Conspecific cues encourage Barn Swallow (Hirundo rustica erythrogaster) prospecting, but not nesting, at new nesting structures

Shed-like structures are being built to provide Barn Swallow (Hirundo rustica erythrogaster) nesting habitat in response to population declines. However, Barn Swallow use of these structures is unavailable in the literature. We conducted three manipulative experiments to test if adding conspecific cues (i.e., vocalizations and decoys) to newly-built structures affected prospecting visits by Barn Swallows (1) during pre-breeding, (2) during post-breeding, and (3) during or after broadcasts of vocalizations compared to before broadcasts. Additionally, we monitored nesting following pre- and post-breeding cues. We built one nesting structure with and one without conspecific cues at each of 10 study sites in southern Ontario, Canada where nesting habitat was recently lost. We detected about twice as many Barn Swallows immediately after conspecific broadcasts compared to before. We did not find substantial differences in abundance and interactions with new nesting structures for other comparisons involving conspecific cues. Following pre-breeding cues at 10 sites, six nests were built in three of 10 structures treated with conspecific cues, compared to five nests in four of 10 structures without cues. In the subsequent breeding season following post-breeding cues at eight sites, four nests were built in two of eight structures treated with conspecific cues, compared to four nests in three of eight structures without cues. Conspecific vocalizations appeared to increase prospecting behaviour, but not the number of nests, at new nesting structures. The paucity of nests on new structures suggests that building shed-like structures may not be an effective method of mitigating loss of nesting habitat.

Biological Features of Neoseiulus californicus (Acari: Phytoseiidae) Feeding on Schizotetranychus oryzae (Acari: Tetranychidae) Kept on Rice Leaves

Schizotetranychus oryzae Rossi de Simons attains pest level in rice crops. This study aimed to evaluate the biological features of Neoseiulus californicus (McGregor) feeding on S. oryzae on leaves of flooded rice. We also evaluated N. californicus behavior in response to S. oryzae and conspecific cues. Thirty-two eggs were individually placed in arenas on rice leaves and fed on S. oryzae for the biological test. Three cultivars were used to test the behavior of N. californicus in response to S. oryzae and conspecific cues. The intrinsic rate of increase (rm) of the predator feeding on S. oryzae was 0.21 female/female/day. Schizotetranychus oryzae was considered a suitable prey for N. californicus under laboratory conditions. The results obtained in behavioral tests showed that N. californicus preferred laying eggs on leaves uninfested by S. oryzae and it did not show oviposition preference in arenas with conspecific predator cues. This predator was found in all rice cultivation areas in the state of Rio Grande do Sul, Brazil. Neoseiulus californicus proved to be a control agent for S. oryzae.

Comparable cross-taxa risk perception by means of chemical cues in marine and freshwater crustaceans

Rapid identification of predation risk and modification of subsequent behaviour is essential for prey survival. In low-visibility aquatic environments, chemical cues emitted by hetero- and conspecific organisms may be an important information source if they identify risk or alternatively, indicate safety or resource availability. This study tested whether ecologically similar shrimp from disparate habitats have a comparable ability to identify predators from a range of taxa based on chemical cues. Shrimp from both temperate marine (Palaemon affinis) and tropical freshwater habitats (Caridina typus) exhibited similar behavioural responses, avoiding chemical cues from predatory heterospecifics, showing no response to non-predatory heterospecific cues, and preferring conspecific cues. These chemical cues also affected habitat selection, with structurally complex microhabitats favoured in the presence of predator cues but avoided in the presence of conspecific cues. The ability to differentiate predators from non-predators irrespective of taxa suggests identification might be due to the predator’s diet. An ability to alter behaviour based on vision-independent perception of ambient risk is likely to reduce capture risk while allowing individuals to maximise time spent on essential processes such as foraging.