Probability of Detecting Band-Tailed Pigeons During Call-Broadcast Versus Auditory Surveys

Abstract: Estimates of population trend for the interior subspecies of band-tailed pigeon (Patagioenas fasciata fasciata) are not available because no standardized survey method exists for monitoring the interior subspecies. We evaluated 2 potential band-tailed pigeon survey methods (auditory and call-broadcast surveys) from 2002 to 2004 in 5 mountain ranges in southern Arizona, USA, and in mixed-conifer forest throughout the state. Both auditory and call-broadcast surveys produced low numbers of cooing pigeons detected per survey route (x̄ ≤ 0.67) and had relatively high temporal variance in average number of cooing pigeons detected during replicate surveys (CV ≥ 161%). However, compared to auditory surveys, use of call-broadcast increased 1) the percentage of replicate surveys on which ≥1 cooing pigeon was detected by an average of 16%, and 2) the number of cooing pigeons detected per survey route by an average of 29%, with this difference being greatest during the first 45 minutes of the morning survey period. Moreover, probability of detecting a cooing pigeon was 27% greater during call-broadcast (0.80) versus auditory (0.63) surveys. We found that cooing pigeons were most common in mixed-conifer forest in southern Arizona and density of male pigeons in mixed-conifer forest throughout the state averaged 0.004 (SE = 0.001) pigeons/ha. Our results are the first to show that call-broadcast increases the probability of detecting band-tailed pigeons (or any species of Columbidae) during surveys. Call-broadcast surveys may provide a useful method for monitoring populations of the interior subspecies of band-tailed pigeon in areas where other survey methods are inappropriate.     

ACTION SPECTRA OF PHOTOMORPHOGENIC INDUCTION AND PHOTOINACTIVATION OF GERMINATION IN ARABIDOPSIS THALIANA

Detailed action spectra for photoinduction and photoinactivationof germination of the crucifer, Arabidopsis thaliana, have beendetermined. The photoresponse has a typical red, far-red sensitivitywith a peak susceptivity for induction at 660 mµ and twomaxima at 720 and 740 mµ for inactivation. The responsecurve for induction is a logarithmic function of dose and forinactivation a linear function of dose. The close similarity of the action spectra with other photomorphogenicaction spectra in diverse plant tissues indicates that thereis little attenuation by screening pigments or scattering beforethe photoreceptor is reached. The low dark germination percentageand the reproducible light sensitivity make the system advantageousfor the study of photoimetic substances. (Received October 1, 1960; )