DOI: 10.5061/dryad.47d7wm3s2
title: Does a lack of juveniles indicate a threat? Understanding body size distributions in a group of long-lived vertebrates

description: This data set contains size and/or sex data from 41,021 freshwater turtles
 from 38 species and 428 populations located in parts of Australia both
 with and without introduced foxes, as well as populations in the United
 States of America, which naturally have raccoons (Procyon lotor), foxes,
 and other nest predators. The goal was to examine population-level body
 size distributions to establish a baseline for “typical” turtle
 populations and test whether populations that are exposed to introduced
 foxes have proportionately fewer juveniles compared to both AU populations
 that lack introduced foxes and USA populations that are naturally exposed
 to nest predators. We additionally conducted analyses on the biases of
 trapping methods, effects of sample size, and effects of water body type.
 This data set was assembled by pooling the data from numerous researchers.
description: # Does a lack of juveniles indicate a threat? Understanding body size
 distributions in a group of long-lived vertebrates Dataset DOI:
 [10.5061/dryad.47d7wm3s2](10.5061/dryad.47d7wm3s2) ## Description of the
 data and file structure These data sets were collected by multiple
 researchers conducting field work on freshwater turtles. They have been
 combined for this study. ### Files and variables #### File: full.data.csv
 **Description:** This contains the primary data used for most analyses.
 Each individual turtle was only included upon first capture. Therefore, no
 recaptures were included. These data have not been subset to populations
 with at least 50 individuals. See original paper ("**Does a lack of
 juveniles indicate a threat? Understanding body size distributions in a
 group of long-lived vertebrates**" [Journal of Animal Ecology]) for
 additional information. Throughout, NA indicates that the data point was
 not collected. ##### Variables * country.fox: Codes for country and
 whether foxes were present * AU.fox = Australia, foxes present * AU =
 Australia, foxes are rare or absent * USA = United States of America,
 foxes present * region: * Broad geographic region. River drainage in AU
 and the states in the USA (sometimes neighboring states were combined) *
 site: * Specific study site. Sometimes included multiple neighboring
 bodies of water among which turtles could move (i.e., each site represents
 a population per species). Sites are dummy-coded to protect species.
 Additional details (such as the years of data at a given site) are
 available in Supplemental Information 2 of "Does a lack of juveniles
 indicate a threat? Understanding body size distributions in a group of
 long-lived vertebrates" (Journal of Animal Ecology) *
 water.body.type: Broad categories used to group bodies of water by their
 habitat type. Due to the large number of sites used in this study (and the
 frequent presence of multiple proximate bodies of water), these categories
 are necessarily crude. * river = Flowing bodies of water that generally
 contain water year-round (contrast with intermittent). * intermittent =
 Seasonal creeks and rivers that frequently dried to disconnected water
 holes (e.g., many desert systems). * wetland = Floodplain wetlands. Lentic
 oxbows and other side channels are directly connected to rivers at least
 seasonally. Sometimes vegetated. * lakes = Lakes and ponds. Lentic bodies
 of water that were disconnected from main rivers (with the exception of
 reservoirs formed by damming rivers), including farm ponds and heavily
 vegetated areas such as beaver ponds, swamps, and marshes. * species:
 scientific name of study species * sex.age: Sex or age category * m =
 adult male * f = adult female * j = juvenile (could not be sexed) * a =
 adult (could not be sexed) * scl: Straight Carapace Length (mm) *
 capture.method: trapping method used to capture individuals * hand =
 Turtles captured by a means other than a trap or snorkelling (e.g., dip
 netting, captured crossing a road, grabbed while wading through a wetland,
 etc.) * Snorkel = Using a mask and snorkel to free-dive for turtles
 (a.k.a., “water goggling”) * crawfish.minnow.net = Small, fine-mesh traps
 designed for capturing bait such as crawfish and minnows, typically placed
 in very shallow water (e.g., collapsible spring traps such as those made
 by Promar® and Drasry®). * cathedral.net = Any form of tall net with
 openings near the bottom attached to a large “snorkel” section to allow
 turtles to breathe. These traps were typically either upheld by floats or
 suspended from structures such as branches. “Cathedral nets” included both
 traps that were simple crab pots attached to a vertical column of mesh and
 more complicated traps that included a second vertical funnel and/or
 telescoping rings forming a vertical column. * hoop.net = Traps with
 circular, square, or diamond-shaped mesh (typically 2.54 x 2.54 cm or
 smaller) supported by circular or D-shaped rings (typically 0.5–1 m
 diameter) containing one or two funnel-shaped horizontal openings (a.k.a.
 drum nets; Lagler, 1943, 1960). Hoop nets were placed horizontally in
 water that was typically shallow enough to provide access to air. We
 excluded all nets with a “wing” or “lead” from this category (see Fyke
 nets). Hoop nets generally included only one throat, but sometimes nets
 with two throats in a series were used. Hoop nets were generally, but not
 always, baited * fyke.net = Similar to hoop nets but contained at least
 one “wing” or “lead” (i.e., a large wall of vertical mesh [aquatic drift
 fence] that extended from the trap and guided animals into the mouth of
 the trap [Vogt, 1980]. Both traps with a single lead and traps with two
 leads oriented in a “Y” were included as “fyke nets” (sometimes two fykes
 were placed at opposite ends of the leads). Fyke nets generally, but not
 always, include at least two throats in series. Fyke nets were generally
 (but not always) baited. * crab.pot = Low, flat traps with multiple
 openings leading into a single rectangular or cylindrical compartment.
 These were often fully submerged and checked regularly. * other.unknown =
 trap type was not originally described clearly enough to assign it to one
 of these categories * unknown.trap = trap type unknown #### File:
 methods.data.csv **Description:** Unlike full.data.csv, this file contains
 the first capture per individual, per site, *per capture.method*. Thus,
 individuals may be in the data set multiple times if they were captured by
 multiple methods. This data set was used for the pairwise comparisons of
 methods. ##### Variables All variables are identical to those in
 full.data.csv ## Code/software All analyses were conducted in R. See
 "**Does a lack of juveniles indicate a threat? Understanding body
 size distributions in a group of long-lived vertebrates**" (Journal
 of Animal Ecology) for analysis details.