Endangered and Threatened Species of the Platte River (2005) / Chapter Skim
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6 Piping Plover and Interior Least Tern
6 Piping Plover and Interior Least Tern
Pages 186-224
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From page 186... ...
As their habitat has been lost, populations of piping plovers and interior least terns have declined dramatically along the central Platte River. The following chapter explores three specific questions posed to the committee: Do the present habitat conditions on the Platte River affect the likelihood of survival and recovery of the piping plover?
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From page 187... ...
population was listed, Platte River nesting records have been consistently collected and maintained. The general method used to obtain estimates of breeding pairs throughout the piping plover range is to walk toward potential nest habitat or approach it by boat (Plissner and Haig 2000)
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From page 188... ...
At the end of each season, data on pair estimates and nesting success are sent to NGPC, where the Nebraska piping plover database is maintained. Since records were first recorded for piping plovers, the methods have become more formalized, particularly after the methods section of the Cooperative Agreement Tern and Plover Monitoring Protocol was prepared.
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From page 189... ...
Current estimates indicate that nesting pairs of piping plovers in Nebraska make up 10-12% of the NGP population, and about 9% of Nebraska's breeding piping plovers nest on the central Platte River (Dinan, NGPC, pers. comm., May-September 2003)
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From page 190... ...
reported a 61% decrease in piping plovers nesting on the central Platte River from 1991 to 2001, so piping plovers appear to have declined over the last decade at regional, state, and local levels. Declines at all levels are attributed primarily to human activities, including direct and inadvertent harassment of birds and nests by people, domesticated animals, and vehicles; destruction of shoreline habitat as a consequence of development projects; increased predation due to human presence in less-visited beach areas; and water-level regulation policies that result in changes in nesting habitat (Haig and Elliott-Smith, in press; Haig 1992)
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From page 191... ...
Without human observers present to look for banded birds, it is not possible to infer where the surviving banded birds eventually nested. Lingle did, however, obtain several dispersal records worth noting: seven birds were observed at other nest locations in the Platte River Valley, including an adult banded near Kearney that nested 155 mi downstream 2 years after banding and a banded bird captured at Lake McConaughy, 300 mi from its banding site on the lower Platte River.
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From page 192... ...
. Piping plovers typically arrive at the Platte River in middle to late April and depart by late August.
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From page 193... ...
After young birds fledge, they continue to feed and mature along the Platte River until they begin autumn migration in August. Influence of Current Central Platte Conditions on Survival of Piping Plovers on Platte River Plovers, like all species, have specific requirements for survival.
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From page 194... ...
The effort was an important contribution to understanding of the piping plover habitat requirements along the central Platte River. Using an airboat, Ziewitz's research team traveled the reach of the Platte River from Lexington to its confluence with the Missouri River in the middle of June.
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From page 195... ...
Chick productivity at river sites along the central Platte declined to about 1.3 chicks per pair in 1997 and 1998; since 1999, there has been no successful reproduction. In addition to riverine habitat, piping plovers nest in commercial sandpits on the central Platte River.
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From page 196... ...
(early stage site initiation) at Habitat nest Habitat sandbar width area Elevation a nest nest stage nest or 6-1 at elevation at 400-cfs June, at (at habitat sandbar Plover Channel Sandbar June, Mean 400-cfs June, Maximal above (early initiation)
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From page 197... ...
197 1993 1993 1996 elevation Ryan 1993 1993 yield and to Armbruster Armbruster Kirsch Kirsch and and and and adjusted Corn Corn Nordstrom Sidle Sidle were data original datum, cfs)
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From page 198... ...
The presence of the habitat components required for survival influences whether piping plovers are able to nest, hatch eggs, and raise their offspring to fledging. According to USFWS and NGPC biologists (Erika Wilson and John Dinan)
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From page 199... ...
failures at sandpits. In summary, current conditions in the central Platte River appear to be compromising the continued existence -- that is, the survival -- of the NGP population of the piping plover.
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From page 200... ...
reported a 1987-1998 average of 84 pairs of piping plovers breeding on the Platte River including birds nesting in sandpits along the river. If Lake McConaughy birds are included, the average is 119 pairs.
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From page 201... ...
Three PVAs have been published for the NGP population of piping plovers (Ryan et al. 1993; Plissner and Haig 2000; Larson et al.
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From page 202... ...
The analysis was based on a number of assumptions about the spatial structure of piping plovers in the NGP population; before the contribution of birds from the central Platte or the Platte River system can be accurately evaluated, movements of birds among habitat areas and their uses of those areas must be better understood. Although insufficient data are available to construct a PVA for piping plovers on the Platte River that has a high level of resolution and predictive power, the committee used the VORTEX model 9.3 (Lacy et al.
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From page 203... ...
