Conservation and Management

Effects Of Human Activity

Major decline in American Golden-Plover population caused by excessive sport and market hunting during the nineteenth and early twentieth centuries (Osgood 1890;Cooke 1910; Forbush 1916, 1929;Wetmore 1927; Bent 1929; Mackay 1929; Allen 1934). Large numbers killed in North America, especially during mid-continental spring migrations. Estimates of 48,000 shot in a single day near New Orleans, LA, in spring 1821 (J. Audubon inBent 1929); 9,000 received by Boston game dealers in spring 1890 (extrapolated from Mackay 1891); and birds “for 25¢ a dozen,” many spoiling before being sold, in early 1850s in Portland, ME (Palmer 1949) are representative of the devastating effects of market hunting on this species.

Hunted also on South American winter range (Dabbene 1920, Hudson 1920, Wetmore 1927), but impact apparently much less than in North America (Canevari and Blanco 1994). Population rebounded significantly after most hunting ended around turn of century (1900). Limited evidence of subsequent population stability as numbers wintering in e. Buenos Aires Province, Argentina, showed no evidence of further decline over period 1927–1962 (Olrog 1967), and Isacch and Martinez (2003a) working at Medaland Ranch (an important Argentine wintering site) found plover population 1996-2000 of similar size to that recorded in earlier years by Myers and Myers (1979). To what extent the foregoing suggestions of stability apply elsewhere on the winter range is unknown. Loss of habitat, particularly on winter range (see below; also Habitat: winter range, above), likely has ruled out any possibility of recovery to pre-exploitation levels. For additional historical commentary see Johnson (2003), Clay et al. (2009).

Pacific Golden-Plover also hunted, but impacts mostly undocumented. Hunted (usually during spring) in Hawaiian I. until 1941, with daily bag limit of 15 often exceeded (Schwartz and Schwartz 1949). Various accounts described hunting techniques involving blinds located at watering sites and lamented declining populations (Wilson and Evans 1892, Henshaw 1902, Perkins 1903, Munro 1945, Schwartz and Schwartz 1949). With subsequent protection, Pacific Golden-Plover has recovered in Hawaiian I. Unfortunately, no data for comparison of past and present populations.

Both species either protected by law or otherwise unexploited in almost all of the Western Hemisphere. However, hunting of American Golden-Plover still occurs in Guyana, Suriname, French Guiana, and Barbados (Hutt 1991, Canevari and Blanco 1994, D. Blanco and A. Le Dreff in litt., Johnson 2003, Clay et al. 2009). Net effect of hunting in Barbados likely beneficial for shorebirds since this traditional activity gives incentive to preserve otherwise threatened wetlands (C. Faanes in litt., Clay et al. 2009). Pacific Golden-Plover protected from hunting in Australia and New Zealand (Lane and Sagar 1987). Commercialized exploitation of shorebirds very extensive in e. Asia, particularly China, Thailand, Vietnam,  Indonesia and Burma (Myanmar) (Ruttanadakul and Ardseungnurn 1986, Parish 1987, Alanzo-Pasicolan 1990,Bamford 1992, Barter 1993, Lu 1993, Tang and Wang 1995, Ma et al. 1998, Zockler et al. 2010); also trapped and sold in India (P. C. Bhattacharjee and V. Santharam in litt.). Total annual losses of Pacific Golden-Plovers to human predation in these regions unknown. About 2,000 killed/year in West Java alone (Milton and Marhadi 1989). For both species, disturbance caused by hunting, trapping, other factors (vehicles, tourists, dogs, etc.) may indirectly reduce feeding opportunities and decrease fitness (Madsen and Fox 1995, Blanco (1998).

Most breeding ranges of these plovers are intact and relatively unexploited by humans. However, the negative impacts of climate change (low growth tundra replaced by taller vegetation, shifts in timing of insect emergence, etc.) loom as major threats to the stability of arctic and subarctic breeding grounds (Lindström and Agrell 1999, Callaghan et al. 2004, Meltofte et al. 2007, Tulp and Schekkerman 2008). Increasingly, there are regional problems (oil drilling, mining, etc.), and Gill (1995) cautioned against the assumption that northern breeding grounds “will forever remain inviolate to anthropogenic effects”.

Winter ranges and migratory routes are variously threatened by warming climate, and pressures from agriculture, ranching, reclamation, pollution, residential development, erection of wind turbines (wind farms), and burgeoning human populations. Studies on American Golden-Plover winter range in Argentina (Blanco et al. 1993, Blanco 1998, Blanco et al. 2004) indicate that: birds tend to avoid agricultural areas and concentrate instead on “flooding pampa” lowlands grazed by cattle; any modification of these lands (economic conditions might eventually favor drainage and conversion to cropland) would have serious impacts on this species. Also intertidal areas are often important feeding grounds, and some coastal wintering populations in the region are threatened by urbanization and tourism. Clearly, the American Golden-Plover is less able than Pacific Golden-Plover to coexist with humans during the non-breeding season.

