The Black-bellied Plover is a plump, medium sized shorebird with a lurching gait and healthy appetite for polychaete worms. It commonly haunts the intertidal mudflats ranging the globe with little discrimination among temperate or tropical climates, but when the breeding season rolls around this marathon migrant takes to the wing in search of high arctic tundra. During migration and on the breeding grounds a conspicuous black and white plumage leaves little doubt to its identity. At other times one must tease the subtler field marks from its nondescript gray attire. Black armpits are its year round signature. It sports a stubby bill and large black eyes adept at nocturnal and diurnal foraging alike. Quick to flush and cause a ruckus, this plover has top notch sentinel acuity, often relied upon by its mudflat neighbors.
Weight: 8 oz
Black-bellied Plovers are the largest North American plover, and medium sized among shorebirds. They show very slight sexual dimorphism in size, with females being larger (Pyle, 2008). They have distinctive juvenal, basic, and alternate plumages ranging from cryptically mottled to a conspicuous, high contrast nuptial attire (Sibley, 2014).
Black-bellied Plovers sport a stout, teardrop-shaped body with a large head and short neck, all situated atop dark gray legs that are neither short nor long. The head is round yet blocky depending on the angle, with a short but robust, blunt-tipped bill and large black eyes. Wings are long and built for speed, providing Black-bellied Plovers rank among the fastest of shorebirds (Poole, Pyle, Patten, & Paulson 2016). The folded primaries project beyond the tail, creating a very pointed appearance to the rear end. The Black-bellied Plover strays little from standard Charadriidae profile, however, typical posture is more upright than many small plovers.
In all plumages a few notable qualities distinguish Black-bellied Plovers, especially from their congeners the Golden Plovers. Black axillaries (armpits) are conspicuous and contrast against a mostly white underwing, especially in flight or when stretching on land. White bases of the secondaries and inner primaries form bold wing stripes that are also easily noticed in flight. Although Golden Plovers show similar stripes, theirs are weak and indistinct in comparison. A mostly white tail with dusky black banding towards the tip is also unique. The stout bill is thicker and proportionally larger than that of other Pluvialis plovers. And lastly, the dorsal surface of Black-bellied Plovers is mottled gray and white (basic plumage), or black and white (alternate plumage), but almost always lacking in golden tones, the namesake of Golden Plovers.
Basic Plumage: Contour feathers of the upper side are grayish brown with white edging, giving a low contrast speckled appearance. The underside is white, with exception to the breast which usually has a mottled dusky gray wash, lighter than the back. The head is mostly gray with pale white highlights on the chin, lores, forehead, and supercilium. Contrast between the pale supercilium and darker crown gives a capped impression. Dusky auriculars sometimes create a highlighted ear spot.
Alternate Plumage: For the breeding season male Black-bellied Plovers don a spectacular, high contrast black and white plumage. The crown, nape and hind neck become white. Its namesake black belly is crisply defined and wanders up the throat to cover the face, creating a black mask. The mantle is covered with a thick spattering of black and white markings, much larger and with more contrast than shown in basic plumage. Females acquire a much subtler version of this alternate plumage retaining many characteristics of their nonbreeding attire, while gaining a vague impression of a black face and belly.
Immature Plumages: Juvenal and formative plumages superficially resemble definitive basic plumage, but may show higher contrast speckling to the upper parts and more extensive streaking on the breast and belly. Some may show hints of yellow on the upper side when feathers are fresh, fading quickly, and never to the extent of Golden Plovers.
Primaries (full length): 10
Secondaries including Tertials: 16-17
(Poole et al., 2016)
Black-bellied Plovers are typically considered to have a complex alternate molt strategy. They go through a complete prebasic molt, which may begin on the breeding grounds, but mostly takes place after fall migration on the wintering grounds (Pyle, 2008). A partial prealternate molt occurs primarily on the wintering grounds prior to spring migration, but may also complete at stopover sites along the way or once on the breeding grounds (Pyle, 2008). Whether or not first cycle birds have both preformative and prealternate molts is still a point of uncertainty. Research by Howell and Pyle (2002) suggest there may be only one protracted molt during the first winter with qualities phenotypically more similar to a prealternate molt. This may be evidence of the evolutionary merging of preformative and prealternate molts in ancestral species (Pyle, 2008; Poole et al., 2016). If this is the case Black-bellied plovers would instead have a simple alternate molt strategy.
