DOI: 10.5061/dryad.ghx3ffbvc
title: Data from: Hunting behavior and feeding ecology of Mojave Rattlesnakes (Crotalus scutulatus), Prairie Rattlesnakes (C. viridis), and their hybrids in southwestern New Mexico

description: Predators must contend with numerous challenges to successfully find and
 subjugate prey. Complex traits related to hunting are partially controlled
 by a large number of co-evolved genes which may be disrupted in hybrids.
 Accordingly, research on the feeding ecology of animals in hybrid zones
 has shown that hybrids sometimes exhibit transgressive or novel behaviors,
 yet for many taxa empirical studies of predation and diet across hybrid
 zones is lacking. We undertook the first such field study for a hybrid
 zone between two snake species, the Mojave Rattlesnake (Crotalus
 scutulatus) and Prairie Rattlesnake (C. viridis). Specifically, we
 leveraged established field methods to quantify hunting behaviors of
 animals, their prey communities, and diet of individuals across the hybrid
 zone in southwestern New Mexico, USA. We found that, even though hybrids
 had significantly lower body condition indices than snakes from either
 parental lineage, hybrids were generally similar to non-hybrids in hunting
 behavior, prey encounter rates, and predatory attack and success. We also
 found that, compared to C. scutulatus, C. viridis was significantly more
 active while hunting at night and abandoned ambush sites earlier in the
 morning, and hybrids tended to be more viridis-like in this respect. Prey
 availability was similar across the study sites, including within the
 hybrid zone, with Kangaroo Rats (Dipodomys spp.) as the most common small
 mammal both in habitat surveys and frequency of encounters with hunting
 rattlesnakes. Analysis of prey remains in stomachs and feces also showed
 broad similarity in diets, with all snakes preying primarily on small
 mammals and secondarily on lizards. Taken together, our results suggest
 that the significantly lower body condition of hybrids does not appear to
 be driven by differences in their hunting behavior or diet, and may
 instead relate to metabolic efficiency or other physiological traits we
 have not yet identified.
description: # Hunting behavior and feeding ecology of Mojave Rattlesnakes (Crotalus
 scutulatus), Prairie Rattlesnakes (C. viridis), and their hybrids in
 southwestern New Mexico This dataset includes final VCF alignment file
 used for hybrid index analysis, Scaled Mass Index (SMI), hunting behavior,
 hunting frequency, prey encounter types and rates, toad and lizard
 presence/absence, and small mammal trapping data used in order to quantify
 the hunting behaviors and diet of snakes dispersed across a hybrid zone
 between Mojave (Crotalus scutulatus) and Prairie (C. viridis)
 Rattlesnakes. The VCF alignment data were collected via raw sequence reads
 from DNA extractions from blood stored in lysis buffer. SMI was calculated
 from mass and snout\*vent length measurements performed on the snakes. The
 hunting behavior and frequency, and prey encounters were collected via a
 combination of field telemetry and videography. Toad and lizard
 presence/absence data were collected via visual encounter surveys. Small
 mammal trapping data was collected via Sherman trapping lines. Generally,
 even though hybrids were in poorer body condition than snakes from either
 parental lineage, all snakes displayed similar hunting behaviors, and
 rates of predatory success. ## Description of the data and file structure
 VCF alignment: This file contains the biallelic variants for all
 individuals used in the behavioral analyses. For all data: * NA = data was
 not collected due to the data being not applicable (ex., NA for strike
 success since the snake never struck at a prey item, NAs in the
 small\_mammal\_trapping data when the trap did not capture a small mammal,
 or NA for HI\_viridis\_proportion due to sample failure) snake\_SMI: *
 snake = the ID of the individual * HI\_scutulatus\_proportion = 1 minus
 the HI\_viridis\_proportion * HI\_viridis\_proportion = Hybrid index based
 on the VCF alignment * genetic\_species = which lineage the individual
 belonged to based on its hybrid index and the 0.05 and 0.95 cutoffs for
