Distribution, abundance, detection probability, and nest-site selection of Band-tailed Pigeons in southern Arizona
The band-tailed pigeon (Patagioenas fasciata) is a migratory game bird that breeds in two distinct regions within North America - a coastal population in California, Oregon, Washington and British Columbia and an interior population in Mexico, Colorado, Utah, New Mexico and Arizona. Harvest data from the southwestern U.S. indicate that populations of the interior sub-species of band-tailed pigeon (P. f. fasciata) have declined since the late 1960’s. Management of these populations requires better knowledge of the distribution, abundance, and population trajectory of the species. However, no standardized protocol currently exists for monitoring band-tailed pigeons in the interior region.
From 2002 to 2004, we evaluated 5 potential survey methods (short-duration auditory surveys, longer-duration auditory surveys, call-broadcast surveys, capture-recapture, and bait-site counts) in an attempt to identify a precise, accurate, and cost-effective survey method for monitoring interior populations of band-tailed pigeons. Because information on band-tailed pigeon natural history is lacking, we also collected data on breeding biology, reproductive success, nest site characteristics, rate of Trichomoniasis infection, movement patterns, and potential causes of mortality for band-tailed pigeons by trapping pigeons and tracking radio-marked pigeons. In addition, we collected data on the effects of recent wildfires on band-tailed pigeons and estimated the population trajectory of band-tailed pigeons in the Santa Catalina Mountains by repeating a survey originally conducted in the late 1960s. Our primary study site was located in the Santa Catalina Mountains, Arizona, but we also conducted fieldwork in 4 additional mountain ranges in southeastern Arizona and in mixed-conifer forests throughout the state.
Use of call-broadcast increased the average number of pigeons detected during surveys by 22% and increased the number of replicate surveys with ≥1 pigeon detection by 16% compared to strictly auditory survey methods. Moreover, based on estimates of detection probability, use of call-broadcast increased the accuracy of band-tailed pigeon counts during surveys. Relative to other survey techniques, we found that capture-recapture and bait-site counts were the least effective survey methods and will likely be of limited use for monitoring band-tailed pigeons in southeastern Arizona (and perhaps elsewhere in the interior region). Compared to other forest types, we detected cooing band-tailed pigeons more frequently at survey points located in mixed-conifer forest in southeastern Arizona. Density of cooing band-tailed pigeons in mixed-conifer forest throughout the state was low (mean = 0.0044 [SE = 0.0012] pigeons/ha). Numbers of band-tailed pigeons appear to have declined substantially (82%) in the Santa Catalina Mountains since the late 1960s.
We collected trichomoniasis samples from 23 captured pigeons in the Santa Catalina Mountains in 2003 and only 1 pigeon tested positive for the protozoan parasite. By tracking radio-marked pigeons, we observed movements of band-tailed pigeons up to 105 km between 4 mountain ranges (Santa Catalina, Rincon, Galiuro, and Huachuca Mountains) during the breeding season and located 12 band-tailed pigeon nests that were initiated between May and August. The odds of a band-tailed pigeon nesting in an area increased with increasing slope, more trees >100 cm DBH stand size class, and greater silverleaf oak (Quercus hypoleucoides) cover between 2 and 5 meters above ground. Nests were more successful in areas that were burned and that contained more snags in the vicinity of the nest. Overall nesting success was only 31.9%. Further research is needed to examine the impact of potential limiting factors on interior populations of band-tailed pigeons including mortality risks for adults and factors contributing to the low nest success rate observed during this study.
This project was funded by the U.S. Fish and Wildlife Service Webless Migratory Game Bird Research Program, the Arizona Game and Fish Department Heritage Fund (#I03004), and the U.S. Geological Survey. We thank the numerous technicians and volunteers who have made this project possible through their dedicated field work.
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- Hughes, K., C. Kirkpatrick, C. J. Conway, and J. deVos. 2006. "Nest-site selection and nesting success of band-tailed pigeons". 39th Joint Annual Meeting AZ/NM Chapters of The Wildlife Society and AZ/NM Chapters of the American Fisheries Society, Flagstaff, Arizona. Paper presentation.
- Kirkpatrick, C., C. J. Conway, K. M. Hughes, and J. deVos. 2005. "Call-broadcast increase probability of detecting band-tailed pigeons during surveys". American Ornithologists’ Union annual meeting, Santa Barbara, California. Paper presentation.