Molt timing and sequences differ among populations of Black-bellied Plovers and corresponds with their associated wintering latitudes, exhibiting either northern hemisphere or southern hemisphere strategies (see distribution) (Pyle, 2008). Molt timing and extent among these two strategies, seen interspecifically among southern hemisphere migrants, is thought to reflect differing abundances of daylight and food resources during the simultaneous boreal winter and austral summer, suggesting environmental factors have been more influential than phylogenic factors in shaping these strategies (Pyle, 2008). The wintering population common to the Pacific Northwest exhibit a northern hemisphere strategy characterized by a rapid, complete prebasic molt during mid summer and fall (Pyle, 2008). In contrast, birds that winter in the southern hemisphere typically show protracted prebasic molts, completing after fall migration or at stopover sites along the way (Pyle, 2008).
A further selective force shaping molt strategy among long distance migrants is the consideration of wear. As fitness is often directly linked to plumage quality via intra and interspecific sexual selection, birds like Black-bellied Plovers that form pair bonds on the breeding grounds must show up in the highest quality plumage (Lourenco & Piersma, 2015). Completion of prealturnate molt at stopover sites close to the breeding ground is therefore a beneficial strategy for separating the costs of migration and molt, while reducing potential migratory feather wear (Lourenco, 2015).
Research by Jukema, Tulp, and Bruinzeel (2003) comparing molt patterns between Pluvialis plovers suggests an interesting correlation between nest defence behavior and prebasic molt timing. While Black-bellied Plovers employ aggressive nest defence, Golden Plovers tend towards the opposite strategy, relying heavily on camouflage to avoid detection (see Breeding) (Jukema et al., 2003). Interestingly, Golden Plovers begin molting contour feathers of the sides and flanks during early stages of incubation possibly providing increased camouflage, specifically where the incubating adult’s body meets the nest (Jukema et al., 2003). In contrast Black-bellied Plovers retain their conspicuous breeding plumage throughout the full incubation period (Jukema et al., 2003). In the case of Black-bellied Plovers, retaining bold plumage is thought to actually benefit aggressive nest defence, and therefore an early molt into more subdued plumage would gain no advantage (Jukema et al., 2003).
Ubiquitous throughout the globe, this high arctic breeder can be found nesting well above treeline among the tundras of North America, Asia, and Europe (O’Brien, Crossley, & Karlson, 2006; Dunne, 2006). In contrast to such a narrow breeding range, fall migrations distribute Black-bellied Plovers coastally over a wide latitudinal range from temperate southern British Columbia, Canada, throughout the tropics, continuing to southern South America, and include analogous zones around the globe (O’brien et al., 2006). Widespread to say the least.
Breeding distribution within North America occurs from the coastal plains of western and northern Alaska, across northern Canada (mainlands and islands), including southern Baffin island (Dunne, 2006; Poole et al., 2016). Nonbreeding distribution widespread along Pacific, Atlantic and Gulf coasts, with a northern limit around southern coastal British Columbia (Dunne, 2006; Poole et al., 2016). During Migration Black-bellied Plovers move through interior North America in lesser abundances, primarily through the Great Plains and eastern states (Poole et al., 2016).
Throughout the nonbreeding and migratory season Black-bellied plovers are common along outer coastal beaches and the two large estuary systems of Grays Harbor and Willapa Bay, however, distribution within the Puget Sound is limited to a select few locations (Buchanan, 2006). Of these, Totten Inlet regularly holds very high densities, possibly the highest in the state, with a count during the 2002 migratory season showing 1,032 birds (Buchanan, 2006; Buchanan, 2011). Luckily, this location is only 15 minutes from TESC heading NW on US-101.Other important locations within the Puget sound include tidal ecosystems associated with the Dungeness, Samish, and Stillaguamish Rivers (Buchanan, 2006).
