Dataset DOI: 10.5061/dryad.1jwstqk74

Description of the data and file structure

We aim to document the potential impacts of condor reintroduction, including heightened competition within the scavenger community and more rapid consumption of carrion. We collected data in sheep pastures in southern Utah and quantified several measures of exploitation and interference competition. Despite consuming the majority of carcasses when present, condors were not frequently detected, even in their preferred habitat. Condors currently have such confined impact that other scavengers likely have little pressure to switch to alternate food sources or habitats.

Files and variables

File: Arrival_orders.csv

Description: This dataset lays out the arrival order of the most common scavenger, by comparing the day and time that the carcass was established with the days and times that scavengers were first detected at that carcass.

Variables

• Carcass: Carcass ID number, unique to each carcass
• Date established: Time and date the carrion was set out with cameras
• First vulture: Time and date, according to trail cameras, when the first vulture was detected at the carcass. Blank cells indicate no vultures were detected.
• Vulture detection time: The difference between the first vulture and the date established, i.e., the number of days it took for the first vulture to be detected by a camera
• First condor: Time and date, according to trail cameras, when the first condor was detected at the carcass. Blank cells indicate no condors were detected.
• Condor detection time: The difference between the first condor and the date established, i.e., the number of days it took for the first condor to be detected by a camera
• First eagle: Time and date, according to trail cameras, when the first eagle was detected at the carcass. Blank cells indicate no eagles were detected.
• Eagle detection time: The difference between the first eagle and the date established, i.e., the number of days it took for the first eagle to be detected by a camera
• First fox: Time and date, according to trail cameras, when the first fox was detected at the carcass. Blank cells indicate no foxes were detected.
• First coyote: Time and date, according to trail cameras, when the first coyote was detected at the carcass. Blank cells indicate no coyotes were detected.
• First raven: Time and date, according to trail cameras, when the first raven was detected at the carcass. Blank cells indicate no ravens were detected.
• First skunk: Time and date, according to trail cameras, when the first skunk was detected at the carcass. Blank cells indicate no skunks were detected.

File: Arrival_rate.csv

Description: This dataset directly compares the difference in visitation rates (visits per hour) of other scavengers before condors arrive, while condors are present at the carcass, and after the last condor has left.

Variables

• Carcass: Carcass ID, unique to each carcass. Condors arrived and left as a group, and two groups of condors arrived at carcass 22, which is why it is repeated. Otherwise, condors only arrived and fed on any carcass once.
• First condor arrival: The day and time that the first condor arrived, as recorded by trail cameras.
• Last condor leave: The day and time that the last condor departed, as recorded by trail cameras.
• Carcass established: The day and time that a carcass was set out with cameras.
• Days until condor: The difference in days between carcass establishment and condor arrival.
• Hours until condor: The difference in hours between carcass establishment and condor arrival.
• Number of condors during: The total number of condors present during the feeding bout. Condors are all individually marked and were also all present simultaneously.
• Number of vulture visits before: The number of turkey vulture visits between carcass establishment and condor arrival. Visits were classified as any new individual landing at the carcass or a detection of a turkey vulture after none had been recorded for 15 minutes.
• Rate vulture visit before: Visit rate of turkey vultures before condors arrived, in visits per hour. The number of turkey vulture visits before is divided by the number of hours until the condor.
• Number of eagle visits before: The number of golden eagle visits between carcass establishment and condor arrival. Visits were classified as any new individual landing at the carcass or a detection of a golden eagle after none had been recorded for 15 minutes.
• Rate eagle visit before: Visit rate of golden eagles before condors arrived, in visits per hour. Number of golden eagle visits before is divided by the number of hours until the condor.
• Number of fox visits before: The number of fox visits between carcass establishment and condor arrival.
• Number of skunks before: The number of skunk visits between carcass establishment and condor arrival.
• Last condor leave: The day and time that the last condor departed the carcass.
• End obs time: The last time and day of footage. Usually, when the camera was pulled, but occasionally when the SD card filled up or batteries died.
• Number vulture visits after: The number of turkey vulture visits between condor departure and the last video from the camera. Visits were classified as any new individual landing at the carcass or a detection of a turkey vulture after none had been recorded for 15 minutes.
• Rate vulture visit after: Visit rate of turkey vultures after condors departed, in visits per hour.
• Number of eagle visits after: The number of golden eagle visits between the condor departure and the last video from the camera. Visits were classified as any new individual landing at the carcass or a detection of a golden eagle after none had been recorded for 15 minutes.
• Rate eagle visit after: Visit rate of golden eagles after condors departed, in visits per hour.
• Number of fox visits after: The number of fox visits between the condor departure and the last video from the camera.
• Number of skunk visits after: The number of skunk visits between the condor departure and the last video from the camera.

File: Carcasses_cleaned.csv

Description: Information on all carcasses set out, including condor visitation numbers and initial weight of the carcass.

Variables

• Carcass_ID: A unique number assigned to each carcass, ascending consecutively
• Number of condors that visited the carcass: The total number of individual condors that visited the carcass, using unique markers on the condors. NA designates missing data, such as when the learner sign shows condors were present, but cameras failed, so we could not assess the number of condors.
• All_condor_visit: A binary variable representing whether condors were present, absent, or unknown (designated by an NA), using both feeding sign and trail camera footage.
• Initial_weight_kg: The weight of the carrion when it was set out, in kg. Large carcasses were estimated from published averages; carcasses below 25 kg were weighed with a scale.

