Dataset used for manuscript, <b>"</b><b>Seasonal Abundances of Coastal Megafauna in Northwest Costa Rica Revealed Using Drones</b><b>"</b>

<p dir="ltr">Nearshore environments are physically dynamic and critical habitats for marine megafauna, yet they are under intense anthropogenic pressures. Here, we used drones to assess seasonal abundances of marine megafauna within Cabuyal bay in northwest Costa Rica. Between September and March 2017 – 2018 and 2018 – 2019, we flew sawtooth transects parallel to the shore at distances of (1) 0 – 100 m (n = 20) and (2) 100 – 200 m (n = 16). Across 36 surveys, we observed 1,891 megafauna individuals, comprising at least 15 unique taxa<b>. </b>Importantly, 11 of the identified species are listed as threatened by the IUCN Red List. When grouping taxa into broader categories (Rays, Bony Fishes, and Reptiles), rays were the most diverse taxonomic grouping with at least 8 unique taxa while bony fishes were the most abundant consisting of 76 % of individuals. Total megafauna abundance was statistically significantly higher in the dry season (December–February) than the wet season (September–November) with the exception of <i>Mobulid </i>rays and sea turtles. Species richness and abundance were positively correlated with wind-driven upwelling and local productivity in the dry season. 65% of all species observations were made within the 0 – 100 m transects. This pattern was mirrored for bony fish (72% in 0 100 m) and marine reptiles (66% in 0 – 100 m), though not for rays (38% in 0 – 100 m). Our results also indicate that Cabuyal bay is an important site for a diverse array of ray species in northern Costa Rica and this area should be considered for local protective measures.</p>