Band‐tailed pigeon use of supplemental mineral

Abstract

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. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Non‐random distribution of ungulate salt licks relative to distance from North American oceanic margins

“…Geophagy at both natural and artificial sodium sites has also been observed in some North American granivorous birds (e.g. Rea, 2017;Sanders & Koch, 2018), which, as herbivorous taxa, are similarly salt-deprived. Thus, large-scale biogeographical variation in the extent of marine salt deposition may affect salt-seeking behaviour in a wide variety of wildlife.…”

Minerals in gastroliths and foods consumed by band‐tailed pigeons

“…However, although we were only able to obtain 1 useful crop milk sample form the Interior region, there was no indication that the mineral content of this sample was different than that for Pacific Coast pigeons despite population differences between regions in access to supplemental mineral sites and similarities in food items consumed. Sanders and Jarvis (2000) and Sanders and Koch (2018) discussed how use of mineral sites by Pacific…”

“…Although calcium concentration in grit was greater for Pacific Coast pigeons than Interior pigeons, this pattern is in contrast to the explanation of why Pacific Coast pigeons use supplemental mineral sites (Sanders and Koch 2018, dietary food or grit mineral deficiency) and Interior pigeons do not. Also, there is no evidence that Pacific Coast pigeons seek supplemental calcium at mineral sites Jarvis 2000, Sanders andKoch 2018). Calcium is generally available in parent materials (limestone, marble, gypsum) of the Interior region and not in the Pacific Coast region.…”

“…Data indicate the ion sought at mineral sites is sodium (Sanders and Jarvis 2000, Sanders and Koch 2018) but was previously thought to be calcium (March and Sadleir 1972, 1975; Jarvis and Passmore 1992; Braun 1994). Sanders and Koch (2018) determined that pigeons visited a supplemental sodium site on average once every 12 days during June through early October in Washington, USA. Pigeon use of supplemental sodium during the breeding season has been associated with egg and crop milk (curdlike substance formed in the crop and fed to hatchlings) production and may be exacerbated by a berry diet low in sodium and high in moisture and potassium content (Sanders and Jarvis 2000, Sanders and Koch 2018), but use of supplemental sodium can occur year around (Sanders and Koch 2018).…”

First record of geophagy by a Ramphastidae species (Piciformes)

“…The supplementation of nutrients and the support for mechanical digestion (Downs et al 2019) are among other motivations we suppose could encourage a toucan to consume soil. Several hypotheses indicate the most desired mineral by birds in clay soils is sodium (Powell et al 2009;Lee et al 2010;Sanders and Koch 2017), which cannot be sufficiently acquired through diet when part of the bird's usual food items are scarce (Sanders and Koch 2017). Red-breasted Toucans feed mostly on fruits, but their diet is richer in protein items as eggs, small vertebrates, and invertebrates (Leite et al 2010;Jesus et al 2012;Ribeiro-Silva et al 2018), which can provide enough sodium for its nutritional health.…”