saw their life-lists decline by one species. But a split of Winter Wren into the eastern Winter Wren and the western Pacific Wren gave some birders an arm-chair life-bird.

This year’s report had little effect on North American life-lists. White-winged Scoter was split into three species but only one of those occurs in North America. The new species split off are called Velvet Scoter found in western and central Eurasia and Stejneger’s Scoter found in northeastern Eurasia and occasionally in Alaska. Our species remains the White-winged Scoter.

The only other change affecting Maine birds moving Tennessee Warbler, Nashville Warbler and some storm-petrels into a different genus and changing the check-list order of plovers, swallows and sparrows. A concise summary of the changes can be found at:

http://blog.aba.org/2019/06/aos2019.html

To me, some of the proposals that were not accepted were thought-provoking. One proposal advocated changing the common name of Salt Marsh Sparrow to Peterson’s Sparrow to honor the contributions to ornithology of Roger Tory Peterson. Accepting that proposal would set a new precedent. No bird has been described with petersoni as its species name. As well-meaning as this proposal might be, I am not surprised that it was rejected.

On the western plains, McCown’s Longspur is a common member of the New World sparrow family. It’s scientific name is Rhynchophanes mccownii. The species is named after Captain John Porter McCown of the U.S. Army. In 1851, McCown shot at a flock of Horned Larks and discovered he had killed a different bird as well as many larks. He gave the specimen to the ornithologist George Lawrence. Lawrence described the new species and named it after McCown. Note that McCown was not an ornithologist and collected the bird inadvertently. Nonetheless, the scientist who describes a new species has the right to attach a species name of her/his choice.

The person who sent a proposal to the NACC asked that McCown’s name be stripped from the common name. The reason is that McCown resigned his U.S. Army commission in 1861 and joined the Confederate army. The proposer argues that the American Ornithologist Society needs to promote the inclusion of diversity by not recognizing someone who promoted slavery.  The NACC was not compelled to change the common name. Even if a new common name was assigned, the scientific name would have to remain mccownii.

Ted Floyd, the editor of Birding magazine, proposed a change in spelling for common names honoring people. His argument is that the possessive form of the name is grammatically peculiar and misleading. Cooper’s Hawk is not a hawk owned by Cooper. Floyd argues that Cooper Hawk should be the form used. We do not use the possessive form in other uses: Washington County, Kennedy Memorial Drive, Douglas fir, Heimlich maneuver, Mark Twain Prize. He argued we should use Swainson Thrush, Bonaparte Gull and Lincoln Sparrow. I found his arguments compelling but the NACC rejected his proposal.