Project Abstract
The Mountain Plover (Charadrius montanus) is a loosely colonial (Graul 1975)
upland shorebird that breeds across the xeric tablelands of the western Great Plains
and shortgrass prairie ecoregion of North America (Knopf and Wunder 2006). This
is a species of conservation concern throughout its range because of apparent range-wide
population declines (Knopf and Wunder 2006). Bruner et al. (1904) described the
species as “not uncommon in extreme western Nebraska” at the turn of the 20th
Century and noted the species had been observed in Cheyenne, Dawes, and Sioux Counties.
As late as the new millennium, Sharpe et al. (2001) described the species as a rare,
regular breeder limited to southwestern Kimball County.
In 2002, the NPP made a concerted effort to gain access to private lands in the
southwestern panhandle before initiating systematic research and monitoring activities
focused on Mountain Plover ecology. We reviewed data collected from our monitoring
activities to reassess the status of Mountain Plover in Nebraska including 1) estimated
arrival dates of spring migrants and departure dates of fall migrants, 2) nesting
chronology and time intervals of peak nesting activity, and 3) a general distribution
of breeding Mountain Plovers in the southwest panhandle.
“Mountain Plover in an agricultural field in southwestern Nebraska”
“Recently hatched Mountain Plover chicks in an agricultural field nest in Nebraska”
Preliminary surveys detected Mountain Plovers across the study area in early spring.
In 2006 and 2007 these surveys were initiated on 3 April and 20 March, respectively,
in order to better approximate the first day Mountain Plovers arrive in Nebraska.
These surveys were also conducted opportunistically at similar areas in late August
and early September in 2006 and 2007 to estimate the last day that Mountain Plovers
were observed across the study area before fall migration.
NPP implemented a nest marking program in Nebraska from late April through the end
of June in all field seasons beginning in 2004. Working in conjunction with local
producers, nests were located in agricultural fields by driving parallel transects
with ATVs in fallow and stubble strips till adult birds were flushed. When we located
a nest, we floated the eggs to estimate nest age according to Dinsmore et al. (2002).
We subsequently revisited nests twice a week to determine their fate (e.g. – successful,
predated, abandoned, etc.). We assumed a 29-day incubation period (Knopf and Wunder
2006) to estimate when nests were laid.
Roadside transect surveys and the patch surveys began in mid-April of all years,
and continued through the end of May or first week in June. In 2003, we conducted
roadside surveys to determine Mountain Plover occupancy throughout the 17 counties
of extreme western Nebraska; Sioux, Dawes, Sheridan, Box Butte, Scotts Bluff, Banner,
Morrill, Kimball, Cheyenne, Deuel, Garden, Keith, Perkins, Chase, Dundy, Hayes,
and Lincoln Counties. Patch surveys were conducted during the 2004-2007 field seasons
at areas where plovers were encountered during the 2003 surveys.
The earliest observations of Mountain Plovers in Kimball County were 2 adults on
5 April 2002, 4 adults on 18 March 2003, 5 adults on 8 April 2004, 4 adults on 3
April of 2006, and multiple groups of three plovers on 24 March 2007. Our latest
observations of Mountain Plover in Nebraska for the 2002, 2003, and 2004 field seasons
were 1 August (10 fledglings), 15 August (1 adult), and 16 July (5 adult, 4 fledglings),
respectively. However, increased survey effort in the fall of 2006 and 2007 resulted
in the observation of a flock of 28 plovers (mostly juveniles) on land adjacent
to an area with relatively high nest densities on 31 August 2006. Additionally,
on 3 September 2007 we observed 78 Mountain Plover (both adults and juveniles) on
the adjoining land to the south of where the 2006 group was observed.
While few Mountain Plover nests had ever been located in Nebraska (see Sharpe et
al. 2001 for a listing of all events), our monitoring efforts yielded a total of
278 nests (272 on agricultural fields and 6 on native rangelands) over the duration
of this study. The majority of Mountain Plover nests in Nebraska were laid during
the first two weeks of May. Using these nests, we were able to back estimate the
onset of Mountain Plovers nesting to late April of all years. We estimated the earliest
nests were laid on 26 April 2006 and 28 April 2007, based on hatching dates and
a 29 day incubation period.
We observed Mountain Plovers incubating eggs into the middle of July, which is when
it was previously believed that plovers were migrating south (Sharpe et al. 2001).
While the possibility exists that the birds observed in late August and early September
of 2006 and 2007 were migrants from areas farther north, a number of our marked
nests in Nebraska during the 2006 and 2007 field seasons did not hatch until mid-July.
This information coupled with the 34-36 day chick-fledgling period (Knopf and Wunder
2006), suggest that the groups observed in late August and September could have
been locally-reared juveniles that had not yet migrated.
Figure 1. Estimated date that Mountain Plover nests were laid based on a 29-day
incubation period. For nests hatched between revisits, 29-day incubation is applied
from the middle of relevant nest visits. Nests were located in Kimball County, Nebraska
during nest marking for the 2005-2007 field seasons.
Mountain Plovers were observed in Banner, Cheyenne, and Kimball Counties during
patch surveys. Approximately 83% of our occupied survey patches were located south
of I-80 in Kimball County. Plover nests were also located in the three aforementioned
counties, but most nesting by plovers was concentrated in southern Kimball County.
Based on our data, we estimate the current distribution of plovers in Nebraska (Figure
3) to include the southwestern portion of Cheyenne County (southwest of Sidney and
south of I-80), all of Kimball County except the area north of I-80 and east of
Highway 71, and the very southern portion of Banner County (west of Highway 71).
While Mountain Plovers were located across this entire range, we found multiple
core nesting areas (all within Kimball County) where breeding densities were much
higher.
Figure 2. Rough distribution of breeding Mountain Plover (shaded area) observed
in the southwest panhandle of Nebraska during the 2002 through 2007 field seasons.
Compared with historically documented sightings, our results indicate that Mountain
Plovers are more numerous in Nebraska than previously believed. Our results suggest
a spring migration chronology similar to that suggested in Colorado (Graul 1975),
with Mountain Plover arriving in Nebraska in mid- to late March, which is earlier
than previously documented in Nebraska (Sharpe et al. 2001). Our data also suggest
that juveniles may reside within the state as late as early September, which is
significantly longer than previously documented (Sharpe et al. 2001). If true, this
suggests that Mountain Plovers are present on the breeding grounds in Nebraska for
approximately 5 months in any given year. Our assessment of Mountain Plovers in
Nebraska, using the same terminology of Sharpe et al. (2001), suggests that their
status should be revised from a rare, regular breeder to an uncommon to fairly common,
regular breeder with a localized distribution within the state.
Literature Cited
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