Our November 2024 – March 2024 oystercatcher breeding season is now over. The breeding pairs on the various sections of the beaches were carefully monitored by:
- Wendy and Mark Lucas: on Silversands beach
- Lenore and Duncan Watermeyer: between Main Beach swimming area and the Dawid River outlet,
- Myrna and Colin Cook: between Die Eiland in Stony Point and the rocks west of the Main Beach swimming area.
As always, the Christmas – New Year holiday season has been a challenging time for our oystercatchers, with lots of human and dog activity on the beach at the height of their breeding season. To assist our breeding pairs, we each placed signs at strategic locations on the beaches and marked the nesting sites. With some exceptions, most dog owners obliged by keeping their dogs on a leash when on the beach.
Photo: Colin Chester
In our section of coast, there were nine pairs, but only seven pairs made any breeding attempts. We do not know why the other two pairs made no attempts. Does anyone have any ideas as to why the birds would pair up for the season but then do nothing?
One of our pairs had two unsuccessful breeding attempts. Usually, the eggs are incubated for 28 to 30 days. On their first attempt, they incubated their egg for 63 days before finally abandoning it, and on their second attempt, they incubated their egg for 41 days before the equinox spring tide washed it away. We do not know why neither egg was viable, and why they would persist with the incubation for as long as they did.
There were:
- 11 breeding attempts,
- 20 eggs laid,
- 8 eggs hatched, and
- 3 chicks fledged.
These numbers compare with the numbers from previous years:
|
Breeding season |
19-20 |
20-21 |
21-22 |
22-23 |
23-24 |
24-25 |
|
Breeding pairs |
5 |
7 |
7 |
8 |
8 |
7 |
|
Breeding attempts |
11 |
9 |
14 |
12 |
14 |
11 |
|
Eggs laid |
23 |
18 |
24 |
20 |
25 |
20 |
|
Eggs hatched |
7 |
9 |
9 |
6 |
4 |
8 |
|
Chicks fledged |
4 |
7 |
4 |
5 |
1 |
3 |
Just over one third of the eggs that were laid survived to hatch, and just under one-half of the chicks hatched survived to fledge. As we understand, for the population to remain stable each breeding pair should successfully fledge one chick every three years. If more than this, the population will increase; and if less than this, the population will decrease. This year’s tally of three fledged chicks from nine pairs is on the mark for a stable population.
We have come to realise that being an oystercatcher egg and an oystercatcher chick is a hazardous business, and being an oystercatcher parent is hard work. To successfully raise and fledge a chick is a praiseworthy achievement!
Myrna and Colin Cook, Betty’s Bay Oystercatcher Monitors
Photo from 12 December: Some of the first casualties of this breeding season. These eggs were 20 days old and were due to hatch before Christmas. Myrna Cook
Between Main Beach swimming area and the Dawidskraal River
Here are the statistics for the breeding season from November until April 2025:
- 20 breeding attempts
- 32 eggs lost
- 3 chicks lost
- 4 chicks fledged
The above is relevant to the area monitored which stretches from Main Beach to the Harold Porter River outflow, which includes Dawidskraal and the Bird Sanctuary. The loss of 32 eggs and 3 chick fatalities is disappointing.
The causes are relatively unknown. I can only assume that most of the eggs were lost due to natural predation by Kelp gulls, genets, ravens, mongoose or even otters. Without camera traps it is difficult to ascertain the exact causes.
Due to the high tide, four eggs were lost at Bass River and Dawidskraal area. There is the human interference factor, especially dogs off leash, together with a lot of fishing activity. Fishing near the nesting and feeding areas disturbs the birds which causes them to move off their nests. Eggs or chicks die in the heat of the sun if the nest is abandoned for too long. As Oystercatchers feed at low tide, chicks may perish from starvation if they are prevented from foraging on the rocks. Unfortunately, there is a lot of human disturbance on the rocks, especially during low tide. For example, fishing, people taking “bait” or mussels from the rocks. In my opinion, our Marine Protected Area should be a “no-take zone”. We should be protecting our valuable marine environment and its resources for future generations.
Possible solutions:
- To continue creating awareness with our signage to indicate the nesting areas
- Marking of nests to prevent human disturbances
- To continue providing education, especially for our visitors and fishermen
- To have clearly defined “no go areas” for pedestrians and dogs e.g. the sandy stretch at the Bird Sanctuary which is a prominent breeding section. The Bass river area was an unsuccessful breeding area this season, possibly due to too much human activity.
- Ongoing discussions need to be held with the Local Authorities, Overstrand Municipality and Cape Nature, to ensure that there is adequate law enforcement on the beaches during the holiday season as the number of visitors to Betty’s Bay has increased exponentially.
Oystercatchers are mainly territorial and can use the same nesting sites for up to 20 years. This means yet another challenge for our monitored area when the same pairs return to breed next season!
Lenore Watermeyer: text and photo