% nests 49.68 79.9 51.75 58 58 72.4 failing Source: Reed 2003. TABLE 6-3 Migration Rates Among Piping Plover Populations Manitoba and Great Lake of the Northern Platte and Lakes Woods Prairie Loup Niobrara Colorado Great Lakes -- 0.001 0 0 0 0 Manitoba and 0.001 -- 0.01 0 0 0 Lake of the Woods Northern 0 0.01 -- 0.01 0.01 0 Prairie Platte and 0 0 0.01 -- 0.02 0.005 Loup Niobrara 0 0 0.01 0.02 -- 0.005 Colorado 0 0 0 0.005 0.005 - Source: Reed 2003.
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From page 204... ...
2002) for the Great Lakes and NGP populations of piping plovers.
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From page 205... ...
0.145 -- 0.232 0.078 Source: Reed 2003. Evaluation of Science Supporting Piping Plover Critical Habitat Designation Critical habitat for the NGP breeding population of the piping plover was designated in 2002, including 19 critical habitat units totaling 183,422 acres (74,228 ha)
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From page 206... ...
For the NGP population of piping plovers, the PCEs of critical habitat are the essential habitat characteristics for the biological needs of courtship, nesting, sheltering, brood-rearing, foraging, roosting, intraspecific communication, and migration (Fed. Regist.
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From page 207... ...
. In addition to the general systematic properties of the central and lower Platte River, USFWS investigated four more-specific characteristics required for designation of critical habitat.
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From page 208... ...
USFWS began its designation process by using recovery plans (USFWS 1988; USFWS unpublished material, December 23, 1994) to identify the specific recovery needs of NGP piping plovers (including birds nesting on the central Platte River)
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From page 209... ...
. In this region, interior least terns often nest near piping plovers and for this reason are thought to have similar habitat requirements.
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From page 210... ...
Breeding terns in Nebraska typically co-occur with piping plovers on sandbars, on reservoir shorelines, in commercial sand mines, and at other artificially created sites along three major rivers (Figures 6-1, 6-2, and 6-3)
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From page 211... ...
Study methods for interior least terns were similar to those described above for piping plovers. Using aerial videography, Ziewitz et al.
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From page 212... ...
212 1990 1984 1992 1992 1992 1992 1988 1988 Kelly al.
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From page 213... ...
213 1990 elevation 1993 1993 1993 yield Renken Kirsch Kirsch Kirsch to 1991 and and and and Smith Sidle Wilson Sidle Sidle adjusted were data original datum, cfs)
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From page 214... ...
. The study showed that more terns nested on the lower Platte River than on the central Platte and that birds nested on river segments that were wider and had larger areas of unvegetated or sparsely vegetated sandbars than on vacant sites.
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From page 215... ...
reviewed the status of the interior population and stated that "methods, level of effort, and degree of coordination that biologists use on the upper Missouri, the Platte, and lower Mississippi rivers are needed throughout the interior breeding range"; that supports the idea that data used to recommend conservation and management strategies for interior least terns on the Platte River have been drawn from appropriate scientific approaches. Because piping plovers and interior least terns typically co-occur on the Platte River, the species are surveyed at the same time, and similar methods are used, as described earlier in this chapter.
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From page 216... ...
, central Platte (74) , and lower Platte (187)
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From page 217... ...
The authors' recognition that the central Platte River birds contribute substantially to the joint persistence of the populations is correct in the context of the model, but the model makes implicit assumptions about each of the local populations, for example, that Platte River birds are self-replacing (the population is not maintained in part by immigration) , which probably is not valid.
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From page 218... ...
The committee's conclusions about effects on survival of interior least terns and piping plovers were similar. As in the case of the PVA for the piping plover, the committee used available data to ask several basic questions about the persistence of the Platte River interior least tern population.
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From page 219... ...
2003) ; environmental variance for reproduction and survival, 20% of the parameter value; no inbreeding depression; no catastrophic environmental events; no change in carrying capacity over time; and no cost to dispersal.
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From page 220... ...
The current recovery plan has a goal of 920 adults in the Platte River and Loup River combined. A PVA assuming a completely isolated population of this size was run with the base-model parameters, first in a version with immigration and then in a version of the model that assumed increased reproductive success.
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From page 221... ...
221 c of Time Platte Rate Mean 107 103 95 100 107 123 128 (30%)
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From page 222... ...
The same pattern was found by Plissner and Haig (2000) for piping plovers.
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From page 223... ...
The decline in the river's plover population has been coincidental with the loss of its preferred habitat, especially in the central Platte River, where suppressed variability in flow has led to reductions in sandbars and beaches and indirectly to increased woodland and reduced open sandy areas. The piping plover population along the Platte River has consistently declined since 1996, and improvement in its numbers is likely to be closely tied to habitat conditions on the river that respond to hydrological adjustments.
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From page 224... ...
Platte River terns, for example, appear to range widely (up to at least 170 mi away from the river) , so understanding of the Platte population cannot focus solely on the river.
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