For those wishing to see Black-bellied Plovers near Evergreen, KGY Point at the northern tip of downtown Olympia can be a great location. At low tide a sizable intertidal mudflat with close range viewing opportunities often attracts many plovers, Dunlin and more.
(Poole et al., 2016)
Migration is largely concentrated to the coasts, with movements through interior regions in lesser abundances (Poole et al., 2016). Although birds of all age and sex classes migrate together, distributional differences exist between them, with immature birds wintering the furthest south, and adult females wintering further south than adult males (Poole et al., 2016). Additionally, immature birds may oversummer, remaining on their non breeding grounds until they reach sexual maturity, typically by their second year (Poole et al., 2016).
Migrating Black-bellied Plovers reach their greatest concentrations in the Pacific Northwest from late April to early May, with peak numbers in the southern Puget Sound at locations such as Totten Inlet between the 13th and 18th of April (Buchanan, 2006; Buchanan, 2011).
Black-bellied Plovers are among many long distance migrants that require stopover sites along their journey to replenish energy sources, rest, or wait out unfavorable weather (Tan, Choi, Peng, Melville, & Ma, 2018). Behaviors at the sites are driven by both endogenous and exogenous factors that vary in extent with relation to breeding schedules, becoming more endogenously driven as time constraints narrow (Tan et al., 2018). In a study by Tan et al. (2018) findings suggest that the Black-bellied Plovers at final pre-breeding stopover sites are less concerned with environmental constraints when making departure decisions compared with earlier stopover locations, suggesting a stronger internal driving force. Another finding of this study suggests smaller birds benefit from forming larger flocks and departing at night to reduce predation pressure and increase diurnal feeding opportunity. In contrast larger species in the study such as Eurasian Curlew and Bar-tailed Godwit, generally formed smaller flocks and were less restricted to nighttime departures.
Nests in high arctic tundra lowlands of both coastal and inland placement and seems to accept a wide variety of microhabitats within the greater tundra ecosystem including tundra wetlands and dry heath (Poole et al., 2016).
Non breeding and migration:
In winter largely restricted to coastal and estuary ecosystems with abundant intertidal mudflats. May also forage among flooded agricultural land in proximity to coastal habitats when conditions are not favorable. During migration many birds move through the North American interior and must rely on freshwater systems such as lakes and reservoirs for feeding opportunities (Poole et al., 2016). In the south Puget Sound at high concentration sites such as Totten inlet, Black-bellied plovers have been observed roosting in tracts of saltmarsh vegetation surrounding their typical intertidal mudflats feed sites (Buchanan, 2006).
On their breeding grounds Black-bellied Plovers utilize multiple feeding opportunities, foraging among open tundra both within and outside of their nesting territory, sometimes at communal sites (Poole et al., 2016; Smith, Gilchrist, & Smith, 2007). The prefered menu at these dry heath or wetland tundra microhabitats includes flies, beetles, and spiders, as well as small freshwater bivalves and occasionally plant matter including berries (Poole et al., 2016).
In temperate wintering regions polychaete worms make up the bulk of their diet, while in tropical regions they may consume large amounts of small crabs, particularly fiddler crabs (Hugie, 2004). The visually responsive stop-run-peck-run foraging strategy employed by the Black-bellied Plover is thought to be a limiting factor in the exploitation of a wider array of prey sources compared with other shorebirds who are not as specialized in foraging behavior (Rowell-Garvon, & Withers, 2009).
For Plovers wintering at temperate latitudes diurnal foraging is quite limited given the short photoperiod. For this reason Black-bellied Plovers must turn to nocturnal foraging to sufficiently balance energy budgets (Dwyer, Bearhop, Campbell, & Bryant, 2013). At night other shorebirds rely on their long, highly tactile bills to find food, however, Black-bellied Plovers do not share these morphological features, and instead use their very large eyes to visually find prey items (Dwyer et al., 2013; Poole et al., 2016).
