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First report of a hatched, hand-reared, and released African oystercatcher


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The African oystercatcher Haematopus moquini is a near-threatened wader that is endemic to southern Africa. In the past, the species suffered a drastic decrease in nesting success due to human disturbance. We present the case report of an African oystercatcher that was hatched, hand-reared, and released in the Western Cape, South Africa. African oystercatchers are semi-altricial birds that tend to be highly sensitive to stress; as a result, strategies to minimize stress and the employment of surrogate parents and pre-release acclimatization are important to ensure post-release survival of hand-reared chicks. Considering the lack of literature on the incubation and hand-rearing of oystercatchers, this case report provides a basis for the development of hand-rearing techniques that might be useful for the protection of this and other threatened wader species.
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Received: 26 October 2017
Accepted: 11 December 2017
DOI: 10.1002/zoo.21395
First report of a hatched, hand-reared, and released African
Romy Klusener
Renata Hurtado
Nicola Stander
Nola J. Parsons
Southern African Foundation for the
Conservation of Coastal Birds (SANCCOB),
Cape Town, South Africa
Institute of Research and Rehabilitation of
Marine Animals (IPRAM), Espírito Santo, Brazil
Romy Klusener, 55 Pentz Drive, 7441, Cape
Town, South Africa.
The African oystercatcher Haematopus moquini is a near-threatened wader that is
endemic to southern Africa. In the past, the species suffered a drastic decrease in
nesting success due to human disturbance. We present the case report of an African
oystercatcher that was hatched, hand-reared, and released in the Western Cape, South
Africa. African oystercatchers are semi-altricial birds that tend to be highly sensitive to
stress; as a result, strategies to minimize stress and the employment of surrogate
parents and pre-release acclimatization are important to ensure post-release survival
of hand-reared chicks. Considering the lack of literature on the incubation and hand-
rearing of oystercatchers, this case report provides a basis for the development of
hand-rearing techniques that might be useful for the protection of this and other
threatened wader species.
The African oystercatcher Haematopus moquini (Charadriiformes:
Haematopodidae) is a near-threatened species with a global popula-
tion of c. 6,500 individuals breeding on the coasts of Namibia and
South Africa (BirdLife International, 2016a, 2017; Hockey, 1983;
Underhill, 2014). They breed on the rocky and sandy shoreline of
offshore islands and the mainland during the summer season, from
November to March. Because their breeding coincides with the peak
of the tourism season, they are vulnerable to the direct and indirect
effects of human disturbance. In the past, the African oystercatcher
population suffered a drastic decrease in nesting success that was
largely related to human disturbance (Jeffery, 1987). This is acutely
concerning since human disturbance and exploitation of the shore are
also believed to have been the primary factors leading to the extinction
of the Canarian oystercatcher Haematopus meadewaldoi (Hockey,
1987). Another significant threat to the African oystercatchers is the
frequent occurrence of oil spills along the South African coast, with
several oiling incidents affecting aquatic birds since 1948 (Whitting-
ton, 1999, Wolfaardt, Underhill, Altwegg, Visagie, & Williams, 2008).
There is no scientific literature on the techniques that may be used
for the incubation and hand-rearing of oystercatchers. Because these
are semi-altricial birds that rely on a prolonged bond with their parents
in order to fledge successfully (Elphick, Dunning, & Sibley, 2001), the
hand-rearing of oystercatcher can be particularly challenging. In this
study, we report the successful incubation, hand-rearing and release of
an African oystercatcher. The development of such husbandry
techniques may be valuable tools for the mitigation of environmental
impacts to the African oystercatcher, and may also provide a basis for
the development of hand-rearing techniques for other species of
waders that are even more acutely threatened, such as the Chatham
oystercatcher Haematopus chathamensis which has a global population
of c. 120 pairs (BirdLife International, 2016b).
On 20 January 2016, two African oystercatcher eggs (E01 and E02)
were removed from a nest at a construction site at the Ore Terminal in
Saldanha, Western Cape, South Africa (33°01S 17°59E). Both eggs
were placed horizontally in foam-cases designed for egg transporta-
tion and set in a portable incubator at 30 °C; clean towels were placed
on the base of the incubator and around the foam-cases to protect the
eggs (Figure 1a).
