In nest-building species, offspring survival and reproductive success of parental individuals are strongly influenced by nest quality. Thus, quantifying the influence of abiotic conditions on nest integrity is important to predict the effects of weather variability on the fitness of parental individuals. Here, we investigated how rainfall affects nest integrity and how nest integrity influences males’ attractiveness and nest tenure. Our study species was the harvestman Quindina limbata, in which males build mud nests on fallen logs and protect the eggs against predators and fungi. Our data set comprises 12 months of regular inspections of 149 nests in a Costa Rican rainforest. We found that almost 50% of the nests were destroyed by rainfall. The drag force caused by rainfall running on the fallen log surface negatively affected nest integrity. Fungi cover on nests was influenced by an interaction between rainfall and nest position on the fallen log. Irrespective of their body size, males in nests with high integrity received more eggs than males in nests with low integrity. Fungi cover did not influence the number of eggs received by the males. Finally, nest integrity and fungi cover did not affect nest tenure, but males that did not receive eggs for a long time tended to abandon their nests. Considering that intense rainfall occurs all year long in tropical forests, males should build their nests in protected sites that preserve nest structure. Protected sites may keep nest structure better preserved, improve offspring survival, attract more females, and increase males’ reproductive success.

Sheet-webs are built by a variety of unrelated spiders. Some of these spiders are common, but information on their web construction behavior is scarce. This study describes the sheet-web construction behavior of Melpomene sp. (Agelenidae) and the sites where webs are built. I recorded the beginning of sheet-web construction by several spiders and analyzed photographs of webs in the field and the laboratory. Web construction consisted basically of two alternating behaviors: laying support threads and the filling in the sheet. These behaviors were repeated during several construction sessions until the available area was filled, or until the web reached approximately 80 cm^. Apparently the spider uses both ampullate and aciniform lines for web construction, contrary to a recent description.Keywords; Web building behavior, funnel web, ampullate lines, aciniform lines Rojas, Andrés. 2011. "Sheet-web construction by Melpomene sp.

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