 parental groupings. * CRSC = Crotalus scutulatus * SCVI = Hybrid * CRVI =
 Crotalus viridis * SMI = Scaled Mass Index calculated based on Peig and
 Green 2009. hunting\_behavior: * ID = the ID of the individual * n = the
 number of hunting nights the snake was filmed for * species = the putative
 grouping that the snake was assigned to based on site of capture and
 morphology * CRSC = Crotalus scutulatus * SCVI = Hybrid * CRVI = Crotalus
 viridis * sex = sex of the snake * f = female * m = male * mass = mass of
 the snake to the nearest gram * SVL = Snout Vent Length of the snake to
 the nearest millimeter * SMI = Scaled Mass Index calculated based on Peig
 and Green 2009 * probe\_freq = number of probes per minute of hunting *
 night\_probe\_freq = number of probes per minute of hunting at night *
 day\_probe\_freq = number of probes per minute of hunting after sunrise *
 gape\_freq = number of gapes per minute of hunting * night\_gape\_freq =
 number of gapes per minute of hunting at night * day\_gape\_freq = number
 of gapes per minute of hunting during the day * prey\_freq = number of
 encountered prey per minute by the snake while hunting * strike\_freq =
 number of strikes the snake elicited towards encountered prey per total
 prey encounters * succ\_freq = number of strikes that contacted the prey
 item per number of strikes the snake elicited towards encountered prey *
 aftr\_rise = number of minutes the snake spent hunting prior to sunrise *
 before\_down = number of minutes the snake spent hunting prior to sunset *
 ave\_abandontime = The average time of day in seconds that the snake
 stopped hunting * trans\_gape\_freq = Zero inflated transformation
 (Smithson and Verkuilen 2005) of gape\_freq in order to perform a beta
 regressiontrans\_day\_probe\_freq = Zero inflated transformation (Smithson
 and Verkuilen 2005) of probe\_freq in order to perform a beta regression *
 trans\_night\_gape\_freq = Zero inflated transformation (Smithson and
 Verkuilen 2005) of night\_gape\_freq in order to perform a beta regression
 * trans\_day\_gape\_freq = Zero inflated transformation (Smithson and
 Verkuilen 2005) of day\_gape\_freq in order to perform a beta regression *
 trans\_prey\_freq = Zero inflated transformation (Smithson and Verkuilen
 2005) of prey\_freq in order to perform a beta regression *
 trans\_strike\_freq = Zero inflated transformation (Smithson and Verkuilen
 2005) of strike\_freq in order to perform a beta regression *
 trans\_succ\_freq = Zero inflated transformation (Smithson and Verkuilen
 2005) of succ\_freq in order to perform a beta regression *
 HI\_scutulatus\_proportion = 1 HI\_viridis\_proportion *
 HI\_viridis\_proportion = Hybrid index based on the VCF alignment *
 genetic\_species = which lineage the individual belonged to based on its
 hybrid index and the 0.05 and 0.95 cutoffs for parental groupings. * CRSC
 = Crotalus scutulatus * SCVI = Hybrid * CRVI = Crotalus viridis
 hunting\_frequency: * ID = the ID of the individual * nights\_tracked =
 the number of nights that the snake was located via field telemetry *
 nights\_hunted = the number of nights that the snake was located via field
 telemetry and it was on the surface in an ambush posture or was found
 eating a food item * hunt\_freq = nights\_hunted divided by
 nights\_tracked * species = the putative grouping that the snake was
 assigned to based on site of capture and morphology * CRSC = Crotalus
 scutulatus * SCVI = Hybrid * CRVI = Crotalus viridis * sex = sex of the
 snake * f = female * m = male * mass = mass of the snake to the nearest
 gram * SVL = Snout Vent Length of the snake to the nearest millimeter *
 SMI = Scaled Mass Index calculated based on Peig and Green 2009 *
 HI\_scutulatus\_proportion = 1 HI\_viridis\_proportion *
 HI\_viridis\_proportion = Hybrid index based on the VCF alignment *
 genetic\_species = which lineage the individual belonged to based on its
 hybrid index and the 0.05 and 0.95 cutoffs for parental groupings. * CRSC
 = Crotalus scutulatus * SCVI = Hybrid * CRVI = Crotalus viridis
 prey\_encounter: * snake = the ID of the individual * n = the number of
 hunting nights the snake was filmed for * sex = sex of the snake * f =
