Comparative evaluation of thermal infrared imaging and spotlighting to survey wildlife. Focardi, S., De Marinis, A., Rizzotto, M., & Pucci, A. Wildlife Society Bulletin, 29(1):133–139, Ist. Naz. per la Fauna Selvatica, Via Ca' Fornacetta 9, 1-40064 Ozzano Emilia, Bologna, Italy, 2001.
abstract   bibtex   
Spotlighting (SL) is used widely to estimate animal abundance, but it yields density estimates that are underestimated and biased. Introduction of distance sampling has, to a large extent, contributed to solving these problems, but the reliability of this statistical method depends strongly on sample size. Thermal infrared (TI) imaging may improve number of observations, but very few studies have quantified performance of TI imaging relative to SL. This comparison is relevant because the high cost of a TI device is justified only by a significant increase of observations and a consequent reduction of labor costs. Our objectives were to compare animal detectability by SL and TI imaging as a function of animal size, species (red deer [Cervus elaphus], fallow deer [Dama dama], wild boar [Sus scrofa], red fox [Vulpes vulpes], European rabbit [Oryctolagus cuniculus], and brown hare [Lepus europaeus]), distance, and season. We also analyzed group size and composition for red deer and effect of grass height on detection of hares and rabbits. On average, TI imaging was more efficient (P<0.001) than SL, which detected only 53.8% of the animals observed by TI imaging. This was especially true for wild boar (92.1%), but both devices observed comparable red fox (P=0.60) and fallow deer (P=0.72) numbers. Relative detectability of the 2 devices was influenced by different factors: for red deer, TI was more efficient than SL in summer and autumn, but not in winter; male groups of red deer were better observed by TI imaging than by SL; and wild boars were better imaged at short (0-100-m) distances with TI. Relative effectiveness of both instruments was not influenced by grass height (P=0.92). Our results showed that wild boar should only be surveyed using TI imager and that a strong improvement of sample size can be obtained using TI for red deer, brown hare, and European rabbit.
@Article{Focardi2001,
  author      = {Focardi, S. and De Marinis, A.M. and Rizzotto, M. and Pucci, A.},
  title       = {Comparative evaluation of thermal infrared imaging and spotlighting to survey wildlife},
  journal     = {Wildlife Society Bulletin},
  year        = {2001},
  volume      = {29},
  number      = {1},
  pages       = {133--139},
  abstract    = {Spotlighting (SL) is used widely to estimate animal abundance, but
	it yields density estimates that are underestimated and biased. Introduction
	of distance sampling has, to a large extent, contributed to solving
	these problems, but the reliability of this statistical method depends
	strongly on sample size. Thermal infrared (TI) imaging may improve
	number of observations, but very few studies have quantified performance
	of TI imaging relative to SL. This comparison is relevant because
	the high cost of a TI device is justified only by a significant increase
	of observations and a consequent reduction of labor costs. Our objectives
	were to compare animal detectability by SL and TI imaging as a function
	of animal size, species (red deer \textit{[Cervus elaphus]}, fallow
	deer \textit{[Dama dama]}, wild boar \textit{[Sus scrofa]}, red fox
	\textit{[Vulpes vulpes]}, European rabbit \textit{[Oryctolagus cuniculus]},
	and brown hare \textit{[Lepus europaeus]}), distance, and season.
	We also analyzed group size and composition for red deer and effect
	of grass height on detection of hares and rabbits. On average, TI
	imaging was more efficient (P<0.001) than SL, which detected only
	53.8% of the animals observed by TI imaging. This was especially
	true for wild boar (92.1%), but both devices observed comparable
	red fox (P=0.60) and fallow deer (P=0.72) numbers. Relative detectability
	of the 2 devices was influenced by different factors: for red deer,
	TI was more efficient than SL in summer and autumn, but not in winter;
	male groups of red deer were better observed by TI imaging than by
	SL; and wild boars were better imaged at short (0-100-m) distances
	with TI. Relative effectiveness of both instruments was not influenced
	by grass height (P=0.92). Our results showed that wild boar should
	only be surveyed using TI imager and that a strong improvement of
	sample size can be obtained using TI for red deer, brown hare, and
	European rabbit.},
  address     = {Ist. Naz. per la Fauna Selvatica, Via Ca' Fornacetta 9, 1-40064 Ozzano Emilia, Bologna, Italy},
  file        = {:Focardietal2001.pdf:PDF},
  groups      = {Rodrigo},
  keywords    = {Brown hare, Census, Cervus elaphus, Dama dama, European rabbit, Fallow deer, Infrared, Lepus europaeus, Oryctolagus cuniculus, Red deer, Red fox, Spotlighting, Sus scrofa, Vulpes vulpes, Wild boar},
  owner       = {eric},
  subdatabase = {distance},
  timestamp   = {2006.11.05},
}

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