Analysis of energy budgets in diurnally foraging Black-bellied Plovers is shown above. Fifteen foraging individuals were filmed for 1 minute intervals at KGY Point, Olympia, WA. Recordings were then analyzed to determine the amount of time spent actively moving in pursuit of prey items versus time spent in a stand still position, presumably visually searching for prey. The results show a trend in favor of increased pausing time over moving time in this representative sample. Further studies will be of comparative value, especially among a variety of foraging substrates and environmental conditions.
Black-bellied Plovers are hyper vigilant predator detectors and quick to become vocal- “pee-o-wee, pee-o-wee”. Red Knots take advantage of this by foraging nearby, using plovers as a sentinel. Black-bellied Plover alarm call are also known to provide cues to Dunlin, who readily take to the air in predator avoidance flights at the onset of plover calls (Poole et al., 2016).
Traversing their mudflat smorgasbords, Black-bellied Plovers employ a lurching, almost cliché, stop-run-peck-run foraging style familiar among so many Charadriidae. They visually inspect the soupy intertidal substrate for prey items, make a hurried advance, sometimes abruptly pausing to recalibrate, then before you know it a six-inch bristle worm is being carefully stretched from its subterranean hideout to meet plover gizzard. They will trudge ankle deep in muck or cruise drier substrates, but rarely venture past the waterline to forage.
Loosely associating with their conspecifics, Black-bellied plovers wander in all directions lacking the synchronization of the small Dunlin who are likely probing nearby. Most times they prefer a breadth of elbow room, keeping a respectable spacing among themselves. At other times toleration is heightened and foraging groups become more cohesive, yet still disorganized.
When a large bristle worm dangling from the bill catches the eye of that lurking Glaucous-winged Gull, things are about to get noisy. Alarm calls simultaneously ring out among the flock…pee-o-wee, pee-o-wee! The Black-bellied Plover’s great speed and agility in fleeing flight may test the gull’s kleptoparasitic integrity, but many times thievery is successful. It’s just part of life as a Black-bellied Plover.
On the wintering grounds aggressive behaviors may be used to maintain foraging territories or instead mutual avoidance strategies may mitigate the need by providing sufficient spacing among individuals (Buchanan, 2011). The strategy used in a given situation is a function of prey intake maximization, thus for a visual forager such as a plover, it may at times be more beneficial to increase foraging time and decrease territorial encounters, which also run the risk of disturbing prey items (Buchanan, 2011). In sites of high density such as Totten Inlet, Washington, it has been observed that plovers may engage in aggressive, territorial behavior more frequently, suggesting mutual avoidance strategies have become less efficient and competition for prey items is most important (Buchanan, 2011). At this same site Bachanan (2011) reports behaviors during peak migration including torpedo runs, parallel walks, wing hanging and targeted flight displays, behaviors in conjunction typically associated with breeding season and grounds. As these behaviors are unknown for Black-bellied plovers south of their breeding range, the author posits an agonistic nature, possibly in correlation with high densities of individuals at this site. However, if these are instead misplaced breeding season behaviors, these observations are the first of their kind (Buchanan, 2011).
Defense of breeding territory is both intra and interspecific, especially among the closely related American and Pacific Golden Plovers who utilize similar, but not overlapping, nesting habitat, suggesting the efficacy of territorial interactions between these species (Poole et al., 2016).
To maintain breeding territories males engage in a behavior termed the parallel walk, behaving as the name implies by walking alongside intruding males who broach the boundaries of their territory, especially after eggs have hatched when boundaries begin to deteriorate (Buchanan, 2011). They also take to the air and perform butterfly flight displays, laying claim to the land below (Poole et al., 2016 ). Iterations of these flight displays are also used in courtship interactions (see Breeding).
As extremely vigilant parents, Black-bellied plovers are easily flushed from the nest at great distances (up to 250 m) at the approach of possible predators (Poole et al., 2016; Smith et al.,2007). Both parents aggressively mob potential threats of both aerial and terrestrial pursuit, including Jaegers and Arctic Foxes, respectively, having significantly less success deterring mammalian predators (Smith et al.,2007).
