Precise cache detection by olfaction in a scatter-hoarder bird

Molina‐Morales, Mercedes; Castro, Jorge; Albaladejo, Gonzalo; Parejo, Deseada

doi:10.1016/j.anbehav.2020.07.002

Cited by 10 publications

(6 citation statements)

References 51 publications

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“…Birds commonly depredate nests during the day (Reidy & Thompson, 2012) and rely mainly on visual cues, but may also use olfactory cues (e.g. Buitron & Nuechterlein, 1985; Molina‐Morales et al ., 2020). A more accurate proxy of vulnerability to olfactorily searching nest predators would be, for example, the incidence of such predators weighted by the likelihood of nest detection by olfaction, but such a measure was impossible to obtain for the species and populations included in our analyses.…”

Section: Discussionmentioning

confidence: 99%

Olfactory camouflage and communication in birds

Grieves

Gilles

Cuthill³

et al. 2022

Biological Reviews

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Smell is a sensory modality that is rarely considered in birds, but evidence is mounting that olfaction is an important aspect of avian behaviour and ecology. The uropygial gland produces an odoriferous secretion (preen oil) that can differ seasonally and between the sexes. These differences are hypothesized to function in olfactory camouflage, i.e. minimizing detection by nest predators (olfactory crypsis hypothesis), and/or intraspecific olfactory communication, particularly during breeding (sex semiochemical hypothesis). However, evidence for seasonal and sex differences in preen oil is mixed, with some studies finding differences and others not, and direct evidence for the putative function(s) of seasonal variation and sex differences in preen oil remains limited. We conducted a systematic review of the evidence for such changes in preen oil chemical composition, finding seasonal differences in 95% of species (57/60 species in 35 studies) and sex differences in 47% of species (28/59 species in 46 studies). We then conducted phylogenetic comparative analyses using data from 59 bird species to evaluate evidence for both the olfactory crypsis and sex semiochemical hypotheses. Seasonal differences were more likely in the incubating than non‐incubating sex in ground‐nesting species, but were equally likely regardless of incubation strategy in non‐ground‐nesting species. This result supports the olfactory crypsis hypothesis, if ground nesters are more vulnerable to olfactorily searching predators than non‐ground nesters. Sex differences were more likely in species with uniparental than biparental incubation and during breeding than non‐breeding, consistent with both the olfactory crypsis and sex semiochemical hypotheses. At present, the data do not allow us to disentangle these two hypotheses, but we provide recommendations that will enable researchers to do so.

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Section: Discussionmentioning

confidence: 99%

Olfactory camouflage and communication in birds

Grieves

Gilles

Cuthill³

et al. 2022

Biological Reviews

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“…Magpies arrived at the study site in 2002 as part of a process of local expansion within their regional distribution area, and are currently a common resident bird that acts as scatter hoarder of walnuts. Moreover, the magpie is the only scatter‐hoarder bird that disperses nuts in the area (Castro et al, 2017; Molina‐Morales et al, 2019) and the only bird that has been recorded (Molina‐Morales et al, 2020) or observed (JC and MMM personal observation) retrieving nuts from caches, providing an ideal system to study fine‐grained details of the interaction between a scatter hoarder and a nut‐producing tree. The common walnut ( Junglans regia ) is not a native tree in the area, but it is traditionally grown on farms, possibly since Roman times, as scattered trees close to houses to provide families with nuts (Castro et al, 2017).…”

Section: Methodsmentioning

confidence: 99%

Linking animal behaviour and tree recruitment: Caching decisions by a scatter‐hoarder corvid determine seed fate in a Mediterranean agroforestry system

et al. 2022

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1. Seed dispersal by scatter-hoarder corvids is key for the establishment of important tree species from the Holarctic region such as the walnut (Juglans regia). However, the factors that drive animal decisions to cache seeds in specific locations and the consequences of these decisions on seed fate are poorly understood.2. We experimentally created four distinct, replicated habitat types in a Mediterranean agricultural landscape where the Eurasian magpie (Pica pica) is a common scatter hoarder: soft bare soil; compacted bare soil; compacted soil with a dense herbaceous cover; and soft linear bare soil made up of the irrigation furrows that separated the rest of the treatments. We also experimentally placed visual landmarks (stones, sticks and bunches of dry plants) to test if magpies use them to place seed caches. Walnut dispersal from feeders to the habitats was monitored by radiotracking and camera traps.3. A sowing experiment simulating natural caches tested the effect of caching type on seed germination and seedling emergence. Seed mass was controlled for the dispersal and sowing experiments. 4. Magpies selected the two habitats with soft soil, and avoided the one with compacted soil, to cache nuts. Seed mass did not affect dispersal distance, germination or emergence; however, heavier seeds were cached more often under litter and in the habitat with herbaceous cover, whereas lighter seeds were more often buried in the soft bare soil habitat. Seed burial under soil or litter determined

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“…Therefore, the effectiveness of egg camouflage or size against depredation depends on predator species and their different search tactics and sensory inputs. While mammalian predators presumably rely on olfactory stimuli, avian predators are thought to be mainly visually oriented, although some of them, like corvids, might also use olfactory cues (Molina-Morales et al, 2020). Therefore, depredation by predators using olfactory cues may not be affected by vegetation height while nest depredation risk would decrease in tall vegetation as avian predators rely on visual cues (Clark et al, 1991).…”

Section: Introductionmentioning

confidence: 99%