Tejon Ranch Exclosure Experiment - Tick (family Ixodidae: subclass Acari) and Small Vertebrate Responses
Data files
Jan 27, 2025 version files 289.77 KB
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lizardcounts_02172021.csv
82.27 KB
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mammal_counts_02182021.csv
8.23 KB
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README.md
3.42 KB
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tejon_mamliz_popestimates.csv
673 B
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Tejon_MeanComparisons_Dataset.csv
60.57 KB
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Tejon_MixedModels_Dataset.csv
75.48 KB
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Tick_19.csv
15.95 KB
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Total_Ticks_2016_to_2018.csv
43.17 KB
Abstract
Large-bodied wild ungulates are declining worldwide, while domestic livestock continue to increase in abundance. Such changes in large herbivore communities should have strong effects on the control of ticks and tickborne disease as they can indirectly modify habitat and directly serve as final hosts for ticks’ lifecycles. Numerous studies have now linked changing ungulate communities to changes in tick populations and disease risk. However, the effects of changing large herbivore communities are variable across studies, and the effect of climate as a mediating factor of this variation remains poorly understood. Also, studies to date have largely focused on wildlife loss without considering the extent to which livestock additions may alter tick populations, even though livestock replacement of wildlife is the global norm. In this study, we used a large-scale exclosure experiment replicated along a topo-climatic gradient to examine the effects on tick populations of both large herbivore removal and livestock additions. We found that while questing ticks increased modestly, by 21%, when large herbivores were removed from a system they decreased more substantially, by 50%, when livestock (in the form of cattle) were added. Importantly, in addition to the direct effects of climate on tick populations, climate also mediates the effect of ungulates on questing tick density. Particularly the addition of livestock under the most arid conditions decreased tick presence, likely due to changes in ground-level microclimates away from those beneficial to ticks. Overall, the work contributes to our understanding of tick population responses to globally common human-induced rangeland alterations under the concurrent effects of climate change.
README
Data Files
Tejon_MeanComparisons_Dataset.csv: contains tick drag data aggregated by year, month, site, block, and plot. The tick drag data includes a total column of all tick species collected and additionally, four columns representing the three tick species collected via drags deoc (Dermacentor occidentalis), ipac (Ixodes pacificus), deva (Dermacentor variabilis), and other (for non-identified ticks). Finally, it contains a unique numerical ID for each of the 27 exclosure treatments of TREE, plotID.
This data was used in the manuscript's analyses, which investigated the individual and interactive impacts of climate level and herbivore treatment on tick abundance.
Tejon_MixedModels_Dataset.csv: in addition to tick drag data, it contains columns liz_estimate and mam_estimates created by the results located in the tejon_mamliz_popestimates.csv file detailed below. This data set analyzes climate and herbivore treatment impact on lizard and small mammal populations. These results and figures are included in the Appendix. NAs in the liz_estimate and mam_estimates columns indicate when model estimates were omitted because the resulting estimations were unrealistic.
Total_Ticks_2016_to_2018.csv: raw data from field tick drags from 2016 - 2018.
Tick_19.csv: raw data from field tick drags occurring in 2019.
lizardcounts_02172021.csv: raw data file containing lizard surveys completed in the field. Lizard surveys were completed by mark and recapture surveys that took place at only the Arid and Intermediate climate level plots (N=18). The plots were sampled for three consecutive days, and when a lizard was spotted, they were sprayed with a scale-safe paint. Each day, there was a different color of paint. For example, in a row in the data set, a lizard spotted on day 1 will have a 1 in the column day1. If it were not spotted on day 2, there would be a zero in the day2 column. And if it were spotted on day 3, there would be a 1 in the day3 column.
mammal_counts_02182021.csv: raw data file containing small mammal trapping data completed in the field. Small mammal surveys were completed using mark and recapture surveys. Each plot was surveyed for three consecutive days. When an animal was caught, they were given a metal ear tag (IACUC # 904.1). The column tag in the data file indicates the tag number assigned to the animal. Each row indicates how many times day1, day2, and day3 that animal was caught over our sampling period. Those with an NA in the tag column were, for some reason (e.g., juvenile or deformity), unable to be tagged.
tejon_mamliz_popestimates.csv: data file containing the abundance estimate results for small mammal and lizard populations using Rcapture to evaluate the raw data (two data files directly mentioned above) recorded in the field.
Dataset Clarifications
site = Climate Level, a factorial column denoting three climate levels of the study - Arid, Intermediate, and Mesic.
plot = Herbivore treatment, a factorial column denoting three herbivory treatment types used in the study. Within the data set, they are referred to as Open, Partial, and Total. For data figures and discussion of results and analyses within the manuscript, these are changed to:
- Open = Cattle and Wildlife (CW)
- Partial = Wildlife (W)
- Total = Minus Cattle and Wildlife (-CW)