Eggs were admitted to the Chick Rearing Unit (CRU) of the
Southern African Foundation for the Conservation of Coastal Birds
(SANCCOB) (33°5002S 18°2929E). Egg measurements (E01:
63.5 × 41.8 mm, 56.9 g; E02: 59.8 × 36.5 mm, 56.4 g) were consistent
Zoo Biology. 2018;15. © 2018 Wiley Periodicals, Inc.
with previous studies for the species (Spiby, 2012; Underhill and Calf,
2005). Candling showed that both eggs contained yolk with no visible
embryo. Eggs were placed horizontally in an incubator at 36.5 °C and 45%
humidity (Grumbach
Compact S84 model 8015, Mücke, Germany) and
set to continually rotate eggs widthways (complete rotation every 2 hr);
additionally, eggs were manually rotated 180° lengthways every 24 hr.
Eggs were weighed daily and candled every 7 days.
E02 was discarded after 22 days of incubation because no embryo
development was observed. E01 developed adequately and pipped
externally after 23 days of incubation. The pipping egg weighed 50 g,
following a stable weight loss rate of 0.3 g per day. The pipping egg was
placed in a plastic container with soft paper towels and moved to a
hatcher incubator (same model) set at 36.5 °C with 60% humidity. The
chick hatched about 38 hr after external pipping was first noticed (total
of 25 days of incubation) (Figure 1b).
The chick was checked for external abnormalities, weighed (42 g),
placed in a container with clean soft paper towels, and relocated to the
incubatorfor 34 hrto dry out. When dry, it was tubedand received 1 ml
of probiotics [10 g/L Kyron Protexin
Soluble (Johannesburg, South
Africa),containing total viable count equal to or greaterthan 2 × 10
g of the following organisms: Lactobacillus plantarum, Lactobacillus
debrueckii bulgaricus, Lactobacillus acidophilus, Lactobacillus rhamnosus,
Bifidobacterium bifidum, Streptococcus salvarius thermophilus, and
Enterococcus faecium] and then transferred to a brooder crate placed
FIGURE 1 Hand-rearing of an African oystercatcher at SANCCOB. legend: (a) portable incubator used to transport eggs (African penguin
eggs are shown in the photograph); (b) newly-hatched African oystercatcher; (c) brooder crate under a heat lamp; (d) chick (arrow) bonding
with surrogate parent (plush toy resembling an adult African oystercatcher); (e) usage of surrogate parent to teach the chick how to eat by
pointing its beak at food items; (f) outdoor netted shaded sand pen; (g) portable acclimatization enclosure at the beach; (h) oystercatcher
approaching the surrogate parent after release; and (j) oystercatcher successfully feeding on a limpet (arrow) after having been released.
Photographs: (a, b, gi): Romy Klusener; c-f: Renata Hurtado
under a heat lamp (Figure 1c). The brooder crate (40 × 33 × 30 cm,
plastic) waslined with towels on the bottom andall sides; rubber matting
was placed under the bird to prevent splayed legs.
After 3 days the chick was moved to a larger plastic crate
(70 × 50 × 54 cm) with towels on the bottom, under a heat lamp.
Wading and bathing dishes of appropriate depth were provided
according to the size and age of the oystercatcher (Osnes-Erie, 2007).
The chick was exposed to direct sunlight for 15 min, three times a day.
Crates were washed and disinfected (quaternary ammonium) on a daily
basis. Table 1 summarizes changes in the external appearance of the
oystercatcher chick as it developed.
A plush toy resembling an adult African oystercatcher was used to
serve as a surrogate parentand was kept with the chick during the
entire hand-rearing process (from hatching to release). The chick
promptly bounded with it (Figure 1d), becoming stressed when the
plush had to be removed to be washed. The plush was also used to
teach the chick how to eat and drink/bath by pointing its red beak at
food pieces and water, to which the chick promptly responded
(Figure 1e). Audio recordings of wild African oystercatchers vocalizing
were also played to the chick; however, the chick did not exhibit
interest and did not appear calmer, therefore the playbacks were
discontinued. It is possible, however, that the audio recording that was
played did not represent the type of call that would be most suited to
elicit the desired behavioral response (see Baker & Hockey, 1984).
When the chick reached 42 days of age, it was moved to an
outdoor netted shaded sand pen (280 × 280 × 95 cm) (Figure 1f) during
days of good weather and returned to its indoors crate in the evening.
The pen had an artificial nest box (providing shelter and a hideout), the
plush toy, and a shallow water tray with stones. Both the outdoor and
indoor areas where the chick was kept were quiet and had a reduced
people flow.
