Distribución, abundancia y conservación de la avifauna de las islas Marietas, Nayarit, México

Abstract

AN ANALYSIS OF THE SPECIES RICHNESS, ABUNDANCE, POPULATION FLUCTUATIONS, AND REPRODUCTIVE CYCLES OF BIRDS IN THE MARIETAS ISLANDS, NAYARIT, MEXICO, IS PRESENTED. THE STUDY COMPROMISED 24 FIELD TRIPS FROM 1987 TO 1999. THE BRIDLIFE OF THE ISLANDS INCLUDES 85 SPECIES; 57 FOR ISLA REDONDE, AND 62 FOR ISLA LARGA. THE HIGHEST SPECIES RICHNESS WAS RECORDED IN APRIL AND MAY AND THE LOWEST IN OCTOBER AND NOVEMBER. TEMPORARY RESIDENT BRIDS ARE THE MOST ABUNDANT SPECIES AND THE LEAST ARE PERMANENT RESIDENT BIRDS; SUMMER RESIDENTS CONTRIBUTION IS IMPORTANT WHEN RATING NUMBER OF SPECIES AND INDIVIDUALS. THE RESULTS SHOW A HIGHEST SPECIES RICHNESS THAN IN 1981 AND HIGHER SAMPLING EFFORT THAN 1961. THE POSSIBLE EXPLANATION OF THESE ARE DISCUSSED. SIX SPECIES CONSTITUTE NEW RECORDS FOR THE STATE OF NAYARIT. NESTING COLONIES OF FOUR SPECIES ARE THE LARGEST IN THE COUNTRY, AND TWO OF THESE ARE ALSO THA LARGEST POPULATIONS IN THE PACIFIC. AN URGENT NEED TO PRESERVE THE ISLANDS IS DISCUSSED.