Potentially harmful effects of wind farms greatest for American Golden-Plovers during migrations along continental pathways (Clay et al. 2009). Notably, a major stopover site for this species in Indiana (see Migration: migratory behavior, above) is also the site of a massive wind farm development (Clay et al. 2009, www.BP.com/energymix/wind). Given the adaptive nature of the Pacific Golden-Plover (see Habitat: winter range, above), anthropogenic threats on its wintering grounds are less apparent, though studies across much of the vast region used by this plover are fragmentary and human population is rapidly expanding over most of the winter range. Rising sea levels (with global warming) would damage or eliminate large areas of wintering habitat for shorebirds (Galbraith et al. 2002). This impact is potentially very significant on the winter range of the Pacific Golden-Plover (much of which consists of low-lying land across the insular Pacific) and on intertidal wintering habitat used by American Golden-Plovers in South America.

Effects of pesticide exposure on wintering grounds and along migratory routes remains essentially unknown. Feeding in rice fields may be particularly hazardous (see Blanco et al. 2006a). In the 1970s, a pooled sample of 8 birds collected on the Seward Peninsula (unclear if American or Pacific Golden-Plover or both) contained relatively high levels of DDE and PCBs (Walker 1977). More recently, American Golden-Plovers collected on breeding grounds contained low levels of DDE, dieldrin, heptachlor, and PCBs (n = 5 birds at Rankin Inlet, NU; Court et al. 1990), and DDT, DDE, dieldrin, mirex, PCBs, mercury, cadmium, selenium, and arsenic (n = 8 birds at Churchill; Braune and Noble 2009). No DDT-associated eggshell thinning found in golden-plover eggs (species uncertain) from Alaska (Morrison and Kiff 1979). Many Pacific Golden-Plovers winter on golf courses in Hawaii where they come in contact with potentially hazardous chemicals (Johnson and Johnson 1993c). Strum et al. (2008) measured plasma cholinesterase in healthy American Golden-Plovers as a means to establish baseline values against which to measure possible cholinesterase-inhibiting effects of organophosphate and carbamate pesticides. Subsequent sampling of this species in South America “did not show evidence of exposure” (Strum et al. 2010).

Collisions of Pacific Golden-Plovers with aircraft have occurred at Lihue and Kahului airports in Hawaii, especially during late fall. Studies reveal: that almost all strikes involved inexperienced, newly arrived juveniles attracted to open spaces of runways; that territorial adults wintering on grassy runway/taxiway borders habituate to aircraft and pose negligible safety hazard; that strikes usually occur during landings, seldom on takeoffs; and that there are very few plover strikes relative to volume of air traffic at these facilities (Johnson 1992, Johnson and Johnson 1993a, b, Linnell et al. 1996). Newer, quieter, larger-bodied aircraft are of potential concern as naïve juveniles may be less able to avoid them (Sodhi 2002, Johnson 2003). Allowing grass to grow tall along runways would probably exclude territorial birds, but this is unlikely to reduce plover strikes significantly. Also, taller grass may attract other, more troublesome species. Safety measures best directed at hazing of juveniles during critical fall migration period (see Johnson 2003).

Management

Status listings for the two species in major shorebird conservation plans [U.S. Shorebird Conservation Plan (USSCP, Brown et al. 2001), Canadian Shorebird Conservation Plan (CSCP, Donaldson et al. 2000), U.S. Pacific Island Regional Shorebird Conservation Plan (PIRSCP, Engilis and Naughton 2004), U.S. Fish and Wildlife Service High Priority Shorebirds (HPS, U.S. Fish and Wildlife Service 2004), Alaska Shorebird Conservation Plan (ASCP, Alaska Shorebird Group 2008), U.S. Fish and Wildlife Service Birds of Conservation Concern (BCC, U.S. Fish and Wildlife Service 2008)] have ranged widely over the past decade emphasizing lack of consensus, uncertainty as to population trends, and the need for solid information. Summary of foregoing listings/rankings: American Golden-Plover, species of high concern (USSCP, CSCP, HPS), priority species of high concern (ASCP), species not listed (BCC); Pacific Golden-Plover, species of high concern (USSCP, PIRSCP), moderate concern (CSCP, ASCP, HPS), species not listed (BCC). Of the two species, American Golden-Plover appears to be the most threatened and a conservation plan for this bird (available online at www.whsrn.org) was recently completed by Clay et al. (2009). The plan details strategies, actions, and research needs. No similar plan has been developed for the Pacific Golden-Plover. For both plovers, habitat preservation, population monitoring, basic research, and education programs of international and regional shorebird agencies (e.g., Western Hemisphere Shorebird Reserve Network, Shorebird Research Group of the Americas, Wetlands International, Alaska Shorebird Group) will be of vital importance in the future.