Table 2 summarizes the feeding regime. The chick was weighed
daily before the first feed to monitor its development and calculate
the daily feeds. The diet included primarily fresh-caught limpet and
mussel, redbait, clam, shrimp, and squid based on the published diet
in the wild (del Hoyo, Elliott, & Sargatal, 1996; Hockey, Dean, &
Ryan, 2005; Scott, Dean, & Watson, 2012; Urban et al., 1986). Food
was offered in empty mussel shells with 0.5 ml of fresh water each
(Figure 1e). Food items were cut into small bite-sized pieces and
were gradually cut larger as chick grew, until it could open mussels
on its own and tear limpet meat from the shells. Supplementation
with Kyron Cani-cal
(1 g contains: vitamin A 400 IU, vitamin D3 30
IU, vitamin E 1 IU, iron 4 mg, zinc 1 mg, calcium 70 mg, phosphorus
58 mg), and Kyron Cani-vit
(vitamin A 100 IU, vitamin D3 10 IU,
vitamin E 3 IU, vitamin B1 0.02 mg, vitamin B2 0.05 mg, vitamin B6
0.04 mg, vitamin K 0.8 μg, vitamin B12 0.6 μg, calcium pantothenate
0.3 mg, biotin 0.03 mg, nicatinamide 0.6 mg, folic acid 5 μg, choline
bitartrate 10 mg, magnesium 0.4 mg, iron 1 mg, copper 0.08 mg,
manganese 0.1 mg, zinc 2 mg, iodine 0.03 mg, selenium 2 μg, sodium
chloride 5 mg, calcium 60 mg, phosphorus 60 mg, protein 0.3 g) was
added to every feed (c. 0.3 g each). The quantity of untouched food
at each meal was recorded, aiming to monitor the chick's appetite
and food preferences, and to verify if the weight gain was consistent
with the amount of food consumed.
At approximately 50 days of age the pre-release training was
initiated. The first stage was to take the bird to a large aviary
(10 × 4.5 × 3 m) once a day to exercise for 20 min (under supervision).
As the bird grew more comfortable in the aviary, this period was
gradually increased up to 8 hr per day. When the bird was
approximately 120 days-old, the second stage of pre-release training
was initiated. The bird was transported to a local beach in a large
portable enclosure (200 × 120 × 95 cm) for acclimatization (Figure 1g).
Duringthe entire hand-rearing process, the birdwas checked weekly
by a veterinarian and blood and fecal samples were regularly examined;
results showed no signs of on-going disease. Deworming treatment
(ivermectin 0.2 mg/kg PO and praziquantel 7.5 mg/kg PO) was given
15 days before release and repeated on the day before release.
Having passed all the release criteria (healthy, in good body
condition, waterproof feathers, normal behavior and flight, wariness of
predators and humans) (Osnes-Erie, 2007), a metal band (South
African Bird Ringing Unit SAFRING K48319) was placed on the right
leg of the bird. Baboon Point at Elands Bay (32°18'55S 18°18'56E)
TABLE 1 External changes observed during the development of a
hand-reared African oystercatcher chick
Age Changes
20 days-old Beak starts changing color, downy feathers only
30 days-old Juvenile feathers start to push through on wings,
head, and body
38 days-old Juvenile feathers growing through on tail, beak
halfway orange
47 days-old Orange beak with black tip
60 days-old All juvenile feathers grown through with no downy
feathers present, black tip on beak almost gone
67 days-old Beak completely orange
TABLE 2 Feeding regime used to hand-rear an African oystercatcher chick
Age Amount Food description 6hr 9hr 10hr 12hr 14hr 15hr 18hr 21hr
Ten percent of
body mass
Chopped seafood X X X X X X
47 to 139
Ten percent of
body mass
Whole or chopped (in large chunks) seafood.
Mollusks with shell slightly open
140 days
Ad libitum Mollusks (whole in shell) X X X
was chosen as the release site as it is known to be an important site for
juveniles and pre-breeding oystercatchers (Underhill, 2014).
On 25 July 2014, the162 days-old bird was taken to therelease site
at 08:00 hr. The release crate was left on the rocks for a few minutes for
the bird to acclimatize to the environment; the plush toy was placed a
short distance in front of the crate. When the lid was opened, the bird
hopped out and ran to the plush toy (Figure 1h). Shortly afterwards, it
started pokingits beak into mussels and limpets, as wellas taking baths in
a shallow rock pool. The oystercatcher flew off and continued searching
for food; it was seen to successfully catch a limpet (Figure 1i). After 6 hr
of observation, the bird was left to fend for itself.
