Habitat availability, dietary mineral supplement, and measuring abundance of band -tailed pigeons in western Oregon

My objectives were to: (1) develop a point count technique for estimating relative abundance of band-tailed pigeons (Columba fasciata monilis ), (2) determine the availability, distribution, and interspersion of mineral sites, and nesting and foraging cover in relation to abundance of band-tailed pigeons in west-central Oregon, and (3) test the hypothesis that mineral sites are used during the breeding season to supplement dietary calcium, as previous researchers suggested.;Point counts of cooing band-tailed pigeons offer an effective means of estimating the abundance of band-tailed pigeons in space and time, and have the potential for use as a range-wide population survey technique. Point counts should: be ≥800 m apart, begin 10 minutes before official local sunrise, last 1-hour in duration, and in the Oregon Coast Range, be conducted between 16 June and 24 July. Point counts may also be conducted between 25 July and 16 August, but a multiplicative factor of 0.49 must be added to counts to make them comparable to earlier counts.;My data indicate that band-tailed pigeon populations within the central Coast Range of Oregon are not limited by availability of potential nesting and foraging cover and mineral sites at landscape scales less than their home range size (about 11,000 ha). Band-tailed pigeons were almost uniformly distributed, except that they were more abundant along the western 1-third of the central Coast Range than along the eastern 1-third. This pattern was correlated with forage distribution. Possibly the availability of red elder (Sambucus racemosa var. arborescens) and cascara ( Rhamnus purshiana) imposes a constraint on the Pacific Coast band-tailed pigeon population size within the range of these species.;The data I collected do not support the hypothesis that band-tailed pigeons use mineral sites to supplement dietary calcium. Instead, band-tailed pigeons are associated with mineral sites with high sodium concentration. Use of mineral sites coincides with the consumption of red elder and cascara berries during the breeding season; these berries are especially low in sodium, but high in energy, protein, and potassium. I hypothesize that band-tailed pigeons visit mineral sites to supplement dietary sodium when foraging exclusively on red elder and cascara berries.