Distraction displays are also among their bag of tricks, but unlike the readily observed hurt-wing antics of Killdeer, Black-bellied Plovers run hurriedly away from the nest with drooped wings and lowered head, pausing, then settling into the new location suggesting a nest below. At times they may also gain a predators attention by beating their wings in spasms that noisily contact the ground, while simultaneously stomping their feet (Poole et al., 2016)
On their breeding grounds Black-bellied plovers are seasonally monogamous and biparental, sharing the duties of incubation, brooding, and feeding (Smith, Gilchrist, & Smith, 2007). Both sexes aggressively defend their nest and young, unlike their congeners who instead rely more heavily on cripsis and distraction displays to thwart predation (Jukema, Tulp, & Bruinzeel, 2003).
Pair formation takes place after sexes arrive independently on the breeding grounds (Buchanan, 2011; Poole et al., 2016). Males gain the attention of potential mates through both aerial and terrestrial displays (Poole et al., 2016). Aerial displays often consist of slow, hesitant, fluttered wingbeats over the nesting territory, known as “butterfly flight,” and rapid, back and forth rotation of the body on its central axis, termed “zig-zag flight” (Poole et al., 2016). Ground displays are characterized by “torpedo runs”, rushing toward and pausing before an intended mate, with bill to the ground and fanned tail pointed skyward, often followed by copulation attempts (Buchanan, 2011; Poole et al., 2016).
Nest Site and Construction:
Nest construction is also a joint effort. Males select the site, showing a preference for exposed substrates consisting of cryptobiotic soil crusts, lichen, and rock, then begin a simple scrape (Poole et al., 2016; Smith et al.,2007). The female adds her finishing touch, lining the shallow depression sparsely with bits of vegetation litter and small stones (Poole et al., 2016).
Eggs and Incubation:
Eggs are pyriform in shape, pink to brown in base color with crisp black-brown speckling, and nearly alway come in a clutch of 4 (Poole et al., 2016). Males typically begin the incubation process before the clutch is complete, resulting in asynchronous hatching (Poole et al., 2016). Once the clutch is complete, incubation is shared evenly between the sexes, both showing highly developed brood patches (Poole et al., 2016). Hatching time has been observed ranging from 23 to 27 days (Poole et al., 2016). In the event of nest predation, replacement clutches are rare, with only one reported attempt (Poole et al., 2016; Smith et al.,2007).
From the moment the first chick hatches it takes less than a day for the entire brood to depart the nest, sometimes remaining through their first night (Poole et al., 2016). Precocial young hatch with a full covering of down and soon thereafter forage for themselves without help from their parents (Poole et al., 2016). Once the last chick is mobile, parents lead the young away from the nest site to suitable foraging areas, often with more vegetation (Poole et al., 2016). At this point parental care consists of brooding for the first 2-3 days, which is shared between parents (sometimes simultaneously), and alerting the young to nearby predators, in which case chicks crouch and become motionless (Poole et al., 2016). Young gain flight abilities around 23 days after hatching, which is short compared to other shorebirds of similar size (Poole et al., 2016). Females are reported to desert young anywhere from 10 to 21 days after chicks hatch, leaving the male to fulfill remaining parental duties (Poole et al., 2016).
Both adult and young Black-bellied Plovers face a range of predation pressure on their tundra breeding grounds. For adults the main threats include aerial predators such as Peregrine Falcon, and Snowy Owl (Poole et al., 2016). Eggs and young are especially susceptible to Jaegers, large gulls such as Glaucous and Herring Gulls, and Arctic Fox (Smith et al.,2007). Additionally, rates of nest failure correlate specifically with predator-prey cycles between Lemmings and their predators (Smith, Gilchrist, Forbes Martin, & Allard, 2010). During cycles of low Lemming abundance every 4 years on average, predators such as Arctic Fox and Jaegers rely more heavily on bird eggs and young, including those of Black-bellied Plovers (Smith et al.,2007).
