Do Band-Tailed Pigeons Seek a Calcium Supplement at Mineral Sites?

We tested the hypotheses that mineral sites in western Oregon are used by Band-tailed Pigeons (Columba fasciata) to supplement dietary calcium and sodium. We compared mineral composition of sites used by Band-tailed Pigeons, adjacent unused sites, and three major food items during the nesting season. Sixty-five percent of used mineral sites were low in calcium (<200 ppm), whereas mean concentrations in food items were high (1,960–2,290 ppm). All but one used mineral site were high in sodium (≥678 ppm), whereas mean concentrations in food items were low (20–254 ppm). Food items were high in mean concentrations of potassium (12,470–26,980 ppm) and potassium:sodium ratios (138–656). Used and adjacent, unused, estuary mineral sites were similar in calcium and sodium concentrations. We hypothesize that because of insufficient sodium intake and inefficient sodium retention, Band-tailed Pigeons seek a sodium source to supplement their diet during the nesting season. Use of mineral sites probably depends upon sodium concentration, but also vegetation structure, development, human activity, and congregation use by Band-tailed Pigeons. Used mineral sites appear to be scarce in western Oregon, and are seemingly essential resources for this species. Eighty-six percent of known currently-used mineral sites are privately owned and subject to possible alteration from land-use practices. Mineral sites used by Band-tailed Pigeons should be included in the overall management scheme for maintaining stable breeding populations of this species.

Serum and Pituitary Prolactin Changes in the Band-tailed Pigeon (Columba fasciata) in Relation to the Reproductive Cycle

Relative changes in serum and pituitary prolactin in the band-tailed pigeon were measured by radioimmunoassay. It was found that serum prolactin concentrations rose substantially prior to crop gland development and reached a maximum during the period of ovulation. At the same time, there was a corresponding depletion of pituitary prolactin. The reciprocal nature of these changes continued for the remainder of the reproductive cycle. Although the lack of antigonadal response to increased levels of prolactin is clearly demonstrated by the male of this species, this problem remains unresolved in the female.

Studies on the band-tailed pigeon (Columba fasciata) in British Columbia. 1. Seasonal changes in gonadal development and crop gland activity

Band-tailed pigeons ovulate in British Columbia from May through July although apparently not all females do so early in the breeding season. Males are in breeding condition when they arrive after the northward migration in April and remain so until late July. Evidence suggests that two clutches (one egg each) may be produced during the breeding season. The female's ability to ovulate white crop feeding the squab provides additional evidence of two clutches. Four stages of crop gland development are described in detail and the usefulness of this gland to indicate breeding status is demonstrated. Many birds had active crops when shot during the hunting season indicating a potentially reduced recruitment of the squabs being fed at this time.