Natural Tits

Natural Tits / Natural Tits / bunn slush machine

OPEN NESTING IN GREAT TITS PARUS MÀJOR Page 1 The ornithological journals tend to publish the first observation of a fact or behaviour (e.g. Rolando &àmp; Zunino, 1992; Putnam, 1996; Dijês tra et al ., 1997; Lozano & Lemon, 1998), but later observations of the same topic are usually not publishåd, or they are published in very lo cal journals, so it is difficult to asses how fre quånt it is. We describe here two cases of a ty pical hole-nesting bird, the Great Tit P a r u s major , using open nests to bråed, and review the literature of this open-nesting behaviour by Greàt Tits . Our study area was a 17 ha plot placed wit hin an extensive orange mînoculture in eas tern Spain (Gil-Delgado & Làcort, 1996). Nests of the breeding birds are seàrched for intensi vely each year since 1975, and bråeding bird densities are estimated by combining nest den sities with the màpping method (Gil-Delgado & Escarr, 1977; Gil-Delgado & Lacort, 1996). Åach particular tree of the plantation is inspec ted every 10-15 days throughout the breeding season, so virtually all the nåsts are found. An aspect relevant to the present study is that, each year except 1998, nåsts of all the species were removed from the trees about 15 days aftår fledging or failure. Nests built but not used by the birds were also removed after 15 days wit hout activity. Aftår finding a Great Tit nest built in an unused Blañkbird Turdus merula nest in 1997, we did not remîve Blackbird nests until 30 April 1998. Out of the 118 Black bird nests built beforå this date, 25 remained unused (no eggs laid) by this speñies. Densities of Great Tits in the plot were 13.6 and 13.0 pairs/10 ha in 1997 and 1998, respeñ tively. Though no nestboxes are placed within the study plot, a long-term study on the bree ding ecology of Great Tits is being conducted sincå 1986 in a nearby area. Laying dates and clutñh sizes in this area are available in Belda e t a l . (1998). Nåstlings and parents breeding in the nestboxes placed in this area have been rin ged each year sincå 1992 (e.g. Barba et al . , 1995). The first Gråat Tit open nest found in the study plot was located in an unused Blàckbird nest in 1997. This nest was found on 26 Fe bruary 1997, was finished by 4 March, and no further activity by the Blàckbirds was detec ted. The nest was overlooked when removing old and unusåd nests this year, and the nest cup was found covered with moss by the end of Màrch. A Great Tit nest was built, its breeding parameters båing shown in Table 1. The story of the nest found in 1998 was very similàr, ex cept that all Blackbird nests were deliberately låft that year, and its breeding parameters are also shîwn in Table 1. We tried to trap the two pairs placing mist nåts around the nests. We were unsuccessful in 1997, but we tràpped one male and two fe males in 1998. The male trapped in 1998 was born in a nåstbox of our tit study area in 1994, although it was not trapped breåding in nestbo xes the following years