Population structure and dynamics, breeding activity and phenology of the blue‐sided treefrog (Agalychnis annae)

Agalychnis annae is a species endemic to Costa Rica and Panama with populations shrinking or disappearing from several locations. We studied the reproduction of a relict population of A. annae in a 1,300 m2 natural pond in Costa Rica during 2007–2008. We marked adults with a visible implant alphanumeric tag injected in the thigh. We measured reproductive effort considering calling males per night and per hour, number of pairs in amplexus, and number of egg masses. We summed 366 individual observations: 57% juveniles, 39% adult males, and 4% adult females. Average snout–vent length was 29 mm (juveniles), 63 mm (males), and 78 mm (females). Sex ratio (males:females) was 4.85:1, while operational sex ratio varied between one and six males per female when both sexes were present at the pond. Maximum estimated census population size varied between 27 and 59 individuals, with a Ne = 43.11. Calling activity occurred mostly from 1800–2000 h, and we counted 65 egg masses. Number of adults and calling males were positively correlated with accumulated rainfall and average temperature. Number of egg masses was positively correlated with the number of adults, accumulated rainfall, and average temperature. The causes of the long‐term population decline must be identified to conserve A. annae and similar species, as well as establishing long‐term monitoring programs. Required conservation actions include translocation individuals from risky areas, creation of artificial ponds to increase ecological connectivity, elimination of introduced species, particularly in small habitat remnants, and establishment of ex situ conservation programs. in Spanish is available with online material. Resumen Agalychnis annae es una especie endémica de Costa Rica y Panamá con poblaciones que disminuyen o desaparecen de varios lugares. Estudiamos la reproducción de A. annae en un estanque natural de 1,300 m2 en Costa Rica durante 2007–2008. Marcamos individuos adultos con una etiqueta alfanumérica de implante visible inyectada en el muslo. Medimos el esfuerzo reproductivo basados en el número de machos que vocalizaban por noche y por hora, número de parejas en amplexo y número de masas de huevos. Sumamos 366 observaciones individuales: 57% juveniles, 39% machos adultos y 4% hembras adultas. La LHA promedio fue de 29 mm (juveniles), 63 mm (machos) y 78 mm (hembras). La proporción de sexos (machos:hembras) fue de 4.85:1, mientras que la proporción operacional de sexos varió entre 1–6 machos po