Olfactory eavesdropping: The odor of feathers is detectable to mammalian predators and competitors

Abstract

The role of olfactory eavesdropping in interactions between mammalian predator and prey species is well established. Bird plumage can be odorous and consequently nest predators could use odor to identify and locate avian prey, and nest competitors could use odor to assess occupancy of nest cavities by birds. However, despite extensive research on avian nest predation and competition, the costs of olfactory eavesdropping on plumage odor by nest predators or competitors remain largely unknown. We used two experiments to investigate whether feather odor is detected by marsupial species which are competitors for nest hollows and predators of eggs and nestlings of crimson rosellas, Platycercus elegans. In the first experiment, odor presentation at nest boxes utilized by ringtail possums (Pseudocheirus peregrinus) and rosellas showed that the latency of possums to enter the nest was shorter when crimson rosella odor was present compared to the controls. In the second experiment, carried out away from nest hollows, brushtail possums (Trichosurus vulpecula) discriminated odors of two predators (dingo, Canis lupus dingo, and cat, Felis catus) from crimson rosella and control odors; however, they did not discriminate between crimson rosella odor and a control. We show that marsupials may use feather odor cues to assess nest hollow status, information which could aid their detection of avian prey or their vigilance at nest hollows (for which they compete with parrots). To our knowledge, our study is the first to show that wild mammalian predators and competitors of birds respond to plumage odor at nests and suggest that odor signaling may have hitherto unrecognized costs for birds. K E Y W O R D Savian olfaction, competition, nest, predation

Experimentally broken faecal sacs affect nest bacterial environment, development and survival of spotless starling nestlings

“…Petit et al () deposited experimental faeces that predators could visualize near focal artificial nests and attracted predators. Rubio et al () performed a similar experiment in inactive nests of a grown nester, but in this case, the presence of faecal sacs did not attract predators. Moreover, Ibáñez‐Álamo et al (b) hided experimental faecal sacs to terrestrial predators in common blackbird Turdus merula active nests, which did not increase the probability of nest predation, suggesting that Petit et al ()'s results were due to visual cues of faecal sacs.…”

“…Recently, the importance of volatiles produced by symbiotic bacteria have been stressed in scenarios of social communication (Theis et al , Ezenwa and Williams , Leclaire et al ), predator–prey, or parasite–host interactions (Bucher , Gow et al , Schulte et al ). Prey might for instance use predator odours in antipredator behaviour (Heise‐Pavlov ), or predators might use volatiles from symbiotic bacteria of prey as clues to detect their victims (Fogarty et al , Mihailova et al ). Previous studies have explored the possibility that faecal sacs attract potential predators and/or parasites, but did not find support for the hypothesis.…”

“…Thus, control and experimental nests with 14 d old starlings are typically full of excrements and with similar bacterial loads of nest lining material (see Results). Consequently, nest bacterial loads at this stage is too high (Devaynes et al ) and, thus, are not a good proxy of nest bacterial environment experience by developing nestlings in experimental and control nests. Looking for a better proxy of bacterial environment experienced by nestlings during growing, in the breeding season, we also sampled nest material on day 12, before parents stopped removing nestling faeces from nest‐boxes, in a reduced number of nests (: n = 128; : n = 21).…”

“…In birds, pathogenic effects of bacteria have mainly been explored in poultry and, more recently, also in wild birds (Benskin et al ). Negative effects in terms of survival or viability have been detected for embryos (Soler et al a, Peralta‐Sánchez et al ), nestlings, and adult wild birds (Benskin et al ). All these negative effects strongly select for defensive strategies and barriers against bacterial infections, such as particular immune responses (Soler et al ), antimicrobial secretions (Soler et al , 2010, 2012a, Møller et al , Ruiz‐Rodríguez et al , Martín‐Vivaldi et al ), the use of aromatic plants with antimicrobial capabilities as nest materials (Gwinner and Berger 2005, Mennerat et al , Ruiz‐Castellano et al ), or nest sanitation behaviours to prevent or limit bacterial growth (Ibáñez‐Álamo et al ).…”

Egg ejection cost can limit defence strategies against brood parasitism

“…nocturnal predators are more likely to use olfactory (Mihailova, Berg, Buchanan, & Bennett, 2018;Whelan, Dilge, Robson, Hallyn, & Dilge, 1994), thermal (Stake, Thompson, Faaborg, & Burhans, 2005;Weatherhead & Blouin-Demers, 2004) and auditory cues (Briskie, Martin, & Martin, 1999;Halupka, 1998;Rice, 1982) to find nests.…”