Black Oystercatcher Nest and Diet Data from Kachemak Bay, Katmai National Park and Preserve, Kenai Fjords National Park, and Prince William Sound

Black Oystercatcher transect and nest monitoring and prey sampling data are recorded on hard copy data sheets while in the field. There are three components of sampling related to Black Oystercatchers: 1) estimation of breeding pair density and nest occupancy through oystercatcher-specific surveys, 2) egg float stages used to estimate hatch date of nests, and 3) estimation of species composition and size distributions of prey provisioned to chicks. Detailed survey methods for estimation of nest occupancy and diet can be found in the Black Oystercatcher breeding territory occupancy and chick diet SOP (Bodkin 2001b). Black Oystercatcher nest density, nest occupancy, and prey data were collected along transects centered on the rocky intertidal monitoring sites. Rocky sites were initially chosen based on their slope (not vertical), substrate, and extent (at least 100m continuous rocky habitat). All sites were also relatively protected from high wave exposure and were associated with freshwater sources, although to varying degrees. Each site contains one survey transect. Nest sites were located by surveying the shoreline in a small boat. All accessible nest sites were visited to determine the number of chicks and/or eggs present, float eggs, and collect all prey items at the nest. Each survey transect was centered on the rocky sampling site location described in the "Monitoring Site Locations" data release: https://doi.org/10.5066/F78S4N3R (Coletti et al. 2017). Beginning, in 2018, some transects were shortened to eliminate portions with unsuitable nesting habitat. These parts of the transects that were eliminated never contained a nesting pair. The new transect lengths vary by site and are no longer precisely centered on the rocky sampling site. The new transect lengths, in kilometers, are: Cohen (KEP_B04_RE_03): 27.14, Outside (KEP_B04_RE_04): 29.34, Port Graham (KEP_B04_RE_05): 27, Elephant (KBY_B13_RI_06): 13.03, Aialik (KEP_B05_RI_01): 30.44, Nuka Bay (KEP_B05_RI_03): 4.35, Nuka Pass (KEP_B05_RI_04): 15.6, Harris (KEP_B05_RI_05): 16, Iktua (PWS_B08_RI_02): 14.2, Whale (PWS_B08_RI_03): 8, Johnson (PWS_B08_RI_04): 16.2, Herring (PWS_B08_RI_05): 17.4, Kukak (AKP_B10_RI_01): 6.33, Kaflia (AKP_B10_RI_02): 7.47, Kinak (AKP_B10_RI_03): 10.29, Amalik (AKP_B10_RI_04): 9.64, Takli (AKP_B10_RI_05): 12.54. Eggs were floated in a transparent container of freshwater to determine the float stage to estimate hatch date. Each egg was assigned to one of five float stages based on the location of the egg in the water column (i.e., sinking, at surface, or breaking surface) and the angle between the horizontal plane of the water and the longitudinal axis of the egg.