Tropical Cyclone Heta or Hunting by People Responsible for Decline of the Lupe ( Ducula pacifica ) ( Aves : Columbidae ) Population on Niue during 1994 – 2004 ? 1

On 6 January 2004, Tropical Cyclone Heta devastated much of the South Pacific island nation of Niue. The forest suffered extensive damage, particularly to the north-western sector, with many trees uprooted and others stripped of branches and foliage. Even though some patches of forest in the southeast sustained little damage, many lupe (Pacific pigeon, Ducula pacifica) and kulukulu (purple-crowned fruit dove, Ptilinopus porphyraceus) entered eastern villages in search of food and water after the cyclone, a very unusual behavior. This paper details our findings from a survey of some of Niue’s forest birds carried out during September 2004 and compares these with results from a similar survey in September 1994. Five-minute point count data, an index of conspicuousness, from three transects showed that heahea (Polynesian triller, Lalage maculosa) were more abundant in 2004 than in 1994, that the results were variable from transect to transect for miti (Polynesian starling, Aplonis tabuensis) and kulukulu, but that significantly fewer lupe were detected along all three transects in 2004 than previously. We tentatively suggest that the decline in the lupe population was caused mainly by unsustainable human hunting during 1994–2004, rather than mortality caused by the cyclone. Tropical cyclones and hurricanes can cause severe damage to forests, resulting in the stripping of leaves, flowers, fruits and seeds; breaking of trunks and branches; and toppling of trees (Wiley and Wunderle 1993, Bellingham et al. 1994, Everham and Brokaw 1996, Burslem et al. 2000). The impact of such storms can be quite variable on both forests and birds. For example, areas of undamaged forest in gullies and valleys can occur within 200 m of areas where many trees on exposed ridges and hills have been toppled and those still standing have been stripped of foliage (Varty 1991, Wunderle 1995, 1999, Robertson and Saul 2007). High winds and heavy rainfall associated with cyclones and hurricanes can kill birds, but studies have shown that it is the indirect effects of such storms that usually have the most profound and long-lasting impacts on bird populations (Varty 1991, Wauer and Wunderle 1992, Wiley and Wunderle 1993, Wunderle 1995, Prather and Smith 2003, Tejeda-Cruz and Sutherland 2005, Robertson and Saul 2007). These effects include loss of food supplies, foraging substrates, and nest or roost sites and increased vulnerability to predation, including by people (Craig et al. 1994, Wunderle 1995). Before trees and shrubs have recovered, birds may respond by changing their diets, locations, habitats, and timing of breeding (Varty 1991, Wunderle et al. 1992, Wiley and Wunderle 1993, Wunderle 1995). In Pacific Science (2008), vol. 62, no. 4:461–471 : 2008 by University of Hawai‘i Press All rights reserved 1 This work was approved by the Government of Niue and funded by the United Nations Development Programme via its ‘‘Enabling Activity on Biodiversity’’ project, and the New Zealand Department of Conservation (Science Investigation no. 3779). Manuscript accepted 7 December 2007. 2 Corresponding author: Research, Development, and Improvement Division, Department of Conservation, P.O. Box 10-420, Wellington 6143, New Zealand (e-mail: [email protected]). 3 David Butler Associates Ltd., 588 Brook Street, Nelson 7010, New Zealand. 4 Research, Development, and Improvement Division, Department of Conservation, P.O. Box 13-049, Christchurch 8141, New Zealand. general, short-term studies have shown that population declines of nectarivorous, frugivorous, and granivorous species after such destructive storms are more prevalent than those of insectivorous and omnivorous species (Askins and Ewert 1991, Waide 1991, Wunderle et al. 1992, Wiley and Wunderle 1993, Wunderle 1995, Tejeda-Cruz and Sutherland 2005). This is to be expected given that flower and fruit production often does not eventuate for several months after a cyclone or hurricane (Wunderle et al. 1992), whereas some arthropod populations either are unaffected by such storms or have quick recovery rates (Wolcott 1932, Wiley and Wunderle 1993). Tropical Cyclone Heta, henceforth referred to as Cyclone Heta, passed over the South Pacific island of Niue on 6 January 2004. During the cyclone, winds in excess of 270 km/hr (winds equivalent to hurricane 3 strength) ravaged Niue for about 5 hr, and a mountainous storm surge battered the west coast. The main settlement, Alofi, and the villages of Makefu, Tuapa, Namukulu, and Hikutavake (Figure 1) were all seriously affected. The combination of a high spring tide, cyclone travel direction, wind velocity and spiral direction, and a sloping seabed combined to maximum effect to produce a sea surge estimated at 50 m. This overtopped the cliffs and, in some areas pushed seawater 100 m inland, devastating everything in its path. In addition to the loss of human life and property that resulted, serious damage was done to Niue’s forest, particularly on the northern and western sides of the island. If not blown over, most trees and shrubs were stripped of leaves, flowers, fruit, and thin branches, and subjected to salt spray. The cyclone was followed by several days of intense heat, with no rain. After the cyclone, some fires used to clear areas of land for gardens got out of control and destroyed forest because of the considerable volume of flammable material produced by the cyclone that remained on the ground (M. Newfield, pers. comm.). Although Cyclone Heta and the drought that followed immediately afterward killed some wildlife, of more concern was the survival of forest-dwelling species during the subsequent period of several months when few flowers and fruit were available. Species of concern included the peka (Tongan flying fox, Pteropus tonganus), lupe (Pacific pigeon, Ducula pacifica), kulukulu (purple-crowned fruit dove, Ptilinopus porphyraceus), miti (Polynesian starling, Aplonis tabuensis), and hega (blue-crowned lorry, Vini australis). In late January, sprouting of foliage on defoliated trees was evident, and reasonable numbers of most forest bird species were seen in lessaffected forest areas (Butler 2004). This allayed initial concerns for bird population survival. However, many peka, lupe, and kulukulu on the eastern side of the island entered villages in search of food and water, a very atypical behavior. In response to what was obviously a crisis for the birdlife of Niue, the Government of Niue provided funds for a program, coordinated by Misa Kulatea, to provide food and water at feeding stations. In addition, because bats and birds entering villages were vulnerable to predation by dogs, cats, and people, some peka and lupe were taken into captivity, with the intention of releasing them once natural food sources became readily available again. After his assessment of the impacts of Cyclone Heta in late January 2004 (Butler 2004), D.J.B. urged the Government of Niue to conduct more in-depth surveys of the flora and fauna. As a result, a survey of some of Niue’s forest birds was carried out during 3– 19 September 2004. This paper details the findings from the survey and compares the results with those from a survey in September 1994 using the same methodology (Powlesland et al. 2000). materials and methods