Tonight I am sharing a few miscellaneous shorebirds. First up to bat is a shorebird that isn’t much of a shorebird at all – the Upland Sandpiper. So named due to its preference for higher and drier habitat, the Upland Sandpiper can be found in fields and meadows. Look for it on a typically elevated perch and find it by its haunting song.
With a ratio of what must have been close to 1000:1, the Wilson’s Phalarope greatly outnumbers any other Phalarope. However, Steve and I were still able to find and ID a couple of Red-necked Phalarope in winter plumage, as pictured above.
A true wetland favorite, the Black-necked Stilt is as pleasing to watch for its behavior as it is a piece of natural art.
As stout and cute as a Bulldog puppy, Willets are always a site for sore eyes.
On our last evening and during our very few hours of decent, golden hour light Steve and watched a number of Willets and Avocets feeding in the shallows near the road.
With unique coloration and behavior, the Ruddy Turnstone is a shorebird that does not take a second guess to identify. The photograph above captures this conspicuous behavior for which these birds have earned their name. They do turn anything that they can – looking for any type of small invertebrate that may be hiding underneath. Anything includes dead fish or other animals, shells or trash washed up on a beach.
These guys typically migrate along the coasts and finding them in the interior is not that common. Although we missed out on finding any Buff-breasted Sandpipers during this visit, we were glad to have the opportunity to watch these guys in action.
Considered conspecifics for decades, both the Long-billed and Short-billed Dowitchers breed in the high arctic. Differences in plumage, migratory routes and breeding isolation, followed by allozyme and mtDNA evidence suggested separate species status. The Long-billed, pictured in this post was the only Dowitcher species Steve and I were find at Quivira. This is not altogether surprising due to the Long-billed’s preference for freshwater during migration and the Shirt-billed’s tendency to stick to marine environments.
The long, thick legs and bill give indication as to the depth of water in which these birds feed and they probe for prey using a rapid up and down motion that is quite reminiscent of the action of a sewing machine.
A medium sized, markedly-colored Calidris sandpiper, the Sanderling is one of the most highly traveled migrant birds on the planet. Breeding only in the far north arctic, some Sanderlings will winter as far south as Cape Horn of South America. Individuals in breeding plumage are easily identified with close enough inspection by looking for the rusty-gravel coloration. Winter and juvenile forms are contrasty black and white. All birds lack a back toe, which are typically found on shorebirds.
Peeps, or “stints” if you find yourself in the old world refer to a group of small shorebirds in the genus Calidris (formally Erolia). The smallest of the peeps, and therefore, all shorebirds is the Least Sandpiper, which is also one of the more abundant shorebirds to travel through the interior of the United States on its way to its near-arctic nesting grounds.
Peeps are notoriously difficult to identify, but much depends on the circumstances. During winter, with few other species or birds available for comparison, it can be quite difficult. In breeding plumage, with other Calidris species in near proximity, proper identification will be easier with a little practice. There are plenty of resources to help you with identification, so I will not repeat those here. The Least Sandpiper is one of the more tame of the shorebirds, often coming quite close to a patient birder.
The Phalaropes are quite the interesting group. First of all, two of the three species are considered pelagic – meaning they spend a great part of their time out at sea, away from visible land. The Wilson’s Phalarope, pictured throughout this post was the most abundant of the shorebirds during our visit to Quivira NWR, and do nest within the refuge. The Phalaropes exhibit reverse sexual dimorphism – both in visual and behavioral characteristics. This means that females are the more brightly colored of the sexes. Similarly, the females display and fight for males. The males will immediately take over the responsibilities of incubating the eggs and raising the chicks, while the polyandrous female will attempt to find and mate with other males. See the photo below of a relatively drab male with his mate.
After reading of this role reversal in a field guide recently, of course I had to find out why. This is not an easy one to answer. Do a quick search and terms like Operational Sex Ratio (ratio of sexually active males and females in a given time and place) and Potential Reproductive Rate (potential offspring production rate if mate availability is unlimited) and Bateman’s Principle (in most species, reproductive success is more variable in males than in females – primarily due to anisogamy) come up often.
So what forces add up to cause this reversal in sexual selection (females competing for males – males choosing females)? Ultimately, this is quite a complex question to answer, and I cannot begin to cover all possible variables that affected this change. The primary changes that had to occur in these species is that OSR of males and females had to be skewed to a situation where females outnumber males in mating opportunities. This produces a scenario where females are forced to compete for males. There are anecdotal accounts of males actually competing for females in this species when the OSR switches to favor males (although males still kept their brood-rearing responsibilities). Another aspect to this model is that PRR must shift so that females can reproduce at rates close to that or greater than males. For instance, nesting sites should not be limited based on other resources. And, similar to traditional sex role systems, the male must be pretty certain that the eggs and brood he will be caring for are his. Observational reports confirm very few extra pair copulations/fertilizations occur in species where this role reversal has developed.
I must admit I only have a hint at the factors that go into creating sexual role reversal in these birds. Obviously there are important endocrinological and physiological changes that must go with the social and environmental changes. Here are a few of the sources that I have used to get these thoughts together. I look forward to learning more about this interesting phenomenon.
Marcel Eens, Rianne Pinxten. Sex-role reversal in vertebrates: behavioural and endocrinological accounts. Behavioural Processes 51 (2000) 135–147.
Ingrid Ahnesjö , Charlotta Kvarnemo, and Sami Merilaita. Using potential reproductive rates to predict mating competition among individuals qualified to mate. Behavioral Ecology (2001) 12 (4):397-401.
Hanna Kokko and Pat Monaghan. Predicting the Direction of Sexual Selection. Ecology Letters (2001) 4: 159-165.
Mark A. Colwell. Shorebird Ecology, Conservation, and Management. University of California Press, Oct 17, 2010.