Page 320 - Atlas Sea Birds Ver1

surveys (Pichegru et al. 2017). Some of these issues are
more easily addressed than others. For example, harvests
of guano have been stopped (Tom et al. 2024) and seals
can be prevented from displacing birds by manning islands.

References

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Berry HH, Seely MK, Fryer RE. 1974. The status of the Jackass
African Penguin juveniles and adults (photo M van Onselen) Penguin Spheniscus demersus on Halifax Island off South
nd
colonies decrease (Ryan et al. 2012, Makhado et al. 2021) West Africa. Madoqua 2 Series 3: 27–29.
and a higher probability of extinction of smaller colonies BirdLife International. 2000. Threatened birds of the world. Lynx
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(Crawford et al. 2001), priority attention should be given to BirdLife International. 2020. Guidelines for the application of the
maintaining and growing these larger colonies (Crawford IBA criteria. Final version, July 2020. 18 pp. Downloaded
et al. 2022). If a ‘super site’ is defined as a site that holds from http://datazone.birdlife.org/ on 20 May 2022.
≥ 1% of the present African Penguin population there would BirdLife International. 2022. Species factsheet: Spheniscus
be 10 of these (Table 2). demersus. Downloaded from http://www.birdlife.org on 08
As indicated above, the major driver of the large December 2022.
decreases of African Penguins in the latter part of the 20 Campbell KJ, Steinfurth A, Underhill LG, Coetzee JC, Dyer BM,
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century and the early 21 century was a scarcity of high- Ludynia K, Makhado AB, Merkle D, Rademan J, Upfold L,
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Delayed breeding and longer fledging periods are likely Crawford RJM, Dyer BM. 1995. Responses by four seabirds to a
to reduce the number of clutches produced in a season fluctuating availability of Cape anchovy Engraulis capensis
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(Crawford et al. 2022). Three interventions to alleviate interrelationships off the coasts of South West and South
food scarcity have been proposed: closures to purse- Africa. Biological Conservation 14: 85–109.
seine fishing around key breeding sites, implementation Crawford RJM, Cruickshank RA, Shelton PA, Kruger I. 1985.
of ecosystem thresholds below which fishing is reduced Partitioning of a goby resource amongst four avian predators
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distributions of prey (Crawford et al. 2022). Advances have of an intense, perennial upwelling system. South African
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Hoop Nature Reserve (Dyer et al. 2024). Competition for space: recolonising seals displace
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by oil spills (Crawford et al. 2000a); human disturbance Crawford RJM, Williams AJ, Hofmeyr JH, Klages NTW, Randall
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2012); outbreaks of disease (Molini et al. 2019); adverse Meÿer MA, Randall RM, Underhill LG, Upfold L, van Dalsen
weather conditions (Kemper 2015); and probably seismic AP, van der Merwe E, Whittington PA, Williams AJ, Wolfaardt

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