Artificial nests enhance the breeding productivity of African Penguins (<i>Spheniscus demersus</i>) on Robben Island, South Africa

Sherley, Richard B.; Barham, Barbara J.; Barham, Peter; Leshoro, T. Mario; Underhill, Les G.

doi:10.1071/mu11055

Cited by 41 publications

(41 citation statements)

References 32 publications

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“…) in which breeding success was assumed to be similar to the long‐term average at Robben Island (nest content survival of 0.70; Sherley et al . ).…”

Section: Discussionmentioning

confidence: 97%

Age‐specific survival and movement among major African Penguin Spheniscus demersus colonies

Sherley

Abadi

Ludynia

et al. 2014

Ibis

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Reliable estimates of survival and dispersal are crucial to understanding population dynamics, but for seabirds, in which some individuals spend years away from land, mortality and emigration are often confounded. Multistate mark–recapture methods reduce bias by incorporating movement into the process of estimating survival. We used a multistate model to provide unbiased age‐specific survival and movement probabilities for the Endangered African Penguin Spheniscus demersus based on 5281 nestlings and 31 049 adults flipper‐banded and resighted in the Western Cape, South Africa, between 1994 and 2012. Adult survival was initially high (≥ 0.74) but declined after 2003–2004 coincident with a reduction in the availability of Sardine Sardinops sagax and Anchovy Engraulis encrasicolus on the west coast of South Africa. Juvenile survival was poorly estimated, but was lower and more variable than adult survival. Fidelity to the locality of origin varied over time, but was high in adults at Robben and Dassen islands (≥ 0.88) and above 0.55 for juvenile and immature Penguins at all localities. Movement occurred predominantly during 1994–2003 and was indicative of immigration to Robben and Dassen islands. Our results confirm that a prolonged period of adult mortality contributed to the observed decline in the African Penguin population and suggest a need for approaches operating over large spatial scales to ensure food security for marine top predators.

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“…) in which breeding success was assumed to be similar to the long‐term average at Robben Island (nest content survival of 0.70; Sherley et al . ).…”

Section: Discussionmentioning

confidence: 97%

Age‐specific survival and movement among major African Penguin Spheniscus demersus colonies

Sherley

Abadi

Ludynia

et al. 2014

Ibis

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“…Numbers of chicks in crèches were divided by two, the usual clutch size, to estimate the number of nest sites they represented, with remainders taken to represent an additional site, e.g., crèches of five and six chicks would both be taken to represent three nests (Shelton et al, 1984). As is the case for cormorants (see below), because not all eggs hatch and broods may be reduced (e.g., Sherley et al, 2012a), this is likely to underestimate the actual number of nests represented by chicks in crèches and hence lead to a conservative estimate of the overall number of birds breeding. Furthermore, brood reduction may vary depending on conditions during breeding.…”

Section: Methodsmentioning

confidence: 99%

A changing distribution of seabirds in South Africaâ€”the possible impact of climate and its consequences

et al. 2015

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In the southern Benguela ecosystem off South Africa, there were recent shifts to the south and east in the distributions of three forage resources (anchovy, sardine, rock lobster), which probably were influenced by environmental change although fishing too may have played a part. In this study, we review information on trends in distributions and numbers of eight seabirds breeding in South Africa. For five species that feed predominantly on anchovy, sardine or rock lobster, their populations off northwest South Africa decreased markedly. For three of these species, which exhibit behavioral inertia and have restricted foraging ranges when breeding (African penguin, Cape cormorant, bank cormorant), there were large decreases in their overall populations in South Africa. Conversely, for two showing more plasticity and able to range over wide areas or move between breeding localities (Cape gannet, swift tern) there were increases. It is thought that movement of forage resources away from the northern islands led to a mismatch in the distributions of breeding localities and prey of dependent seabirds off western South Africa and to attempts by several species to establish colonies on the southern mainland closer to food resources. There also were shifts to the south and east in the distributions of three seabirds that do not compete with fisheries for prey (crowned cormorant, white-breasted cormorant, kelp gull), suggesting some environmental forcing, but decreases of these species off northwest South Africa were less severe and populations in South Africa remained stable or increased in the long term. It is likely, because many fishing plants are located in the northwest, that there was increased competition between seabirds and fisheries for prey as forage resources moved south and east. Potential interventions to mitigate the adverse impacts of distributional changes for seabirds include allocations of allowable catches of shared forage resources at regional levels, closures to fishing around impacted seabird colonies and establishment of new colonies nearer to the present location of food.

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“…Artificial nest chambers have been successfully used with a wide range of seabirds (Bolton et al, 2004;Sherley et al, 2012) and have been shown to provide similar, or improved breeding performance compared to natural nest sites, particularly in suboptimal habitat (Bolton, 1996;Bolton et al, 2004;Byrd et al, 1983;Priddel and Carlile, 1995). Artificial burrows benefited Chatham petrels by stabilising fragile sites, reducing inter-specific interference, and protecting burrows from adverse weather conditions.…”

Section: Use Of Artificial Burrowsmentioning

confidence: 98%

Recovery of the endangered Chatham petrel (Pterodroma axillaris): A review of conservation management techniques from 1990 to 2010

Gummer

Taylor

Wilson

et al. 2015

Global Ecology and Conservation

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a b s t r a c tConservation of gadfly petrels, some of the most threatened seabirds, is frequently dependent on long-term research and management. We review 20 years of a program preventing the extinction of the Chatham petrel (Pterodroma axillaris), a New Zealand endemic once declining due to intense burrow competition from another native seabird. Breeding success in the early 1990s was unsustainably low (10-30%). Recovery measures started in 1992 when Chatham petrel burrows were converted and artificial entrances blockaded to exclude broad-billed prions (Pachyptila vittata). Pair and burrow fidelity were enhanced, though prions still posed a threat during Chatham petrel chick-rearing. Breeding success improved when prions were culled, however a less intensive and contentious solution was to introduce burrow flaps in 2001 which reduced interference from prospecting prions. Subsequently, breeding success increased to a mean 80% per annum. Finding burrows, primarily using radio-telemetry, increased those under management from eight in 1990 to 217 in 2010 when spotlight surveys indicated 72% of juvenile birds had fledged from managed burrows. Chick translocations to two other islands and increasing population size (from 200-400 birds in 1990 to an estimated 1400 birds by 2010) has improved the species IUCN status from Critically Endangered in 1990 to Endangered in 2013.

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Artificial nests enhance the breeding productivity of African Penguins (Spheniscus demersus) on Robben Island, South Africa

Cited by 41 publications

References 32 publications

Age‐specific survival and movement among major African Penguin Spheniscus demersus colonies

Age‐specific survival and movement among major African Penguin Spheniscus demersus colonies

A changing distribution of seabirds in South Africaâ€”the possible impact of climate and its consequences

Recovery of the endangered Chatham petrel (Pterodroma axillaris): A review of conservation management techniques from 1990 to 2010

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