Selasphorus platycercus
broad-tailed hummingbird

Selasphorus platycercus is a migratory species with some resident populations in Mexico. Migratory populations breed in Colorado and Wyoming, while tropical resident populations breed in central Mexico. Their winter range expands from northern Guatemala to northern Mexico. Information on non-migratory populations is lacking (Calder and Calder, 1992).

The breeding habitat of broad-tailed hummingbirds includes willows around wet or dry stream beds, pinion, juniper, spruce and oak woodlands. They are known to nest as high as 3,230 m. In their winter range, which overlaps with the breeding range of resident populations in Mexico, broad-tailed hummingbirds use thorn and oak forests at lower elevations, and mixed oak-pine and cypress as well as fir forests at higher elevations. Because of the year-round availability of hummingbird feeders in some areas, some individuals have taken up residence in urban and suburban areas of southwestern United States (Calder and Calder, 1992).

Broad-tailed hummingbirds are sexually dimorphic. Males have a metallic iridescent-rose colored gorget, green colored sides and back with some rufous color in the tail. The females are less colorful, lacking a complete gorget, and exhibiting buffy colored sides and a green back. Females are larger than males but body mass can vary during the course of a day based on nectar intake. Juvenile males look like adult females and are difficult to distinguish. (Kaufman, 2000).

Life expectancy is 1.6 years based on the 50% mark on a survivorship curve in males and 1.9 years in females. The highest recorded age for wild females is 12 years and 8 years in males. (Calder and Calder, 1992)

Males in the breeding season are active for an average of 910 minutes/day out of an 878 minute solar day, and active for 608 minutes/day during a 602 minute solar day in an Arizona winter range. In the Mexico winter, they average 592 active minutes/day for a 657 minute solar day. Females spend 78% of their day on the nest during incubation and 62% of day on the nest during brooding.

Males are territorial and will vigorously defend their territory from intruders during mating season. Individuals will challenge vocally and chase other individuals off of their territory. Territory size will depend on food availability as well as density of birds.

Individuals from migratory populations migrate north in the spring abandoning the non migrant populations in central Mexico. They reach southern Arizona from late February to early March. By late April-early May individuals reach northern Arizona and Colorado. They reach the upper limit of their distribution (Idaho) by mid May. After breeding, they start their south-bound migration into their winter range in Mexico, arriving there by August. Males arrive before females and juveniles, occupying the best quality territories (Calder and Calder, 1992).

Broad-tailed hummingbirds feed on floral nectar and small insects. They usually visit flowers with red tubular corollas like the Scarlet Gilia (Ipomopsis aggregata). In the wintering grounds Broad-tailed Hummingbirds are not the dominant species and may have to forage on less preferred flowers. A study done with Ruby Throated, Rufous and Broad-tailed Hummingbirds suggested that there may be an element of observational learning involved in learning to forage on novel food resources. Insects are caught in air as well as by gleaning from foliage. There is a daily steady gain in body mass of individuals from foraging over the course of a day, with a total gain of 30 to 34% of their body mass just before flying to their roosting sites. This large foraging bout before roosting is probably needed to store energy for overnight thermoregulation.

Nectar used by hummingbirds contains large amounts of water that a hummingbird has to pass through its body either by absorbing it into the intestinal tract to be processed by the kidneys or just letting it pass through the tract without absorption. Water intoxication would be a major problem for most vertebrate species under these conditions but hummingbirds are able to excrete large amounts of dilute urine and handle large amounts of water being processed by the kidneys. They do however vary the amount of nectar taken in based on the sugar concentration of that nectar.

Nectar is taken from the following plants: Ipomopsis aggregata, Aquilegia elegantula, A. triternata, Penstemon spp., Castilleja spp., Salvia spp., Echinocereus grandiflorum, Mertensia oblongiforum, Delphinuim nelsoni, Ribes ciliatum, Cestrum terminale, Buddleia dara and Senecio angulifolius.

(Calder and Calder, 1992; Calder, 1994; McWhorter and Martinez del Rio, 1999; Altshuler and Nunn, 2001)

Broad-tailed hummingbirds are important pollinators of the plant species they forage on. (Calder and Calder, 1992).

Hummingbirds, especially in areas where feeders are present, can be popular attractions for tourists to want to visit. Broad-tailed hummingbirds can be incorporated into ecotourism in areas where they are prevalent.

Increased use of feeders help to sustain populations in times of resource scarcity (Calder and Calder, 1992).