DOI: 10.5061/dryad.np5hqbzxs
title: Data from: The ontogenetic dietary shift from non-dangerous to dangerous prey in predator-eating predators under capture risk

description: Evaluating the patterns and generality of ontogenetic dietary shifts
 (ODSs) contributes to understanding prey–predator interactions and food
 web dynamics. Numerous studies have focused on predators that target
 distinctively lower trophic‐level organisms. However, the ODS of predators
 that routinely prey on organisms at similar trophic levels (i.e.,
 predator‐eating predators) have been neglected in ODS research. The ODS
 patterns of predator eaters may not fit into conventional frameworks owing
 to constraints of potential capture risk (e.g., deadly counterattack from
 prey) and body size. We aimed to reveal the ODS patterns of predator
 eaters and determine whether the patterns were affected by body size and
 capture risk. Assuming that capture risk is a significant factor in ODS
 patterns, we expected: (1) juvenile araneophagic spiders to forage on
 non‐dangerous prey (insects) and capture larger non‐dangerous prey more
 frequently than dangerous prey (spiders); and (2) as they grow, their prey
 types will shift from non‐dangerous to dangerous prey because larger
 predators will be able to capture dangerous prey as the optimal food. As a
 result of field observations, we revealed that the major ODS pattern in
 these spiders changed from a mixed (both insect and spider) to a
 spider‐dominant diet. The model selection approach showed that this diet
 shift was partly due to predator size, and the relative importance of
 predator size was higher than the life stage per se and almost equal to
 species identity. In these spiders, the body size of spider prey tended to
 be smaller than that of insects when the predators were small, suggesting
 that capture risk may be a critical factor in determining the ODS patterns
 of these predators. Therefore, our study adds to the evidence that the
 capture risk is crucial in comprehensively understanding the mechanisms
 determining ODS patterns in natural systems.
description: The descriptions of the methods used to collect, prepare, and
 analyze the data are in Suzuki, Ikemoto, and Yokoi :  The ontogenetic
 dietary shift from non-dangerous to dangerous prey in predator-eating
 predators under capture risk, published in Ecology and Evolution:
 https://doi.org/10.1002/ece3.9609  
description: # The ontogenetic dietary shift from non-dangerous to dangerous prey in
 predator-eating predators under capture risk
 [https://doi.org/10.5061/dryad.np5hqbzxs](https://doi.org/10.5061/dryad.np5hqbzxs) ## Description of the data and file structure The data includes prey-predator interactions and body size relationships among spiders, insects and four araneophagic spider species. The data was obtained by nocturnal field surveys conducted in the forests of the University of Tsukuba, Tsukuba city, Ibaraki, Japan, from April to October 2018. ### Files and variables **File: Original_Data_Suzuki_Ikemoto_Yokoi_ODS_of_predator_eating_predator.csv** **Description:**  ##### Variables * date: date of the observation * Studyarea: observation site ("A" or "B") * sampleid: serial number of the samples * Species: scientific name of the four predator species (Ariamnes = A. cylindrogaster, Chorizopes = C. nipponicus, Platnickina = P. sterninotata, Rhomphaea = Rhomphaea spp.) * BodyLength: body length of predator (carapace-abdomen) in mm- total length in mm * CarapaceLength: carapace length of predator in mm * Leg1: length of frontal legs (legI) in mm * Leg4: length of hind legs (legIV) in mm * GrowthPhase: growth phase of predator (y: juvenile, am: adult male, af: adult female) * maturity: growth phase of predator (y: juvenile, a: adult) * Position: microhabitat where predation occurred * site: predation or prey-predator interaction occurred in a spider's web (1) or not (0) * Prey: lethal interaction (i.e., predator actually ate prey) occurred (1) or not (0). The latter was omitted in the analyses of the published paper. * lethal: same as the column 10. Lethal interaction (L) or not (N) * preyorder: order name of prey taxa * preytypes: prey type (spider or insect). "insect" here includes some small non-hexapod invertebrates * spider: prey type (spider=1, insect and other microinvertebrates=0) * preybody: body length of prey taxa * preyhead: head (prosoma) length of prey taxa * preyforeleg: length of forelegs (legI) of prey taxa * preyhindleg: length of hind legs (LegIV for spider and legIII for insects) of prey taxa * preyname: specific name of prey taxa * preytrait: trait type (foraging mode) of prey spider * webtype: web type of web-building spider (vert: vertical orb web, horiz: horizontal orb web, line: line web, sheet: sheet web, tangle: tangle web, funnel: funnel web) * preyfamname: family name of prey taxa * preygenus: genus name of prey taxa * allpredlong: total length of predator (sum of Leg1, BodyLength and Leg4). Used as a index of "predator size" in the published paper. * allpreylong: total length of predator (sum of preyforeleg, preybody and preyhindleg). Used as a index of "prey size" in the published paper. For worm-like insects such as lepidoptera larva, only preybody is used for indicating prey size. * note: supplemental notes on the observation Missing data code: NA ## Code/software Software: R ver. 4.0.2 and 4.2.0 software (R Development Core Team, 2020, 2022) Packages: MuMIn (Barton 2022)