To minimize these risks, Black-bellied Plovers use a combination of visual acuity and exposed nest sites for early predator detection, flushing at distances greater than 20 meters to aggressively attack predators that enter their nesting territory (Jukema, Tulp, & Bruinzeel, 2003; Smith et al.,2007). These conspicuous tactics set the Black-bellied Plover apart from its Pluvialis congeners, who are hesitant to flush, and rely more on crypsis and distraction displays to deter predation (Jukema, Tulp, & Bruinzeel, 2003). These behavioral differences may also reflect molt differences among the Pluvialis plovers (see Molt section).
A Biparental breeding strategy may also contribute to lowering rates of predation. Smith et al. (2007) suggest that shared incubation duties between males and females reduces activity at the nest site, thereby minimizing the chance of divulging its location to predators.
Analysis of Christmas Bird Count data for Washington over the last 10 years shows a slight rise in Black-bellied Plover abundance. However, analysis of all three west coast states together shows an overall decline. Note the multi state graph is for the past 5 years only.
According to Andres et al. (2012) recent surveys conducted by the Program for Regional and International Shorebird Monitoring (PRISM) have greatly improved North American estimates of Black-bellied Plover abundance, especially that of the subspecies P. s. Squatarola, which breed in Alaska. PRISM results from 1997-2007 suggest a combined breeding population of 314, 293 for Alaska and Canada, with high densities in the National Petroleum Reserve in northern Alaska and the small islands to the west of Baffin Island, Canada (Poole et al., 2016). However, historical migration counts for this species have been too variable to suggest any significant population trends, and the increases seen in abundances most recently are thought to reflect the more comprehensive surveys as of late (Andres et al. 2012). The other subspecies P. s. cynosurae, breeding in the Canadian arctic, was less thoroughly surveyed due to its range, and while estimates have improved, they are still believed to be conservative (Andres et al. 2012).
An important consideration for shorebird conservation is protection of stopover sites. Black-bellied Plovers are one example among many shorebirds who rely on stopover sites to rest and replenish during migration (Tan et al., 2018). According to Koch and Paton (2014), shorebird declines in North America have been linked to deteriorating quality of stopover sites, due to increasing anthropogenic disturbances affecting birds directly and indirect disturbances such as depletion of prey resources due to commercial harvesting. One such disturbance is the recreational use of off road vehicles, popular at many of these sites (Tarr, Simmons, & Pollock, 2010). Likewise, sea level rises over the next century are projected to severely reduce intertidal foraging habitat at many key stopover sites around the world, necessitating the need to protect and secure stopover habitat where possible (Koch, 2014). Furthermore, stopover sites are valuable to science for assessing population trends as well as phenological migratory shifts that may be indicators of climate change.
Local studies in the Puget Sound region have suggested a possible correlation between Black-bellied Plover population increases and restoration of natural Salmon runs via increased escapement. In a long term study at Totten Inlet, Buchanan (2006) showed a steady increase in Black-bellied Plovers during both breeding and nonbreeding seasons from the early 1980s to early 2000s. During this same time period concern for overharvesting Chum Salmon in the area lead to reductions in commercial fishing, which in turn significantly increased the salmon runs in both Kennedy and Schneider Creek, which flow into Totten inlet (Buchanan, 2006). The author suggests that nutrients from decomposing salmon carcasses have provided greater abundances of food sources, specifically Polychaete worms, which have bolstered Black-bellied Plover numbers. At other sites throughout the Puget Sound where salmon escapement did not change, Black-bellied Plover abundances remained stable, suggesting the trend at Totten inlet was site specific, and correlated with increased Chum spawns (Buchanan, 2006). As many shorebird species in North America are experiencing declines (Hargreaves, 2010), understanding relationships, like those seen with salmon, may be of great importance to future conservation efforts worldwide, as well as locally in the Puget Sound.
Black-bellied Plovers face a number of threats to their survival including those directly associated with humans such as habitat degradation and pollution, or indirectly such as the transformation of arctic ecosystems resulting from climate change (Hargreaves, 2010). As higher latitude nesting species, Black-bellied Plovers may have a heightened susceptibility to these effects in conjunction with energetically taxing and risky, long distance migrations (Hargreaves, 2010). Exposure to toxic substances associated with disproportional accumulation of industrial pollutants in typical feeding substrates such as estuarine sediment, is of great concern (Hargreaves, 2010), especially taking into account that Black-bellied Plovers are known to ingest large amounts of sediment along with their prey items (Poole et al., 2016).
