The influence of predators on prey species was expressed as the sum of the field metabolic rate (sFMR) of all potential avian and mammalian predators of hares present in a hunting lease during the year before the collection of the harvested hares. We assigned each predator to a specific predator type (i.e., all birds, Pelecaniformes, mammal omnivores, and mammal carnivores) based on Nagy et al. ( 1999 ) (Appendix S6). We then calculated the average of the lower and higher limit of the body weight for each predator species (BWavg; birds: Del Hoyo et al., 1992 ; Del Hoyo et al., 1994 ; Del Hoyo et al., 1996 ; Del Hoyo et al., 1999 ; Del Hoyo et al., 2009 ; mammals: Lange et al., 2003 ). ( 1999 ) to calculate field metabolic rate (FMRBWavg) for each predator species (per Equation 1). Finally, for birds, we calculated the proportion of the year each species was resident in the Netherlands, as many birds migrate toward southern latitudes in winter (Vogelbescherming, 2017 ).
dos.3.1 Model investigated
First, i investigated new correlation involving the sum of the predator occupation kcalorie burning (sFMR) while the threat of search death given that predictor variables therefore the body condition directory once the effect changeable having fun with a great linear blended model (LMM) during the R (package lme4 type step 1.1-12; Bates ainsi que al., 2015 ; n = 66). Additionally, i examined an option LMM towards total number out of predators due to the fact predictor variable and body status list since response variable to research whether predator variety top shows you body condition than the sFMR (get a hold of Appendix S4 to own an introduction to the global habits suitable). I included the latest intercourse of hares, what their age is classification, therefore the months due to the fact start of the studies collection due to the fact repaired consequences, due to the fact people hares fatten right up within many weeks in the bottom of the year to set up for the next breeding 12 months (Valencak et al., 2009 ). In addition to, looks updates varies during the seasons (Van Vuuren & Coblentz, 1985 ) and scales in different ways ranging from men and women (Murray, 2002 ). We incorporated google search book since the random foundation, having subareas nested contained in this google search lease. I omitted one to mature women that had a highly low body pounds (2416 grams) in contrast to other adult people ( ± SD = 3642 ± 318 grams).
Chance of browse mortality are indicated as percentage of hares test in the total number out-of hares mentioned in a hunting rent inside the query drives
2nd, i investigated the brand new correlations anywhere between sFMR additionally the threat https://www.datingranking.net/it/incontri-cougar of bing search mortality as predictor details as well as the average pounds of adrenal gland as effect variable having fun with a good LMM (n = 66). We incorporated the age class and you can sex off hares because repaired consequences, since adrenal glands from animals try assumed to improve sizes by persistent connection with fret during their lifetime (Much harder & Kirkpatrick, 1994 ). Concurrently, we expected an intercourse-particular worry impulse and you will perception regarding risk, because the female have to fatten around plan their very first litter in winter months (Valencak mais aussi al., 2009 ) and therefore probably function in different ways so you can predation risk weighed against boys. Once more, i utilized subareas nested contained in this hunting book due to the fact haphazard foundation. We omitted one mature ladies that had a very high mediocre lbs of your own adrenals (0.61 g) compared to the remainder mature people ( ± SD = 0.29 ± 0.076 grams). Similarly to human body condition, i also-ran a model into final number away from predators given that predictor variable.