The roles o f i h e El rVi% ohenomenon. a ccssoiion o f uowellin~. and of . . ". humonfishing in limiringpopulorions o/Peiuuion guano birds (Gummy cormorant Phalacrocoran bougainviiiii, Peruuian booby Sulv varicgata, and Peiuoian brown...
moreThe roles o f i h e El rVi% ohenomenon. a ccssoiion o f uowellin~. and of . . ". humonfishing in limiringpopulorions o/Peiuuion guano birds (Gummy cormorant Phalacrocoran bougainviiiii, Peruuian booby Sulv varicgata, and Peiuoian brown pelican Pelccanus accidentalis thagur) were intiesrigorcd using historical records ond the scicnrifc lilernrure. In n o r n d years, the combinedpopulorions ojrlie lhrce species showed on 18% incrcose per year. El Nin'or occurred oi approximalelyfiae-pnr inzervnlsondcausedapopulorion decrease o,fl7% and35% desertion of nesting oreas. In sewre El N i i m o! npproximaicly 12-ycor inieruals, [here w s a mean decrease 0/47% ondcomplere nesri~~gjnilare. El Niios mried in seteriry nnd a possiblr explanorion is prermied. In non-El Nrio years, commerciolfishing did not d i r e a h conirol bird popularions rhrvugh srarooriort giodiilis or drowning in nerr Increased commercial fishing apporenily led to decreased nesring suecms: the grenrcr rhe quanriry qifish landed, ibc lower !he percoirnge inereose of rhe birdpopu/o!ion rho[ yenr. Shorr-liwii, hheauilv-fi5hed smcies such as anchoucio ore in eonsionr . . danger qfpopulorion collnpse during years of occasional, unpredicroble rcproduciiaejoilure. Birdpopulations could be maintained as bu//ers ro prevent terminnlly-de.vesrriiciiac orerfishing by humans. 227 Bid Co,i$mu. 0W&3207!83/0026-0227ISO3~00 0 Applied Scicncc Publirhcrr Lrd, England, 1983. Printed in GieaL Britain
