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Many long-distance migrating shorebird (i.e., sandpipers, plovers, flamingos, oystercatchers) populations are declining. Although regular shorebird monitoring programs exist worldwide, most estimates of shorebird population trends and sizes are poor or nonexistent. We built a state-space model to estimate shorebird population trends. Compared with more commonly used methods of trend estimation, state-space models are more mechanistic, allow for the separation of observation and state process, and can easily accommodate multivariate time series and nonlinear trends.

Summary of the 2015 Summer Wetland Bird Counts in Namibia.

An aerial survey specifically aimed at mountain zebra (Equus zebra hartmannae) was carried out by the survey unit of the Ministry of Environment and Tourism from 19 to 24 June 2013. The survey covered the Naukluft Mountains in the Namib-Naukluft Park and a large area of the Khomas Hochland west of Windhoek, between the Swakop River in the north and the Naukluft Mountains in the south (Figure 1). The survey was carried out using a Bell Jet Ranger 206 helicopter (V5-HIR) with a crew of four using standard aerial survey methodology.

The following is a summary of waterbird count data for selected species in Namibia, covering the period 1977 to December 2008.

Conducting aerial surveys is one of the core functions of the Ministry of Environment and Tourism. The surveys are essential management tools, allowing for informed decision making. Aerial surveys have been conducted in Etosha National Park since 1968. Apart from a series of elephant surveys, these surveys were strictly speaking not comparable as they were undertaken at irregular intervals with different sampling intensities and area cover. The first comprehensive multi-species sample count was conducted in 1995, and repeated in 1998, 2000, 2002, 2004, 2005 and 2010.

This is the last article in a series describing the results of regular wetland bird counts in Namibia. This paper looks at eight coastal sites, including two of Namibia's four Ramsar sites i.e. Sandwich Harbour and Walvis Bay. Unfortunately data for Namibia's other coastal Ramsar site, the Orange River Mouth, is incomplete and hence it has not been included in this analysis. (Larger scale replications of the graphs in this article are attached to the end of this edition).

The survey took two hours 54 minutes, which translates into a search rate of 1.6 km/min. The flight path was recorded on the GPS tracklog and is shown in Figure 2 (deviations from the transects are where rhino, elephant or large herds of animals were encountered). A total of 253 sightings were recorded during this time (Figure 3) which comprised 1539 animals of seventeen species (Table 1). Kaross game camp is 144 km² in size so the density of animals calculates to 10.7 animals/km². The distribution and herd size for selected species is shown in Figure 4 to Figure 11.