DOI: 10.5061/dryad.41ns1rnnn
title: Data from: Effects of resource availability and interspecific interactions on Arctic and red foxes' winter use of ungulate carrion in the Fennoscandian low-Arctic tundra

description: In the Arctic tundra, predators face recurrent periods of food scarcity
 and often turn to ungulate carcasses as an alternative food source. As
 important and localized resource patches, carrion promotes co-occurrence
 of different individuals, and its use by predators is likely to be
 affected by interspecific competition. We studied how interspecific
 competition and resource availability impact winter use of carrion by
 Arctic and red foxes in low Arctic Fennoscandia. We predicted that
 presence of red foxes limits Arctic foxes’ use of carrion, and that
 competition depends on the availability of other resources. We monitored
 Arctic and red fox presence at supplied carrion using camera traps. From
 2006 to 2021, between 16 and 20 cameras were active for two months in late
 winter (288 camera-winters). Using a multi-species dynamic occupancy model
 at a week-to-week scale, we evaluated use of carrion by foxes while
 accounting for the presence of competitors, rodent availability and
 supplemental feeding provided to Arctic foxes. Competition affected
 carrion use by increasing both species’ probability to leave occupied
 carcasses sites between consecutive weeks. This increase was similar for
 the two species, suggesting symmetrical avoidance. Increased rodent
 abundance was associated with a higher probability of colonizing carrion
 sites for both species. For Arctic foxes, however, this increase was only
 observed at carcasses unoccupied by red foxes, showing greater avoidance
 when alternative preys are available. Supplementary feeding increased
 Arctic foxes' carrion use, regardless of red fox presence. Contrary
 to expectations, we did not find strong signs of asymmetric competition
 for carrion in winter, which suggests that interactions for resources at a
 short time scale are not necessarily aligned with interactions at the
 scale of the population. In addition, we found that competition for
 carcasses depends on the availability of other resources, suggesting that
 interactions between predators depend on the ecological context.
description: COAT is a project aiming to give robust documentation and
 predictions on climate change impacts on biodiversity, natural resources
 and ecosystem processes in the Norwegian Arctic, as a basis for management
 interventions and adaptations. This dataset is obtained from a camera trap
 survey conducted on Varanger Peninsula, Northern Norway between 2006 and
 2021. Each year, between 16 and 20 camera traps were
 active taking photos every 10 min for two months in late winter. We used
 several camera models with different fields of view (Camtrak; Reconyx
 Rapidfire, Hyperfire and Hyperfire 2). The cameras were painted in white,
 modified to have a flat front keeping snow from accumulating and powered
 by external batteries placed in a waterproof contained under the snow.
 Pictures were visually inspected and presence of species was recorded.
 Pictures with bad visibility were excluded. To estimate use of carrion, a
 block of ca 15 kg of frozen reindeer slaughtering remains (originally
 produced as dog food and consisting of tendons, fat, small entrail and
 meat fragments) was placed at 2-3 m in front of each camera and replaced
 two to three times during the season. For each photo, we recorded whether
 the carcass was present.
description: # Effects of resource availability and interspecific interactions on
 Arctic and red foxes' winter use of ungulate carrion in the
 Fennoscandian low-Arctic tundra
 [https://doi.org/10.5061/dryad.41ns1rnnn](https://doi.org/10.5061/dryad.41ns1rnnn) This dataset is related to a two species occupancy study accessible on [https://doi.org/10.1002/ece3.11150](https://doi.org/10.1002/ece3.11150). ## Origin of the data A raw and regularly uptadet version of the camera trap dataset is accessible on COAT data portal [https://data.coat.no/dataset/v_scavengers_cameratraps_v1](https://data.coat.no/dataset/v_scavengers_cameratraps_v1). COAT is a project aiming to give robust documentation and predictions on climate change impacts on biodiversity, natural resources and ecosystem processes in the Norwegian Arctic, as a basis for management interventions and adaptations. ## Description of the data and file structure This repository contains two main datasets, located in two different folders: * **all_varanger_data**: this folders contains all the information related to individual pictures. Information is gathered in individual .rds files, with one file per year ("all_varanger_yyyy.rds"). Each file consists of a R dataframe, where lines correspond to pictures. Several information regarding the pictures are given: * *site* : one of the 6 study sites in the study area. * *loc*: code for individual cameras. * *datetime*: date and time of triggering. * *vis*: indicator (0/1) of the picture visibility. * *contrast/bright/saturation*: general information about the pictures. Contains NA most of the time. * *temp:* temperature recorded by the camera trap. Contains NA most of the time * *newbait*: indicator (0/1) of wether a new carrion block (frozen reindeer remains) was reintroduced between this picture and the previous one. * *baitvisible* (2005 - 2014) or *bait* (2015- 2021): indicator of wether the bait was visible on the picture. the name of this column was changed in 2015, but both columns are present on all datasets. Therefore *baitvisible* only contains NA values before 2015. * *bait_corr*: indicator (0/1) of wether the carrion block was present in front of the camera. This indicator was obtained from the *bait* or *baitvisible* column, with a correction to account for days where the bait was present but not visible. *baitID:* unique carrion identifie * *bait_days*: number of days since the introduction of a given carrion * *julian1/julian2*: number of days since january 1st. *julian1* considers days to start at 0:00AM and *julian2* at 0:00PM (to match with the nocturnal activity of some of the considered species). * *daynight*: indicator of wether the picture was taken during the day or the night * *light2:* same indicator as above but that also accounts for morning and evening twilights * *Human*/*ArcticFox*/*RedFox*/*Wolverine*/*Raven*/*Crow*/*Magpie*/*Havorn* (white-tailed eagle)/*Kongeorn* (golden eagle)/*Rein* (reindeer)/*Moose*/*HerringGull*/*WnowyOwl*: indicator of wether a given species was present on the picture. * **Metadata_and_covariates**: this folders contains all the metadata and covariates used in the multi-species occupancy analysis in 4 separate files: * *cam-coords-vegprod-hum.txt*: long/lat coordinates of the cameras and proportion of productive habitat in a 5 and 10km radius. * *camera_attributes_2019.txt*: long/lat coordinates of the cameras and altitude, distance to road, to forest and to the coast. All numbers are given in meters. * *storskala_04-21.txt*: abundance index for 5 rodent species from a snap-trapping campaign between 2004 and 2021 (see [https://doi.org/10.1073/pnas.1012714108](https://doi.org/10.1073/pnas.1012714108) for more information). * region: region of the trapping plot * plot: name of the plot * year: trapping year * season: trapping season (fall or spring) * llem/moec/mruf/mrut/rodsp: number of rodents trapped for each species (llem: Norwegian lemming, moec: tundra vole, mruf: grey-sided vole, mrut: Northern red-backed vole, rodsp: other rodents) * *foodStations_kernels_2018-2021.rds*: density of feeding stations in the study area for the 4 years after the feeding program was initiated. This density was estimated using kernel density estimators with the actual location of the feeding stations. Any additional information regarding how data was processed can be found on the article. ## R Codes All R codes required to run the analysis are available on [https://github.com/SimLacombe/TundraFoxes.](https://github.com/SimLacombe/TundraFoxes.)