The oystercatcher was re-sighted 3 weeks later at Baboon Point,
apparently in a fit and healthy condition (no further re-sightings have
been reported to SAFRING), indicating that the husbandry techniques
were successful to ensure that the bird could feed on its own and
survive after having been released.
Considering how fragile oystercatcher eggs are, the use of portable
incubator with foam-cases and towels was an efficient way to keep eggs
warm and preventing them from crushing/rupturing internal veins
during transportation. Incubation temperature was set according to the
temperature range (32.237.0 °C) described for natural African
oystercatcher nests in South Africa (Adams, Kerley, & Watson, 1999).
Assuming a total incubation weight loss of 1618%, as is consistently
observed in other avian species (Rahn & Ar, 1974), it maybe estimated
that the egg would haveweighed between 59.5 and 61.0 g when laid. An
egg of such mass would be expected to lose 0.3090.314 g per day
during incubation (calculations based on Rahn & Ar, 1974); the loss of
0.3 g per day therefore indicates that the incubation parameters
(temperature and humidity) were nearly optimal.
Despite oystercatcher chicks being fed by their parents for up to
a month (Elphick et al., 2001), the techniques we employed enabled
the bird to learn how to feed by itself since its first day of life.
Offering whole mollusks to the oystercatcher also developed its food
acquisition skills, as it was seen properly capturing and consuming
these items shortly after being released. All the implemented
measures ensured an appropriate weight gain curve (Figure 2), with
four stages of growth. Stage I began at hatching and extended up to
20 days of age, with a relatively slow weight gain (average daily
weight gain = 3.82% ± 6.04%), and body mass increased to 86 g over
this period (105% increase in 20 days). At stage II, between the ages
of 2140 days, there was a sharp increase in weight gain
(7.26% ± 4.44%), and the bird reached 344 g at 40 days of age
(300% increase in 20 days). At stage III, between the ages of 4180
days, weight gain slowed down (1.21% ± 4.59%) and body mass
increased to 512 g over this period (49% increase in 40 days). Finally,
a plateau was reached after 81 days, with virtually no weight gain
(0.18% ± 3.13%). The last weight obtained prior to release was 534 g
after 158 days (4% increase in 78 days).
Keeping the plush toy with the chick during the entire hand-
rearing process was found to be an efficient strategy to minimize
stress, since oystercatchers in the wild may remain with parents for up
6 months of age (Elphick et al., 2001). The plush toy was also
instrumental in inducing the chick to feed by itself very early (despite
the semi-altricial nature of this species) and preventing the human
imprinting, as the bird would become stressed/vocal when handled.
Furthermore, keeping human contact, noise and handling to a
minimum during daily routine was clearly beneficial to minimize stress.
In conclusion, despite the high sensitivity of this species the
incubation and hand-rearing techniques employed in this case were
successful and provide a basis for the future hand-rearing of
oystercatcher's eggs and chicks. These husbandry techniques might
prove valuable to protect the African oystercatcher and other
threatened waders.
We are grateful to all the interns and staff who worked in the CRU at
SANCCOB, and also to Dr. Natasha Ayres and Dr. Katrin Ludynia.
Thank you to Dr. Ralph Vanstreels for his constructive contributions on
this manuscript, to Dr. Les Underhill for the recommendation on the
ideal release site, and to Two Oceans Aquarium for providing limpets
and redbaits. We hugely thank the Chick Bolstering Project for helping
on funding the Chick Rearing Unit at SANCCOB.
The authors have declared no conflicts of interest.
Renata Hurtado
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FIGURE 2 The body mass curve of the african oystercatcher
chick hand-reared at SANCCOB from hatching to release
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How to cite this article: Klusener R, Hurtado R, Stander N,
Parsons NJ. First report of a hatched, hand-reared, and
released African oystercatcher. Zoo Biology. 2018;15.
This chapter presents a detailed guide to hand‐rearing techniques for raising shorebirds. It provides valuable information on record keeping, appropriate intervention, diet protocol, housing, and care and stabilization criteria considered throughout the hand‐rearing process. The chapter also presents common medical problems encountered in the shorebirds and appropriate solutions. In addition, it provides information on the processes involved in preparing the shorebirds for wild release.
