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Data for: Mammalian predators and vegetated nesting habitat drive reduced protected area nesting success of Kentish plovers, Yellow Sea region, China

Cite this dataset

Li, Donglai et al. (2023). Data for: Mammalian predators and vegetated nesting habitat drive reduced protected area nesting success of Kentish plovers, Yellow Sea region, China [Dataset]. Dryad. https://doi.org/10.5061/dryad.6wwpzgn39

Abstract

Protected areas provide essential habitats for wildlife by conserving natural and semi-natural habitats and reducing human disturbance. However, whether breeding birds vulnerable to nest predation can benefit from strict land management in the protected area is unclear. Here, we compare the nesting performance of two groups of a ground-nesting shorebird, the Kentish plover (Charadrius alexandrinus), in the protected area (Liaohekou Natural Reserve, hereinafter PA) and the control non-protected area (Non-PA) around the Liaohekou Natural Reserve, in the north of the Yellow Sea, China, and identify which environmental factors, such as nesting habitat and nest materials, influence the daily nest survival rate (DSR). We found similar nesting habitats in both study areas, dominated by bare land or Suaeda salsa grassland. However, DSR was lower in PA (0.91 ± 0.01) than in Non-PA (0.97 ± 0.01). Kentish plovers nesting in areas with vegetation cover experienced lower DSR than in bare lands in both areas, and nests built with materials of S. salsa sticks had the lowest DSR in the bare land. Data from infrared cameras confirmed relatively higher predator abundances and nest predation rates by nocturnal mammals, such as Eurasian badgers (Meles meles), in PA than in Non-PA, and this pattern was especially evident for plover nests located in S. salsa grassland. Our results suggest that Liaohekou Natural Reserve protected area may not necessarily provide safe nesting sites for Kentish plovers due to the abundance of generalist mammal nest predators. However, the PA includes about 80% of the nests from both locations. This means the contribution of the total number of successful nests continues to be much higher within PA, with the benefit for the species that this brings in terms of conservation. The variation and mechanisms underlying differences in the nest predator communities of PA and non-PA deserve further study.

Methods

All the selected breeding habitats of Kentish plover were systematically searched for nests between May and July each year. When nests with at least one egg were found, a Handheld GPS (Garmin 62) was used to record its location. Each nest was photographed using a digital camera (Nikon J5) to record the nesting environment and the composition of nest materials. Eggs were floated to estimate the incubation stage following the technique by Hays & Lecroy (1971). Nests were inspected 1-2 times per week during the early incubation stage (< 22 days after egg-laying) and at 1–2 days intervals after 22 days of incubation (26 days) (Que et al., 2015). We limited the time observers spent in proximity to each nest to no more than 5 mins to minimize potential disturbances and the chances of nest abandonment. Nest fate was categorized as follows: (A) Failure: nests were considered to have failed when (1) eggs were observed being collected or destroyed by humans; (2) nests were considered predated when there was evidence of predation e.g., camera images, yolks, egg content remaining in/around the nests; (3) were washed away by water or buried by mud due to flooding events and bad weather; (4) were abandoned (i.e., nests in which eggs were still present but were cold for two nest-checking periods. (B) Success: nest fate was considered to be successful when: (1) at least one nestling left the nest, (2) all eggs disappeared within two days of the estimated date of hatching, and did not meet any of the four criteria for ‘failure as mentioned above. (C) Unknown: nest fate was considered unknown when: the above-mentioned failure and success judgment criteria could not determine the fate of the nests. Nests with unknown fate (4.2%, n = 12) were not included in the subsequent statistical analyses ( e.g., nest success rate).

Nesting habitats were recorded as either vegetated or bare land (Fig. 2A, B). All the nests with at least 50% vegetation coverage within a 30 cm radius were classified as vegetated habitats. The vegetation covering the nests was mostly S. salsa (85.4%, n =82), while short reed (Phragmites australis) represented the other 14.6% (n = 14). We estimated nest concealment by assessing visual obstruction by vegetation in five directions (up, N, E, S, and W) (Zero (0) = no vegetation cover in all directions, 5 = shielded in all directions) following Burhans & Thompson (2001). Most plover nests were dominated by one particular suite of substrates shells, stones or plant materials (the latter of which mainly consisted of dead S. salsa stems. We categorized the nests from the digital photographs using these criteria. Nests classified as “others” were mainly composed of mud (Fig. 2C, D, E & F). In addition, for each nest we also recorded the closest distance to the nearest road, water edge, mudflat, coastline, and PA boundary, which were estimated from updated high-resolution satellite images (http://www.sasclouds.com) using Arc GIS (v 10.2). Due to the fact that some plover nests were located outside the PA, we used the negative value to represent the relative distance to the PA boundary. 

The distance matrix between each nest was calculated using R package “geosphere”(version 1.5-14). The nearest neighborhood distance was defined as the shortest distance between conspecific nests during the active period. In addition, an annual aggregation index for each nest relative to the spatial distribution of all Kentish plover nests was calculated using the formula Σ exp (−dij) (with i ≠ j), where dij was the linear distance between nest i and j (Hernández-Brito et al. 2020).

Usage notes

RMark v2.2.7

Funding

Basic Scientific Research Projects of Liaoning Provincial Department of Education, Award: LJKZ0093

National Natural Science Foundation of China, Award: 31672316

Non-profit Foundation of Marine Environment and Ecological Conservation of CNOOC, Award: CF-MEEC/TR/2021-14

National Natural Science Foundation of China, Award: 31911540468