PRRIP 2008-2009 Interior Least Tern and Piping Plover Monitoring and Research Report

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NEST AND CHICK MONITORING METHODS. We monitored nests located during river or sandpit- island surveys and continued to locate nests throughout the nesting period. We attempted to observe nests and chicks every 3 days until the nest failed or chicks fledged. We made observations from a distance in an attempt not to disturb nesting birds; most often, nests were found by observing adult birds sitting on nests incubating eggs. We recorded date, temperature, observation start and stop times, and the number of interior least tern and piping plover active nests, broods, chicks, and fledglings present during each 3 -day site visit. We also counted the number of eggs present during the initial observation of each nest and estimated the date of nest - initiation. When chicks or fledglings were observed, we estimated the date of hatching or fledging (sustained flight) based on current and previous chick observations. After interior least terns and piping plovers left the colony area, we recorded habitat characteristics at nesting sites including: % vegetative cover, vegetative height, and stem counts within 1 m2 and 5 m2 of the nest; nest elevation; and distance to water. We were granted access to two sandpits owned by Broadfoot Sand and Gravel in the Kearney area ( Broadfoot Newark and Broadfoot Kearney South) to conduct the 3 monthly surveys to count adult birds and document nesting, though access was not granted to monitor nests every three days. We used Program MARK (Version 5. 1) to calculate daily and incubation - period nest survival rates. We included nests located at sandpit and riverine sites that were monitored by personnel from CNPPID, CPNRD, Headwaters Corporation, NPPD, and USFWS -GI during 2008 and 2009 to determine survival rates. We included observations of nests made by personnel from NPWRC in the 2009 analyses. Nest success was defined as any nest that hatched ? 1 chick. As the exact date of nest initiation was unknown on many occasions, we considered the incubation period for interior least terns and piping plovers to be 21 and 28 days, respectively, from when we first observed the nests. When the fate of a nest was unknown, we assign a failed status to the nest if the date of determination was <21 days (interior least tern) or <28 days (piping plover) after the date nest was first observed. For example, if a site with no nests present was surveyed on 8 May; surveyed again on 15 May when a piping plover nest was first observed; was monitored again on 18 and 21 May and we found the nest to be active and intact; but on 24 May we observed no eggs in or adults on the nest, we assigned a "failed" status to the nest as the nest likely did not hatch. If, however, this nest, with an unknown fate, was known to be active on 10 June (26 days after initial observation) and was last observed on 14 June (30 days after initial observation), we censored the nest at 26 days and assigned a "success" status to the nest. Our assumption was that, on average, we discarded survived and failed intervals in the same proportion that they existed in the data. Nests only observed to be active on 1 site visit were .discarded from analyses. We also used Program MARK to calculate daily and brooding - period survival rates. We included broods monitored at sandpits and riverine sites during 2008 and 2009 to determine survival rates. As the exact date of nest hatching was occasionally unknown, we considered the brooding period for interior least terns and piping plovers to be 15 days from the date we first observed nestlings. A successful brood was defined as any brood with >1 chick that survived 15 days after the initial observation of nestling chicks. Similar to nest survival methods, when the fate of a brood was unknown, we assign a failed status to a brood if the date of fate determination was <15 days after we first observed nestlings and a success status to a brood when the date of fate determination was >15 after nestlings were first observed. Broods only observed to be active on 1 site visit were discarded from analyses. PRRIP 2008 -2009 Tern /Plover Report Page 18 of 42