Waterbird Counts at Sabaki River Mouth and Mida Creek

Study Extent

Sabaki River Mouth (IBA: http://datazone.birdlife.org/site/factsheet/6409). Sabaki River Mouth is where the Athi-Galana-Sabaki river system flows into the Indian Ocean some 5 km north of Malindi. Due to the combined action of ocean currents and freshwater flow from the highlands bringing high levels of silt, a diverse array of habitats have been formed. These include open an sandy beach, sandbanks, mudflats, salt marshes, vegetated and bare sand dunes, seasonal and permanent fresh water pools, mangroves, grassland and coastal scrub. Since the mid-1970s a high level of silt deposition has taken place that has extended the river mouth into the ocean and created the wide, open mud and sand flats which are the key attraction for large numbers of waders. Until c. 2000, there was only some degraded patches of mangrove forest slightly upstream. With the siltation, however, conditions have become ideal for mangroves, and an area of over 12 ha of mangrove forest has grown on the northern banks of the river mouth. Seasonal wetlands form during seasons of good rain on the extension of low sand dunes between the beach and the old, high sand dunes and provide breeding habitat for some birds such as Black-winged Stilts. The sandflats and beach are regularly used as a roost for large numbers of gulls and terns which forage out at sea and come to the relative safety of the river mouth to rest. A series of high (up to c. 25 m) wind-blown sand dunes extend about 5 km north and 3 km south of the river. These dunes form an important aquifer and as a result among the dunes are pools and wells of fresh water filtered by the sand and separate from the ocean. "Sabaki" is the name of the final few kilometres of the river that starts in the Ngong Hills west of Nairobi as the Athi River and is known as the Galana River through Ukambani and Tsavo East National Park. Mida Creek (IBA: http://datazone.birdlife.org/site/factsheet/6406). Mida creek is a biologically important and complex tidal marine multi-habitat ecosystem supporting the adjacent local communities by providing foods, building materials and tourism revenues (Weru et al., 2000). The total intertidal area of this marine inlet is approximately 580 ha.: there is minimal freshwater inflow. The majority of the Creek is fringed with a diverse assemblage of mangrove species including Ceriops tagal, Rhizophora rnucronata, Bruguiera gyrnnorrhiza, Avicennia marina, Sonneratia alba and Xylocarpus benadirensis. The site is disturbed by artisanal fishermen, both for fishing and bait-collecting, and by groups of tourists brought into the creek by boat. Disturbance levels are not, however, high enough to have a major detectable influence on the foraging behaviour of waders (Hockey et al. 1996). The major problems in the creek will be the negative knock-on effects within the ecosystem of over-fishing and exploitation of the marine environment and mangrove forests. Mangrove roots are frequently cut and mud dug up in order to reach fishing bait which clearly destabilises the mangroves and threatens their survival (Jackson, The Birds of Mida Creek). Mida Creek is an important passage and non-breeding area for Palaearctic migrant waders, with counts of over 8,000 waders. The populations of Greater and Lesser Sand plover and Crab-plovers here are internationally important. The creek is a significant feeding area for Dimorphic Egrets, Lesser Crested and a resident though non-breeding population of Greater Flamingo. Other common migrant shorebirds here include Sanderling, Curlew Sandpiper, Little Stint, Terek Sandpiper, Whimbrel, Grey Plover, and Greenshank (Jackson, The Birds of Mida Creek).

Sampling

Counts are carried out every month on a date and time with ideal tides (low tide at Sabaki and a neap high of 2.3 - 2.5m at Mida Creek). The team is composed of a staff member from A Rocha Kenya Science Department, a scribe and usually several volunteers. At Sabaki, the same route is follow on foot along the river bank to the river mouth while in Mida, the counts are performed from a stationary point. Binoculars, telescopes and tally counters are used. The scribe writes in a notebook, listing the species with all the counts announced during the survey and, at the end, he/she tallies the counts and write down metadata (start/end times, area covered, effect of weather on the count, disturbance of bird observed). A copy of the instructions(https://a-rocha-kenya.github.io/Waterbird-counts-Sabaki-Mida/data/Notebook_Instruction.pdf) is available. After the count, the staff member enters the count data in an excel spreadsheet, checking the count totals and assigning a count precision.

Quality Control

A rapid quality control has been carried on this dataset but errors are likely to still be present in the dataset. Contact us in case of doubt.

Method steps

1. The conversion to the GBIF standard is performed with a Rmarkdown script (https://a-rocha-kenya.github.io/Waterbird-counts-Sabaki-Mida/scripts/generate_gbif_files).

The Ramsar Convention on Wetlands defines waterbirds as any "species of bird that are ecologically dependent on wetlands". This term is further refined in the second edition of Waterfowl Population Estimates (Rose & Scott, 1997), as being all species of the families Gaviidae, Podicipedidae, Pelecanidae, Phalacrocoracidae, Anhingidae, Ardeidae, Balaenicipitidae, Scopidae, Ciconiidae, Threskiornithidae, Phoenicopteridae, Anhimidae, Anatidae, Pedionomidae, Gruidae, Aramidae, Rallidae, Heliornithidae, Eurypygidae, Jacanidae, Rostratulidae, Dromadidae, Haematopodidae, Ibidorhynchidae, Recurvirostridae, Burhinidae, Glareolidae, Charadriidae, Scolopacidae, Thinocoridae, Laridae, Sternidae and Rynchopidae. Taxa are recorded at the species level with the exception of the Heuglin's Gull (Larus fuscus heuglini) and Baltic Gull (Larus fuscus fuscus). Whenever a bird could not be safely identified at the specie level, the identification was done as slash (e.g. Lesser/Greater Sand Plover), genus, family, order or even as Aves sp.. Our dataset contains 107 species recorded and 6 at other taxon levels (subspecies, family, slash etc.) belonging to 22 families. The taxonID used is the species code from the eBird/Clements Checklist of Birds of the World: v2019 (https://www.birds.cornell.edu/clementschecklist/download/).

1. Scolopacidae
   common name: Sandpipers and Allies rank: family
2. Laridae
   common name: Gulls, Terns and Skimmers rank: family
3. Charadriidae
   common name: Plovers and Lapwings rank: family
4. Phoenicopteridae
   common name: Flamingos rank: family
5. Dromadidae
   common name: Crab-plover rank: family
6. Anatidae
   common name: Ducks and Geese rank: family
7. Glareolidae
   common name: Coursers and Pratincoles rank: family
8. Accipitridae
   common name: Hawks, Vultures, Buzzards, Eagles and Allies rank: family
9. Threskiornithidae
   common name: Ibises and Spoonbills rank: family
10. Ardeidae
    common name: Herons, Egrets and Bitterns rank: family
11. Ciconiidae
    common name: Storks rank: family
12. Pelecanidae
    common name: Pelicans rank: family
13. Recurvirostridae
    common name: Stilts and Avocets rank: family
14. Haematopodidae
    common name: Oystercatchers rank: family
15. Alcedinidae
    common name: Kingfishers rank: family
16. Burhinidae
    common name: Thick-knees rank: family
17. Phalacrocoracidae
    common name: Cormorants rank: family
18. Pandionidae
    common name: Ospreys rank: family
19. Rostratulidae
    common name: Painted-snipes rank: family
20. Balaenicipitidae
    common name: Shoebill rank: family
21. Jacanidae
    common name: Jacanas rank: family
22. Rallidae
    common name: Rails, Crakes and Gallinules rank: family

Located on the coast of Kenya, Sabaki River Mouth and Mida Creek represent key hotspots for waterbirds, especially for wintering and migrating waders. See Sampling Methods for more information.