科研之友
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摘要
Global declines in cuckoo numbers have been variously attributed to reduced prey availability; changes in their hosts' ranges; or climate-induced changes. We used data from two Southern African Bird Atlas Projects to determine whether migrant cuckoo species breeding in South Africa, Lesotho and Swaziland have experienced range shifts during the past 25 years; and whether such changes corresponded to shifts in host species distribution. Changes in presence/absence data indicated that of the nine cuckoo species found breeding in this region, six showed reductions in range (African Cuckoo, African Emerald Cuckoo, Diederik Cuckoo, Great Spotted Cuckoo, Jacobin Cuckoo and Red-chested Cuckoo); two are expanding (Black Cuckoo and Levaillant's Cuckoo) and one remains stable (Klaas's Cuckoo). Occupancy modelling of these data indicated that the host ranges of only four of the nine species (Great Spotted Cuckoo, Klaas's Cuckoo, Levaillant's Cuckoo and Red-chested Cuckoo) predicted cuckoo distribution in the first instance. Of these, only in Levaillant's Cuckoo is range expansion related to changes in the range of its sole known host species in the region, the Arrow-marked Babbler. These results imply that factors other than changes in the ranges of their hosts appear to be driving the range reductions observed in six southern African cuckoo species.
- 出版日期2017
