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Monge-Najera, J.

Publications and source records attributed to Monge-Najera, J..

4 recordsLinked to original sources
bioRxiv2019

Are tropical reptiles really declining? A six-year survey of snakes in Drake Bay, Costa Rica, and the role of temperature, rain and light

Introductionstudies in the last two decades have found declining snake populations in both temperate and tropical sites, including informal reports from Drake Bay, Costa Rica.\n\nObjectiveto investigate if reports of decreasing snake populations in Drake Bay had a real basis, and if environmental factors, particularly temperature, rain and light, have played a role in that decrease.\n\nMethodswe worked at Drake Bay from 2012 through 2017 and made over 4000 h of transect counts. Using head flashlights we surveyed a transect covered by lowland tropical rainforest at an altitude of 12-38 m above sea level, near the Agujas River, mostly at 1930-2200 hours. We counted all the snakes that we could see along the transect.\n\nResultssnake counts increase from August to September and then decline rapidly. The May snakes/rainfall peaks coincide, but the second snake peak occurs one month before the rain peak; we counted more snakes in dry nights, with the exception of Imantodes cenchoa which was equally common despite rain conditions. We saw less Leptodeira septentrionalis on bright nights, but all other species were unaffected. Along the six years, the number of species with each diet type remained relatively constant, but the number of individuals declined sharply for those that feed on amphibians and reptiles. We report Rhadinella godmani, a highland species, at 12-38 m of altitude.\n\nConclusionnight field counts of snakes in Drake Bay, Costa Rica, show a strong decline from 2012 through 2017.

ecology↗
bioRxiv2018

The conservation status of Costa Rican velvet worms (Onychophora)

Charismatic species, like the panda, play an important role in conservation, and velvet worms arguably are charismatic worms. Thanks to their extraordinary hunting mechanism, they have inspired from a female metal band in Japan, to origami worms in Russia and video game monsters in the USA.\n\nObjectiveTo assess their conservation status in Costa Rica.\n\nMethodswe located all collection records of the 29 known species from the Onychophora Database in the map of the Costa Rican Conservation Network.\n\nResultsWe found that seven species are protected inside forest reserves, five in Protected Zones, four in Wildlife Refuges, two in National Parks and one, Principapillatus hitoyensis, in a strictly pristine Biological Reserve. The largest species in the world, Peripatus solorzanoi, occurs both inside a Forest Reserve and in protected private land. Protection inside Costa Rican nature areas is enforced year round by personnel that includes armed guards, and is supported by educational programs in surrounding communities. Twelve species have not been found in protected areas, but in Costa Rica, all biological species, named and unnamed, are protected by law and cannot be legally collected, or exported, without technically issued permits.\n\nConclusionLike in the only other country with similar information (New Zealand), the conservation of onychophorans seems to be of least concern for at least two thirds of the known species. Epiperipatus isthmicola, recently rediscovered after a century of absence in collections, can be considered Threatened because nearly all of its natural habitat has now been covered by a city.

ecology↗
bioRxiv2018

The role of substrate type, moisture and temperature on the vertical growth of terricolous lichens

Lichens are traditionally divided into short \"crustose\", intermediate \"foliose\" and tall \"fruticose\" types, a practice that hides a growth continuum. Substrate, temperature and water are thought to affect vertical growth, but such factors are difficult to measure, because, for example, the water actually available to lichens does not match rainfall patterns or even ground water levels. To reliably assess the effect of those factors, I recorded temperature, moisture, and substrate in and under individual terricolous lichen colonies in 60 fixed quadrats on April, August, October, and December of 2015 (Cerro de la Muerte, Costa Rica, 9{degrees}33'N; 83{degrees}45'W). The measurements were taken inside the colonies themselves (rather than on the general environment), covering an annual cycle of the relatively simple paramo habitat, where animals and vegetation have less impact than in lower ecosystems. The hypotheses were that lichens would grow taller on softer, warmer, and moister ground; on the Caribbean versant; and on the rainy season. Results matched the hypotheses, with one exception: lichens on soft ground were not taller than those on rock. Caribbean colonies were, on the average, 7 cm taller than those on the drier Pacific versant. Physiologically available water seems to be the main determinant of lichen vertical growth: more water means taller lichens and greater protection from climatic change for both the lichens and their microcommunities.

ecology↗