File: Condor_facilitation.csv

Description: This dataset contains information on condor arrivals at carcasses, carrion accessibility, and amounts of carrion remaining.

Variables

• Carcass: Unique number identifying which carcass the information is tied to.
• Number of condors: Total number of individual condors that arrived during a condor group's visit, using unique patagial tags
• Visit number of condor group: The visit number of the focal condor group, when only counting condor groups that had already arrived (so the majority of visits are the first condor group to visit a carcass)
• First condor arrival: The time and day that the first condor arrived
• Last condor leave: The time and day that the last condor leaves
• Carcass state arrival: The size of openings in the carcass when the first condor arrives
• Carcass percent consumed arrival: A visually estimated percent, from the trail camera recording, of the carrion consumed just before the first condor arrived
• Carcass state leaving: The size of openings in the carcass when the last condor leaves
• Carcass percent consumed leaving: A visually estimated percent, using trail camera recordings, of the carrion consumed after the last condor leaves
• Percent eaten during condor: The difference between carcass percent consumed leaving and carcass percent consumed arrival, or the percent of the carcass consumed while condors were attending the carcass.
• Duration condor group: The difference between the first condor arrival and last condor leave, or the duration that the condors were present at the carcass.

File: Displacements_summary.csv

Description: A table of total displacements recorded between species

Variables

• columns: species displaced
• rows: species displacing
• values: the number of times a displacement was recorded

File: FeedingTimeSp.csv

Description: Results from a Kruskal-Wallis test on feeding times at carcasses between scavenger species

Variables

• Group.1: Species
• mean: the mean feeding time across visits, in seconds
• x: the standard deviation of feeding time across visits, in seconds

File: TukeyDisplacementRate.csv

Description: The results of a Tukey's honest significant difference test for displacement rate (displacements per hour) across different scavenger species

Variables

• diff: the difference in means of displacement rate between the pair of species
• lwr: the lower bound of the confidence interval, on the mean difference
• upr: the upper bound of the confidence interval, on the mean difference
• p adj: the adjusted p value of the difference in mean displacement rate from the pairing

File: Displacements.csv

Description: A long-form version of displacements_summary, with each species and context for the displacement (ie, carcass, group sizes for each species)

Variables

• Carcass: a unique number given to each established carcass in ascending order. Carcass numbers may be skipped (if no displacements were recorded) or repeated (if several displacements occurred)
• Displacer_species: The speciesthat  successfully displaces another individual during the interaction
• Displacee_species: The species displaced by another individual during the interaction
• Condor_num: The number of condors attending the carcass when the displacement occurred
• Eagle_num: The number of eagles attending the carcass when the displacement occurred
• Vulture_num: The number of vultures attending the carcass when the displacement occurred

File: VisitTimeDifference.csv

Description: A summary table showing the mean and standard deviation of the duration of a visit across scavenger species

Variables

• Group.1: The scavenger species
• mean: The mean, in seconds, that an individual visited a carcass
• x: The standard deviation, in seconds, that an individual visited a carcass

File: Visits_cleaned_prop.csv

Description: Information on each recorded visit, including carcass ID, scavenger species, and length of time spent, total and actively foraging

Variables

• ID: A unique ascending number for each visit. The dataset was restricted to visits lasting longer than 60 seconds of known behavior within a frame, so some visit IDs have already been removed.
• Visit_per_species: An ascending number for a focal species at a carcass.
• Carcass: A unique number given to each carcass. Carcass numbers may be skipped or repeated in this dataset if no visits existed and passed the initial filters, or if multiple visits did, respectively.
• Species: The scavenger species that visited the carcass
• Eaten_arrival: A visually estimated percent of the carrion eaten when the scavenger first arrived
• Eaten_leaving: A visually estimated percent of the carrion eaten at the end of the scavenger's visit
• Feeding_time: The number, in seconds, that the scavenger was actively feeding on the carcass (head down, touching carrion)
• Number_of_displacements: The total number of displacements caused by the scavenger during the focal visit
• Time_known_behavior: The total number of seconds that we have recorded behaviors during a visit. This is the sum of feeding, vigilance, and other behaviors such as moving or preening.
• Time_total_behavior: The total number of seconds that the visit lasted. This includes "known behavior" time as well as time where behavior is unknown, such as when the individual is briefly off-screen, behind the carcass, or too far away to determine behavior accurately.
• GUD: Giving-up density. The percentage of the carrion eaten during a visit, if the individual does not leave due to a displacement by another individual
• Feeding_prop: The proportion of time spent feeding during a visit. Feeding time is divided by the total known behavior.
• Max_group: The maximum group size, including all other individuals of all species from either arrival or departure.

File: Ornithology-25-012.R

Description: The R file that includes all the code for this analysis. The code is organized within headers but is otherwise minimally commented upon.

Code/software

R (vers 4.2.1)

R packages:

tidyverse (vers 1.3.2)

lubridate (vers 1.9.0)

DHARMa (vers 0.4.6)

glmmTMB (vers 1.1.8)

pgirmess (vers. 2.0.2)

ggeffects (vers. 1.3.4)

ggplot2 (vers 3.4.4)