Table 3.

Study set‐up characteristics that influence detection by CTs at different orders of detection

Characteristica	Direction and magnitude of effect on detection probability per orderb						Mechanism	Studies needed	When to correct forc	References
	1	2	3	4	5	6
CT density		+	+	+			Contact with CTs		Design	(Foster & Harmsen, 2011; Smith, Legge, James, & Tuft, 2017)
CT heightd					0/− −	(+/−)	PIR sensor functionality		Design	(Jacobs & Ausband, 2018; Meek, Ballard, & Falzon, 2016)
CT orientation (angle relative to the ground)e					(+/−)	(+/−)	PIR sensor functionality and identification of detected animals	Application of multiple CT setups	Design	None
CT orientation (horizontal or vertical)					+/−	+/−	PIR sensor functionality and identification of detected animals	Application of multiple CT setups	Design	(Smith and Coulson, 2012)
CT orientation (relative to the sun)f						(+/−)	Identification of detected animals	Application of multiple CT setups	Design, Season	None
Duration of deployment		++	++	++			Contact with CTs		Design	(Larrucea et al., 2007; Smith et al., 2017; Stokeld et al., 2016)
Number of CTs per trapping station		+	+	+	+	+	Contact with CTs, retention time in front of CT, and identification of detected animals		Design	(O'Connor et al., 2017; Smith et al., 2017; Stokeld et al., 2016)

^aCharacteristics are seen as continuous variables unless otherwise stated in the table or the footnotes, where the direction of the effect given is with an increase in the characteristic. For example, detection probability increases with an increase in CT density.

^bDirection and magnitude of effect on detection probability given in a scale from ++ to − − with 0 if no effect was found, biases given between brackets are not based on literature but estimates from the authors. When multiple studies reported contrasting results, we give the reported range separated with a /.

^cFactor given needs to be corrected for if multiple of these are considered in a study (see main text). Design refers to studies using multiple study designs.

^dThe distance between the animal and the CT increases with increasing CT height, potentially resulting in better (for close animals) or worse (for animals further away) identification of species and individuals.

^eChanging the angle of the CT might change PIR sensor functionality (due to the targeted Fresnel lens: Welbourne et al., 2016), and at the 6th order, it might influence the ability to identify species or individuals due to a changed perspective.

^fAlthough several studies mention that direct sunlight can reduce visibility and thus identification of species or individuals (e.g., Meek et al., 2014), we could not find any study testing for an effect of CT orientation relative to the sun on detection probability.