Full-text available
The bulk ore carrier MV Treasure sank between Robben and Dassen islands off western South Africa in June 2000. Although releasing less oil than the Apollo Sea spill six years earlier, the number of African penguins Spheniscus demersus oiled (approximately 19 000) in the Treasure spill was almost double the number oiled in the Apollo Sea incident. The majority of oiled penguins was collected from Robben Island. The capture, stabilisation and transport of oiled penguins following the Treasure spill were substantially more successful than during the Apollo Sea rescue operation and resulted in an increase in the percentage of oiled penguins that were released back to the wild. In addition to the 19 000 oiled penguins that were caught, 19 500 un-oiled birds (12 345 from Dassen Island) were evacuated to Cape Recife, 800 km to the east, to prevent them from becoming contaminated. The evacuated birds returned rapidly to Dassen Island and many resumed breeding soon after their return. The restoration success (proportion of birds observed at Dassen Island that were recorded breeding) was substantially greater for evacuated birds than for de-oiled birds. Lightly oiled birds that were released without being cleaned had lower survival rates and were less successfully restored into the breeding population than de-oiled birds, especially if more than 5% of their body was covered in oil. Reproduction exerted a greater cost to de-oiled birds than to evacuated birds. A total of 1 787 orphaned chicks was hand-reared at two separate facilities on the mainland and were released at Robben and Dassen islands. The chicks did not necessarily return to the colony at which they were released. The survival rates and restoration success of chicks reared at the two facilities differed, probably as a result of one group being overfed. Despite the death of about 2 000 African penguins in the Treasure spill, and the substantial disturbance that resulted from the rescue operation, the penguin colonies at Robben and Dassen islands increased by 18% and 26% respectively in the year following the spill. This increase was attributed to a significant increase in the biomass of anchovy Engraulis encrasicolus and sardine Sardinops sagax in 2001. These findings highlight the importance of preventing oil spills in the first place, and in the event of a large oil spill, the conservation value of evacuating un-oiled penguins to minimise their risk of becoming contaminated.
Full-text available
Adams, N.J., Kerley, G.I.H. & Watson, J.J. 1999. Disturbance of incubating African Black Oystercatchers: is heating of exposed eggs a problem? Ostrich 70(3&4): 225–228.We measured temperatures of incubated and exposed eggs of African Black Oystercatchers Haematopus moquini nesting in coastal dunes, Algoa Bay, South Africa through three of the 10 hottest days of summer during the 1994/95 breeding season. Mean incubation temperature was 34.4 ± 0.7°C (range: 32.2–37.0; n=3). The average maximum temperature attained by exposed dummy eggs, averaged higher at 37.4 ± 2.7°C (n=5). The absolute maximum recorded for exposed eggs was 40.1°C. These temperatures are within lethal limits measured for other birds and suggests that heating of exposed eggs after disturbance of incubating was not a direct factor in explaining variation in breeding success of oystercatchers in the Alexandria Dunefield, Algoa Bay.
Since 1968, the Southern African Foundation for the Conservation of Coastal Birds (SANCCOB) based in Cape Town has cleaned, on average, between 200 and 2000 African Penguins Spheniscus demersus per year. Most of these were banded prior to release, so that the success of the cleaning procedures could be monitored. Survival of cleaned and non-oiled African Penguins was compared from an analysis of recoveries of banded individuals. Over a period of 10 years, time elapsed between banding and recovery did not differ significantly between cleaned and non-oiled penguins, as shown by a randomisation test. Results from this study were compared with banding recovery data for certain North American seabirds. Some rehabilitated African Penguins were shown to be amongst the oldest known individuals of this species in the wild. Cleaning oiled African Penguins is considered to make a worthwhile contribution to the conservation of a vulnerable, endemic species.
A study of the diet and habitat used by African Black Oystercatchers Haematopus moquini at De Hoop Nature Reserve, Western Cape Province, South Africa, showed that the area is important as a mainland habitat for the birds. Within the study site, the central sector, with rocky/mixed habitat and extensive wave-cut platforms, was a particularly important oystercatcher habitat, even though human use of this area was high. This positive association was apparently linked to the diversity of potential food items and the abundance of large brown mussel Perna perna, the major prey. In contrast, the diversity of prey species was lower in mixed/sandy habitat where the dominant prey was white mussel Donax serra. The diversity of prey (28 species) for the combined study area is higher than that recorded at any one site for the African Black Oystercatcher previously. This total includes several food items not previously recorded for the species (relatively large numbers of Cape false limpets Siphonaria spp. and low numbers of African periwinkle Nodilittorina africana, smooth turban shell Turbo cidaris, abalone Haliotis midae, spiral-ridged siffie H. parva and oblique arkshell Barbatia obliquata). The study shows that the establishment of the marine reserve was associated with increases in the modal sizes of the main prey species consumed.
