African Black Oystercatcher Monitoring
Since our inception, the Strandloper Project has monitored the African Black Oystercatcher (Heamatopus moquini) population between Wilderness and Brenton on Sea. In 2020, on our second coastal research expedition, we started recording sightings of Oystercatchers. On the 5 expeditions between 2020 and 2024, we have recorded over 2000 oystercatchers, and analysis of our database shows that there are varying population densities along the coastline between Pringle Bay and Cape Recife.
To expand our database and understanding of these endemic species, we are inviting citizen science volunteers to survey and record African Black Oystercatcher sightings on their recreational beach walks.
African Black Oystercatcher Citizen Science Survey
To expand our survey data, Strandloper Project is inviting beachgoers, birders, nature lovers and aspirant environmentalists to assist us in conducting African Black Oystercatchers surveys while walking on the beach.
To collect the data, volunteers will record their sightings of oystercatchers using the Cybertracker app on their smart phone.
Information on how to load and use the app is at the bottom of the page.
Description of Oystercatchers
African Black Oystercatchers are endemic to southern Africa and are found along the coastlines of South Africa and Namibia.
African Black Oystercatchers, Heamatopus moquini, are a species that is endemic to the shoreline of southern Africa, extending from Port Edward on the east coast of South Africa up the west coast of Namibia to the Hoanib River mouth. They forage in the intertidal zone, most active at low tide, targeting Brown Mussels (Perna perna), Mediterranean Mussels (Mytilidae galloprovincialis), Sand Mussels (Donax serra), Limpets, polychaetes and crustaceans. Occasionally they will scavenge washed up Red Bait (Pyura spp)
Living up to 29 years, the onset of first breeding occurs between 3 and 7 years. Breeding is seasonal, with pairs initiating the establishment of breeding territories in October and laying 1 or two eggs between mid-November and early December with an incubation of approximately 30 days.
In the mid to late 1990’s the conservation status of African Black Oystercatchers was near threatened and considered the second most threatened avian species in South Africa, due to their low recruitment rate and susceptibility to human disturbance, particularly during breeding season. It was their susceptibility to human disturbance which motivated the banning of off road vehicles on beaches by the then SA Minister of Environmental Affairs and Tourism on the 21st December 2001. In the Garden Route, within 10 years, an increase of 40% was recorded, in most part attributed to the exclusion of ORV on beaches
Nest
African Black Oystercatchers nests are often a simple scrape in the sand above the high water mark. While their mottled colouration provides some thermal regulation through Brownian motion in the eggs white when not incubated by an adult, they will overheat and die if left exposed to the summer sun for too long.
Oystercatcher Eggs
A clutch of between 1 and 3 eggs are laid between late October and late November and are incubated by both adults. The eggs hatch in late November to mid December.
Intrinsically, African Black Oystercatchers are not defensive of their nests, and will retreat from the nest when approached by beachgoers, only returning when the presence of humans has moved away. If beachgoers remain in close proximity to a nest for an extended period of time, the parents will fly overhead emitting alarm calls. Occasionally a pair will dive bomb people, but that is more the exception than the norm.
This behavior also occurs when human presence is close to chicks.
In the event that you hear adult oystercatchers alarming close to you, identify where the nest is and move more than 50m away so that they can return to incubate their eggs.
Oystercatcher Chicks
Oystercatcher are precocial, following their parents on foraging forays as soon as they hatch. The newly hatched chicks are mottle downy grey black and transition to the adult black plumage at approximately 4 weeks old, though their bill and legs remain black, only becoming orange after 3 months.
When disturbed or threatened, the chicks will immediately drop down and remain totally still until the adults emit a call to signal that the threat has moved on. If they are in the intertidal zone, they are at risk of drowning as they will not move, even when waves wash over them.
If one or both adults are alarming, it is imperative to move off, retreating over 50m so that the adults can lead the chicks to safety.
African Black Oystercatcher Survey
To get a better understanding of the factors that influence the density and distribution of African Black Oystercatchers in the Western and Southern Cape, the Strandloper Project survey this species on their annual coastal research expedition.
Between 2019 and 2024, the research team have hiked 1100Km of coastline between Pringle Bay and Cape Recife and surveyed oystercatchers between Pringle Bay and Blombos and between Wilderness and Cape Recife.
To date Strandloper Project has recorded over 2000 African Black Oystercatchers and determined variations in population density ranging from as low as 2 birds per 2000m to densities of over 11 birds per kilometer.
Factors influencing African Black Oystercatcher Density
Reviewing our data, what stands out is that the type of shoreline has a direct influence on regional densities of oystercatchers, underpinned by target prey species distribution, with sand shores supporting lower diversity and densities of prey species compared to rocky intertidal shelves where territorial ranges vary from 1 breeding pair per 2000m on sandy shores and 200m/breeding pair on flat intertidal shelves.
Within these two types of shorelines, there are noticeable variations in the densities, ranging between 1 pair/2000m and 1 pair/280m on sandy shores and 1 pair/200m and 1 pair/1.25km on rocky shores
On sandy shores, the average density of 1 pair/2000m holds true except one section between the Gamtoos River and Van Stadens River mouths, where 45 observations of 124 oystercatchers indicate the density was an impressive 280m/pair. It would appear that this section of shoreline has a high density of Sand Mussels, as witnessed by telltale ‘butterflied’ shells, to support the population of Oystercatchers along this stretch. Fossil records of predominantly Sand Mussels in middens in the dunes along this sandy shoreline indicate that the high density of this prey species has been historically stable.
Human Impact
Another major influence on the density and distribution of oystercatchers in the surveyed area, is that of human beach activities also play a role. The breeding season of oystercatchers coincides with the summer holiday season of South Africa, with large numbers of holiday makers present during egg incubation and while chicks are dependent on their parents.
Adult oystercatchers displaced from their nests by holiday makers setting up nearby, fishermen, positioned at feeding zones in the intertidal zone and vehicles driving on beaches illegally all have an impact on the nesting success and recruitment of oystercatchers.
Become a Citizen Science Volunteer
Survey Method
- Walk a minimum of 1km along the shoreline. There is no upper limit to the length of your survey hike.
- Using the Cybertracker app, record the number, age demographics, activity and substrate of each oystercatcher sighting.
- Capture each sighting as close to the location of the oystercatchers as possible.
- If they fly ahead of you when you approach, capture the record at the location where they flew from. Do not record them when you approach them again.
- The best time to conduct a survey is at low tide.
What do you need?
- Smart phone, IOS or Android, with GPS
- Install the Cybertracker App on your smart phone.
- Install the Strandloper Project Oystercatcher program for Cybertracker
How to Install Cybertracker on your Smart phone
- Visit your Play or App store and search for CyberTracker.
- Download the Cybertracker App
How to Install the Strandloper Project Oystercatcher survey program.
- Make sure that your phone is connected to the internet.
- Open the Cybertracker App.
- Select permissions required for Cybertracker App
- Click on Scan tab at the bottom of the screen
- Aim the camera at the QR code on the right hand side.
- The Strandloper Project oystercatcher app will load and open on the title page.
How to Record Sightings
Watch the video on YouTube on how to capture oystercatcher sightings using Cybertracker. Watch the video.
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