{"id":470,"date":"2017-10-13T12:00:38","date_gmt":"2017-10-13T12:00:38","guid":{"rendered":"http:\/\/wordpress.viu.ca\/biol325\/?p=470"},"modified":"2017-12-02T03:44:56","modified_gmt":"2017-12-02T03:44:56","slug":"courtship-behaviour-and-diving-displays-of-annas-hummingbird","status":"publish","type":"post","link":"https:\/\/wordpress.viu.ca\/biol325\/2017\/10\/13\/courtship-behaviour-and-diving-displays-of-annas-hummingbird\/","title":{"rendered":"Courtship Behaviour and Diving Displays of Anna’s Hummingbird"},"content":{"rendered":"

Anna\u2019s Hummingbird belongs to the genus Calypte<\/em>, which also includes the species Costa\u2019s Hummingbird. Both C.<\/em> anna<\/em> and C.<\/em> costa<\/em> display courtship behaviour that includes diving displays. The courtship behaviour of these hummingbirds has been researched extensively as it is incredibly interesting!<\/p>\n

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A male adult Anna’s hummingbird perched and ready to learn about diving displays! [Link<\/a>]<\/p><\/div>
\nObservations done by Stiles1<\/sup> & Clark2<\/sup> defined these activities. It was noticed that there is an initial contact made by the female in which she will fly into the male\u2019s territory and try to feed.1<\/sup> While the female is in the males territory she will evaluate its quality. She will then be approached by the male whereby he will proceed to sing to her with his gorget flared, perform a \u201cshuttle\u201d display, and then partake in a series of outstanding diving displays.3<\/sup> These performances may result in copulation if the male is lucky! \u00a0The \u201cshuttle\u201d display is described as a back-and-forth motion above the female, while producing a high-intensity song.1<\/sup> This display is said to be the most crucial part of courtship! The diving display consists of the male rising approximately 30 m and then carrying out a high-speed swooping dive over the female.3<\/sup><\/p>\n

Overall C.<\/em> anna<\/em> can produce a variety of noises, such as a chip note, a chatter, a song, and a sonation from diving. The chip note is described as a low-intensity \u201cshort, sharp, dry, \u2018tzin<\/em>\u2019\u201d1<\/sup> which represents basic interaction amongst all members. The chatter resembles buzzy, harsh, high-intensity notes to signify aggression1<\/sup>, often given by territorial males or females guarding their nest. The song produced by C. anna<\/em> is highly complex and structured. Males rely heavily on their song in breeding territories.1<\/sup><\/p>\n

The chip, chatter and song all rely on vocal mechanisms from the syrinx. It was once thought that the sound created from the dive display was vocal as well, however through multiple studies2,3<\/sup> with the use of high-speed video it has been proven the sound is a mechanism of the outermost tail feathers.2<\/sup> The dive was analyzed extensively and split into 5 stages.2<\/sup> The first stage begins with the hummingbird diving with a trajectory towards the sun. The diving male will propel himself downwards with wings flapping at a frequency of approximately 55.5 \u00b1 1.72 Hz. In stage 2 the male ceases the flapping and tucks in his wings. In stage 3 the wings are spread to glide, transitioning into stage 4 in which the male reaches the bottom of the dive and will swiftly spread his tail, achieving the diving sonation. The final stage of the dive involves the male flapping his wings once and shutting the tail.<\/p>\n

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An illustration showing the location of the outer R5 feather on a male Anna’s. [Link<\/a>]<\/p><\/div>By comparing the sound produced with the event of the tail opening, it was determined that the tail does in fact produce the sound.2 <\/sup>Specifically, it is the result of air flowing over the R5 outermost feather causing fluttering of the trailing vane. A study2<\/sup> was conducted whereby the R5 feathers were removed or trimmed and the birds performed the dive display. Removing the R5 feather resulted in the elimination of the dive sound. It was also evident in this study that faint changes in the shape of the feather can tune the frequency of sound generated when the tail is spread.<\/p>\n