The African Black Oystercatcher (Huematopus moquinz) is endemic to southern Africa, occurring as a breeding species from the Hoanib River mouth in Namibia around the Cape of Good Hope to Mazeppa Bay, Transkei (Hockey 1983a, S. Braine, in litt.). H. moquini has wholly mel-anistic plumage and, like other Old World species, adults have scarlet it-ides, bright coral-pink legs and jet-black feathers on the back. Its sys-tematic relationships are problematical, some authorities (e.g., Peters 1934; Larsen 1957) preferring to treat it as a subspecies of the European Oys-tercatcher (H. ostrulegus), whereas others accord it full species status (e.g., Heppleston 1973; Clancey 1980). Recent studies have revealed details of the general biology ofH. moquini (Summers and Cooper 1977; Hockey and Cooper 1980; Hockey 198 la, b, 1982, 1983a, b, c, 1984; Hockey and Branch 1983, 1984; Hockey and Underhill 1984). Despite this wealth of ecological knowledge, the only report of the breeding behavior of this species is that of Hall (1959) which is based on relatively few birds and does not cover the repertoire of known behaviors of oystercatchers (see Makkink 1942, Williamson 1943, Miller and Baker 1980). Vocalizations of H. moquini have not been studied previously. In this paper we describe the behavior and vocalizations of African Black Oystercatchers during the breeding season in the south-western Cape Province, South Africa. Our ultimate goal is to provide comparative data to assist in clarifying relationships within the Haema-topodidae (Baker 1974, 1975, 1977). METHODS Observations of H. moquini were made principally during the breeding season early in 1982 (January 6-8, 13-15, and 20-24) at Marcus Island (33%2' S, 17"58' E) and Malgas Island (33"03' S, 17"55' E) in Saldanha Bay, southwestern Cape Province, South Africa. General observations on the behavior of birds on these sites in 1979 and 1980 were made by the second author. Motion pictures of displays were taken with an Elmo super 8 mm sound camera at 24 frames/set to ensure good sound fidelity. Behavioral interactions among three territorial pairs were filmed from a portable canvas hide located within 20 m of the birds. Displays of birds with young were filmed at close range (ca 5-20 m) with the observers in full view. Figures of various displays were prepared by tracing images from still-frame projections. Descriptions of all display behaviors are based on terminology suggested by Cramp et al. (1983).
Hockey, P. A. R. 1983. Aspects of the breeding biology of the African Black Oystercatcher. Ostrich 54:26-35. Fifty-five pairs of African Black Oystercatchers Haematopus moquini bred at Marcus Island in 1979–1980. Sixteen pairs laid replacement clutches: the mean interval between loss of the fist clutch and laying of a replacement clutch was 22,2 days. Mean inter-nest distance was 19,4 m. The modal clutch size was 2, with a mean of 1.74. Mean dimensions of 105 eggs were 60,7 × 40,l mm and mean fresh egg mass was 55,s g. There were differences in egg mass and dimensions between eggs in one- and two-egg clutches. Rate of egg loss was high, due mainly to depredation by Kelp Gulls Larus dominicanus promoted by human disturbance. Fledging success was lower at a disturbed site than at undisturbed sites, with highest chick mortality occurring in the first week of life. Mortality of first-year birds of eight days and older was estimated at 48% and 69% in two successive seasons. All juvenile birds dispersed from the natal sites, and were resighted up to 168 km away. Dispersed juveniles were concentrated at the edge of an area of high oystercatcher density.
There is no material evidence for the survival of the endemic Canarian black oystercatcher Haematopus meadewaldoi of the Canary Islands subsequent to 1913. An expedition to the eastern Canary Islands in 1985 failed to find any trace of the bird, and likely factors contributing to the species' extinction were investigated. There has been a progressive desertification of the eastern Canary Islands in the past few centuries, accelerated more recently by changing land-use practices. This has led in turn to an increased dependence of the islands' inhabitants on marine resources as food, with concomitant modification of intertidal invertebrate communities. Habitat availability was the ultimate factor limiting population size in H. meadewaldoi, but the extinction of the species was probably precipitated by increasing disturbance and competition with man for food.