 female * m = male * mass = mass of the snake to the nearest gram * SVL =
 Snout Vent Length of the snake to the nearest millimeter * SMI = Scaled
 Mass Index calculated based on Peig and Green 2009 * genetic\_species =
 which lineage the individual belonged to based on its hybrid index and the
 0.05 and 0.95 cutoffs for parental groupings. * CRSC = Crotalus scutulatus
 * SCVI = Hybrid * CRVI = Crotalus viridis * Tambushtime.all = time in
 minutes that the snake spent hunting * encounters = the number of prey
 encounters that the snake had while hunting * prey.type = the type of prey
 that encountered the snake while it was hunting * anuran = A frog or a
 toad * bird = A non predatory bird (i.e., not a raptor or roadrunner) *
 Dipodomys = A small mammal that belongs to the genus Dipodomys * lizard =
 a lizard (squamata) * non\_Dipodomys = a small mammal that does not belong
 to the genus Dipodomys * freqs = encounters divided by Tambushtime.all
 toad\_lizard\_P\_A * site = the general location that the toad or lizard
 species was found in * CRSC = Mojave Site (Southwest of Zone) * SCVI =
 Hybrid Zone * CRVI = Prairie Site (Northeast of Zone) * year = the year
 the sites were sampled for the presence/absence of toad and lizard species
 * dom\_veg = a sub class of the site, breaking it up by the dominant
 vegetation type * ANCO through UTST = the species code for each species
 found at least at one of the sites * ANCO = Anaxyrus cognatus * ANDE =
 Anaxyrus debilis * ANPU = Anaxyrus punctatus * ANWO = Anaxyrus woodhouseii
 * SCCO = Scaphiopus couchii * SPMU = Spea multiplicate * ASspp =
 Aspidoscelis spp. * COVA = Coleonyx variegatus * GAWI = Gambelia
 wislizenii * HOEL = Holbrookia elegans * PHCO = Phrynosoma cornutum * PHMO
 = Phrynosoma modestum * SCspp = Sceloporus spp. * UTST = Uta stansburiana
 small\_mammal\_trapping * year = the year that the small mammal trapping
 occurred * population = the general location that the trap line was placed
 in * CRSC = Mojave Site (Southwest of Zone) * SCVI = Hybrid Zone * CRVI =
 Prairie Site (Northeast of Zone) * habitat = a sub class of the
 population, breaking it up by the dominant vegetation type * trap line =
 the trap line for that specific population and habitat’s line * trap
 number = the number of the trap in the trap line * easting = the easting
 of the pair of traps place in the trap line (zone 12) * northing = the
 northing of the pair of traps place in the trap line (zone 12) * moon
 phase = the percentage of the moons surface that is visible that trap
 night, positive number indicate a waxing moon, negative numbers indicate a
 waning moon * trap night = the date (mm/dd/yyyy) of the night that the
 traps were set on * time open = the time of day (hh:mm) that the trap line
 was set * midnight = midnight (00:00) used a reference point * time close
 = the time of day (hh:mm) that the trap line was closed * successful = was
 the trap successful in trapping a small mammal between the time open and
 time close * species = the four character code (first two letters of the
 genus and first two letters of the species names) of the species of small
 mammal caught in the trap * ID = the species code followed by the number
 of the ear tag used to tag the animal * recap = was this individual
 recaptured before? * sex = sex of the snake * f = female * m = male * j =
 juvenile * mass = the mass of the individual to the nearest 0.1 g * SVL =
 Snout-Vent Length of the small mammal to the nearest millimeter * tail
 length = Tail Length of the small mammal to the nearest millimeter *
 hindfoot length = Hindfoot Length of the small mammal to the nearest
 millimeter * hindfoot count = the number of digits on the right hindfoot
 of the small mammal * condition = outward appearance of the small mammal *
 ear clip/tag = the number of the ear tag that was used to tag the
 individual * trap unavailable = was the trap rendered unavailable for
 whatever reason (covered in hundreds of ants, smashed by a cow, etc.) ##
 Sharing/Access information For additional ways to access this data and
 inquires about it, feel free to contact the corresponding author of the
 paper, Dr. Dylan Maag ## Software The VCF alignment data file can be
 accessed by software such as vcftools or bcftools.