In addition to pollution, the estuary systems around the world are increasingly under threat to land reclamation and damming of rivers (Dias, Leqoc, Moniz, & Rabaca, 2013). Damming acts as a blockade to sediment and freshwater flow into estuary systems, which changes the physical and chemical makeup downstream, often shrinking mudflats and increasing salinity concentration to unhealthy levels for prey items (Dias, 2013). Shorebirds are extremely vulnerable to these kinds of changes and fill and important role in the food chain as secondary consumers (Dias, 2013).
Kennedy Creek Natural Area Reserve
Oyster Bay, Totten Inlet
Mason Co., WA
47.099418, -123. 085874
10% Cloud Cover
Wind SW 5-10 mph in gusts
Tide 5.0’ incoming
At 1818 I surveyed the mudflats with my scope from a grassy area just below the Kennedy Creek Parking area beside US-101. My location had just lost sun for the evening but to NW about 150-200 yrds a large tract of mudflats were still in full light. In the immediate area there were no BBP. Way out to the NW on a small isolated mudflat about 100’ x 25’ within the main water channel was a group of 43 BBPL. They were spaced rather tightly, foraging in their typical halting manner. In the foreground along the edge of a very expansive mudflat was a flock of Dunlin of 250-300 individuals. Smaller portions of this group would often take flight, leapfrogging down the shoreline. The isolated mudflat with BBPL was quickly vanishing with the incoming tide and I was curious to see how long the birds would remain. The flushed just before water covered the flat, moving to the larger expanse near the Dunlin. When they flew to this new location the entire flock of Dunlin also took to the air, moving in wide banked synchronized turns just above the surface. At this point the BBPL moved out of my sight.
Kennedy Creek Natural Area Reserve
Oyster Bay, Totten Inlet
Mason Co., WA
47.099418, -123. 085874
Tide 5.25’ outgoing
At 1403 I surveyed the mudflats at the mouth of Kennedy Creek near the main parking area off of US-101. The flat across the river channel immediately to the north held a small group of 3 BBPL, and a scattering of small groups of Dunlin. 17 Killdeer were spread out across this area, as well as the higher bank just to the south, producing an almost constant stream of vocalization.
The 3 BBPL were spaced very far from each other, an average of maybe 50’, but at times also came within 5’. No interactions between individuals occurred that I was aware of. My goal was to get data on foraging efficiency. In three separate 10 minute intervals I observed each of the plovers, counting the amount of times they pecked the substrate and whether or not a bristle worm was captured. The first bird pecked 34 times, 10 of which worms were visibly captured. The second bird pecked 53 times and 14 worms were captured. The last bird pecked 36 times with only 8 worms captured. I found it hard to tell if smaller prey was indeed captured on bouts that produced no worm. Some of these pecks were followed by vibrations of the throat, seeming like a swallowing motion. I think next time I will need to devise a more structured way to observe this behavior.
Of special note, one of the BBPL was showing signs of molt on the sides of the breast, with small dark patches beginning to show.
Near Swantown Marina
Thurston Co., WA
Tide 6.2’ incoming
NE wind 1-2 mph
Light mix of rain/snow-intermittent
I did a quick survey of the mudflat at 1209 seeing 14 BBPL, 3 Dunlin, 1 GBHE, and a scattering of 7 Crows and 50+ various gull species, many of which were GWGU. The plovers were spread out among the 300×150’ mudflat, seeming to prefer wetter areas. Some were at the water’s edge, some were high up into the drained areas, but following little water channels that remained. I found it interesting that while foraging, most times they pause on one foot. I wonder if this increasing reactionary times when prey is spotted and movement begins again?
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This post was written by Bow Tyler as part of the Birds: Inside and Out program, Winter 2019.