Data from: Prudent burrow-site selection in a landscape of fear
Data files
Sep 25, 2023 version files 8.13 KB
Abstract
Prey animals should select safer breeding sites over riskier sites of otherwise similar habitats. This preference, however, may differ between conspecifics of different competitive abilities if the costs of intraspecific competition overpower the benefits of breeding in a safer site. Our goal was to test this hypothesis by exploring the burrow site selection of different-sized desert isopod (Hemilepistus reaumuri) females near and away from burrows of a scorpion predator. We found that larger females are more likely to occupy new burrows than smaller females, regardless of whether these burrows were close or away from scorpion burrows. We also found that larger females stayed longer in safer burrows and that smaller females tended to stay longer in riskier sites even in the absence of direct competition, implying a prudent burrow site selection. We found no association between male size and the tendency to occupy or to spend time in a burrow, regardless of whether these burrows were close or away from scorpion burrows. Our work highlights the need to consider intraspecific competition when exploring how predators regulate prey behavior and the consequences of these changes on prey mating patterns.
README: Data analysed for 'Prudent burrow-site selection in a landscape of fear'
Experimental setup and where the data was collected
In March 2021, we conducted a field experiment at the Avdat Research Station, Negev desert, Israel to explore the isopods nest-site selection. We established 14 experimental blocks, each including two groups of four cylindrical holes that were dug in the corners of a square. The minimal distance between the two burrow-groups was one meter. In each block, we dug a 10 cm long scorpion-burrow in the middle of one randomly chosen burrow-group. The neighboring burrow-group in each block served as a no-scorpion safe control. To all scorpion-burrows, we introduced scorpions of similar size.
How the data was collected
Each experiment lasted for two consecutive days. The experiment was started at the peak of the isopods daily dispersal activity. At the end of day one, the experiment was paused due to reduced isopod activity. On day two, the experiment was resumed and ended in a manner similar to day 1. At the end of day two, all isopods still inside burrows were collected, their body weight measured (in grams) and they were released. During the experiment, each block was monitored by one person. Any isopod visiting a hole was focally observed. Their activity near and inside the hole was recorded including whether the isopod occupied the hole or rejected it, and if occupied, for how long did the isopod stay inside (in seconds). Isopods that came in contact with a hole were temporarily collected after departing from the experimental blocks, and then were sexed, weighted, temporarily marked and released.
Details of the dataframes
'pram_summ_acc_rej' - Dataframe used to analyse the likelihood of isopods occupying a burrow. The columns are:
1. id - Individual unique identity of each isopod.
2. burrows_visited - Each burrow within an experimental block had an unique identity. Which burrow did the isopod visit?
3. sex - sex of the isopod
4. weight - Body weight of the isopod (grams)
5. pred_pres - Whether there is a predator present close to the burrow (R or S, for risky or safe)
6. burrow_block - Unique identity of the experimental block. There were 14 such blocks.
7. occupied_till_end - Did the isopod occupy that hole till the end of the trial? (1 for yes)
8. terrace - On which terrace was the trial conducted?
9. in_out_brief - Once the isopod interacted with the hole, did it enter or leave?
10. in_out_brief_num - Same as in_out_brief column, but numbered for ease of performing analyses in R (1 for enter and 0 for leave)
'pram_summ_duration' - Dataframe used to analyse the time isopods spent inside the burrows\, once it was occupied. The only new column in the dataframe compared to the previous one is:
1. duration_in_out - The time duration spent inside by the isopod (seconds)
All analyses were performed using R version 4.1.2, models were run using the packages glmmTMB or lme4. Post-hoc analyses to obtain estimated marginal means (EMMs) were performed using package "emmeans"
Methods
In March 2021, we conducted a field experiment at the Avdat Research Station, Negev desert, Israel to explore the isopods’ nest-site selection. We established 14 experimental blocks, each including two groups of four cylindrical holes that were dug in the corners of a square. The minimal distance between the two burrow-groups was one meter. In each block, we dug a 10 cm long scorpion-burrow in the middle of one randomly chosen burrow-group. The neighboring burrow-group in each block served as a no-scorpion “safe” control. To all scorpion-burrows, we introduced scorpions of similar size.
Each experiment lasted for two consecutive days. The experiment was started at the peak of the isopods’ daily dispersal activity. At the end of day one, the experiment was paused due to reduced isopod activity. On day two, the experiment was resumed and ended in a manner similar to day 1. At the end of day two, all isopods still inside burrows were collected, their body weight measured (in grams) and they were released. During the experiment, each block was monitored by one person. Any isopod visiting a hole was focally observed. Their activity near and inside the hole was recorded including whether the isopod occupied the hole or rejected it, and if occupied, for how long did the isopod stay inside (in seconds). Isopods that came in contact with a hole were temporarily collected after departing from the experimental blocks and then were sexed, weighed, temporarily marked, and released.
Usage notes
All analyses were performed using R version 4.1.2, models were run using the packages “glmmTMB” or “lme4”. Post-hoc analyses to obtain estimated marginal means (EMMs) were performed using package "emmeans".