Understanding recruitment in demersal fish requires determination of larval survival and delivery to appropriate settling habitats. Sanddabs Citharichthys sp. are an abundant neritic fish of Central California, an area of persistent upwelling. 'Upwelling shadows' develop in the lee of coastal promontories, retain surface waters, and may promote spatial variation in fish settlement. To test this hypothesis, we studied the diet and foraging dimensions of a seabird (Cepphus columba) specializing in sanddab consumption at windward and leeward sites over a 6 yr period. We integrated the bird's take of sanddab with information on upwelling intensity and variability and sanddab larval abundance based on net sampling. Seabird diet at both sub-colonies was variable, but dominated by Age 1 sanddabs. Sanddabs were more prevalent in the diet of guillemots at the leeward site, and diet was more variable at the windward site. Persistent upwelling led to regional increases in sanddab larval abundance which, in turn, resulted in enhanced recruitment to leeward waters, as reflected in seabird diet. Pulsed upwelling was related to apparent increased recruitment in windward waters. This study is one of the first to suggest that seabird diet can be used as an indicator of spatial variability in recruitment and settlement of demersal forage fish.

No abstract

Noninvasive, safe, quick marking of individual animals using distinctive colors that are highly visible and persistent is a valuable methodology, but practical techniques and permanent safe dyes are lacking. Here we describe a novel, remotely controlled dye machine to rapidly mark stationary animals in predictable locations, such as birds sitting on nests on the ground or mammals at a den or burrow site. From the month of June when birds were on eggs, using the machine, we spot-dyed 77 California least terns (Sternula antillarum browni) at a colony in California, USA, in 4 days without handling them. Concomitantly, we developed a suite of permanent (until molt or shedding), mainly phthalocyanine dyes that are incorporated chemically into feathers or fur of animals and cannot be preened or rubbed off, which have never been used before to dye animals. We found no toxicity of the dyes during in vivo testing over 1 month. This method of remote marking with permanent dyes should prove to be a useful method in animal ecology for distinguishing among individuals with minimal disturbance. Ó 2017 The Wildlife Society.

No abstract

No abstract