Band-Tailed Pigeon Use of Supplemental Mineral

Band-tailed pigeons (Patagioenas fasciata) congregate at and use mineral sites (mineralized water or soil) throughout their range; however, information needed to interpret counts of pigeons at these sites and make inference to population abundance and distribution is lacking despite current monitoring efforts. Our objectives were to determine if we could create a mineral site used by band-tailed pigeons; test whether pigeons seek supplemental sodium, calcium, or both; describe the pattern of pigeon use of mineral sites seasonally and within days by individual birds; and evaluate implications of precipitation, fog, temperature, and mineral concentration on pigeon visitation patterns. We attracted hundreds of pigeons/day to a created mineral site that offered sodium, calcium, or both in a forested area in southwestern Washington, USA where we captured and applied passive integrated transponder (PIT) tags to 771 pigeons and monitored mineral use during 2010–2014. When offered paired sodium and calcium stations, pigeons near exclusively consumed sodium, and pigeons continued to use the created mineral site for 3 years when calcium was not available. Pigeons visited sodium stations on average once every 12 days during June through early October; reducing available sodium concentration from 3,500 ppm to 1,000 ppm had no significant effect on visitation rates. Counts of pigeons at mineral sites varied with precipitation, sex, and time of season; consequently, comparison of pigeon counts among mineral sites can be biased if not accounting for these factors. Our results show that pigeons can be attracted to mineral stations, and that counts at mineral sites and stations allow opportunities for population monitoring