Gallo della salvia
Uccello Galliforme della famiglia Fasianidi, sottofamiglia Tetraonini, tribù Centrocercini, proprio della porzione occidentale degli Stati Uniti ricoperta da artemisia (sagebrush = salvia+sterpaglia), che si nutre principalmente di vegetali. L'esibizione del maschio nei riguardi della femmina consiste in andature impettite e nello sventolare la coda. Inoltre gonfia il sacco aereo esofageo che viene dapprima fortemente dilatato e quindi svuotato all'improvviso, producendo un suono simile a una sferzata che in condizioni favorevoli è percepibile anche a 300 metri di distanza. Un altro aspetto dell'esibizione è quando sbatte le ali per produrre un suono che è simile a quello di una spazzola strisciata sui piatti di una batteria e contemporaneamente rilascia aria dal sacco esofageo per produrre un rumore simile a un tonfo che ricorda quello di una grande pietra che cade in acqua profonda.
El Centrocercus urophasianus, urogallo de las artemisas o Gallo de salvia, es un habitante de los extensos matorrales formados por la artemisa, que le ofrecen abrigo y con cuyas hojas se alimenta. Vive en las llanuras en invierno y las estribaciones de las montañas en verano. En primavera, grupos de machos se exhiben ante las hembras formando un abanico erizado con la cola, hinchando el cuello y llenando los sacos aéreos de su pecho, y emiten unos sonidos profundos y burbujeantes. Las hembras escogen su pareja y anidan solas. los urogallos de artemisas están desapareciendo del oeste de EE. UU.: aunque su población se estimaba en millones, a finales del siglo XX quedaban unas 150.000 de estas aves, por lo que se ha abierto un centro para su protección en Dubois, Idaho.
Sage grouse are found year round as far north as SE Alberta and SW Saskatchewan. Their western limit is northern California and their eastern limit is North and South Dakota. Sage grouse are found as far south as Nevada. Sage grouse, as their name suggests, are always associated with some species of sagebrush (Artemisia spp.). These birds rely on sagebrush for leks, nesting sites, feeding sites, rearing sites, protection and wintering grounds. Sage grouse can be found in or near sagebrush habitats year round.
Secondary to sagebrush habitat, Sage grouse also require moist wetland and wet meadows (mesic sites) to aid in brood rearing. Thus, these areas are mostly occupied in late spring and summer. Another habitat requirement for the Sage grouse are areas suitable for lek sites. Lek sites need to be flat areas that are relatively visible to females. They can range in size from about 0.5 ha to 4 ha and can be located on knolls and ridges. These sites are found to contain little vegetation but are always surrounded by sagebrush communties.
Sage grouse are the largest of North American grouse and are sexually dimorphic. Males have a grey crown, markings on the back of the neck and yellow lores. The upper chest is brown and buff and the middle is composed of a large white ruff concealing oesophageal sacs that inflate during courtship. There is also a large black patch on the abdomen. The tail feathers of males are long and tapered with barring. Females have more cryptic plumage enabling them to blend into the environment during nesting. They show less white coloring than the males and are mottled with gray and brown to a higher degree. They also lack the oesophageal sacs that the males have. The throat of a female is predominantly gray and white. The tail of the female Sage grouse is not nearly as long as the male's.
The Sage grouse is a species that employs leks to select mates prior to reproduction (this aspect will be discussed in the next section). After the female has mated with a male on the lek, she will leave and construct a nest 2-6 metres from the lek. Once the nest in constructed, the hen will lay 1 egg about every 1.3 days for 9 days. This usually results in the female laying 7 or 8 eggs. Laying and incubation of the eggs usually takes about 37 days. After hatching, the females will remain with the hatched young. In about a week, a hatchling is able to fly short distances. At this time brood will move to a more mesic (wet) site where food will be more abundant. The young remain with their mother until the fall, at which time they segregate sexually into winter flocks. The following spring, the yearlings will find a lek site and begin the process of displaying and attracting a mate.
During the winter and spring, the Sage grouse is a social species. In the winter, flocks of sexually segregated (i.e. males and females are separated into different flocks) individuals are found. In the spring, during the breeding season, the flocks recombine at lek sites where breeding occurs. Sage grouse are generally sedentary, but over the winter months they have been known to move around seeking good sites for foraging. Perhaps the most interesting aspect of the Sage grouse's behaviour is its breeding system. As mentioned previously, Sage grouse are a lekking species. This means that every breeding season, sexually mature individuals gather at various sites. These sites are where males display to the females. The purpose of the display is to attract females and defend territories. The males whose display is most attractive to the female, will get to mate with her.
In early spring, males begin to return to the lek sites and establish territories. After a territory is established the male will begin displaying for the females. It has been found that the older and more experienced cocks attain 75-80% of the territories in a given lek site. If yearlings are able to establish territories they tend to be found on the outer areas of the lek while the older cocks are found nearer the middle. The males will remain on the leks from March to May, being most active at dawn and dusk. Females will attend the lek for usually 2 to 3 days, during which time the female will select a male and mate only once. After the female has mated, she will leave the lek to build a nest and lay her eggs.
The display of male Sage grouse consists of struts and tail-fanning. Also, he will inflate his oesophageal sac and display the olive-green gular sacs concealed under his feathers. Another component of the display is when the male flaps his drawn wings to make a "brushing" sound and releases air from his oesophageal sac to make a "plopping noise" (sounding like a large rock dropped into deep water).
Sage grouse lack a strong gizzard (an organ birds use to grind up food), as a result their diet is mainly soft foods. When a Sage grouse is very young (i.e. less than one week old), 60% of its diet is insects. But, as the bird ages, its diet progresses from being mainly insectivorous to herbivorous. By 12 weeks of age, 5% of a young Sage grouse's diet is insects. An adult Sage grouse therefore, will be predominantly herbivorous, selecting soft plants to consume. Sagebrush leaves (Artemisia spp.) constitute 60-80% of their diet in the summer and nearly 100% of their diet in the winter. Other plants consumed by Sage grouse include June Grass (Koeleria macrantha), Blue Gramma Grass (Bouteloua gracilis), and Western Wheatgrass (Agropyron smithii).
Hunting of the grouse for food and recreation has been historically important to humans. This species of bird positively benefits humans in that it provides aesthetic enjoyment for birdwatchers through observing and photographing their behavior on the lek sites. The Sage grouse can also act a an indicator of a healthy prairie ecosystem. If the sagebrush communities in North America are in danger, the decline of the Sage grouse can inidicate this. The Canadian populations of Sage grouse (Centrocerus urophasianus urophasianus) have been listed as endangered by the Committee on the Status of Endangered Wildlife in Canada (cosewic). The main cause of this listing has been attributed to loss of native prairie habitat. Presently, the committee on the Recovery of Nationally Endangered Wildlife (renew) of Canada is drafting a recovery plan for this species. Apart from this action, there has been little else done to aid the recovery of Sage grouse in Canada. The status of western subspecies of Sage grouse (Centrocercus urophasianus phaios) within the United States varies. In New Mexico, Arizona, British Columbia, Nebraska, and Oklahoma it is extirpated. Populations have been designated as secure (no federal ranking) in Montana, Wyoming and Idaho. Again, the extirpation of some of these populations can be attributed to loss of native prairie habitat (i.e. sagebrush habitat).