Letteratura scientifica selezionata sul tema "Hemiphaga novaeseelandiae"

Members of the genus Treron (Columbidae) are widely distributed in southern Asia and the Indo-Malayan Region but their relationships are poorly understood. Better knowledge of the systematic status of this genus may help studies of historical biogeography and taxonomy. The complete mitochondrial genome of T. curvirostra was characterized, a first for the genus. It is 17,414 base pairs in length, containing two rRNAs, 22 tRNAs, 13 protein coding genes (PCGs), and one D-loop with a primary structure that is similar to that found in most members of Columbidae. Most PCGs start with the common ATG codon but are terminated by different codons. The highest value of the Ka/Ks ratio within 13 PCGs was found in ATP8 with 0.1937, suggesting that PCGs of the mitochondrial genome tend to be conservative in Columbidae. Moreover, the phylogenetic relationships within Columbidae, which was based on sequences of 13 PCGs, showed that (T. curvirostra + Hemiphaga novaeseelandiae) were clustered in one clade, suggesting a potentially close relationship between Treron and Hemiphaga. However, the monophyly of the subfamilies of Columbidae recognized by the Interagency Taxonomic Information System could not be corroborated. Hence, the position of the genus Treron in the classification of Columbidae may have to be revised.

This study investigated the potential risks of using 1080 apple bait for possum control on nontarget species Trials were conducted using captive native birds at Orana Park and honeybees (Apis mellifera) at Halswell to determine whether these species would feed on nonpoisonous apple baits Bird species were kaka (Nestor meridionalis) kea (Nestor notabilis) kakariki (Cyanoramphus sp) silvereye (Zosterops lateralis) weka (Gallirallus australis) and kereru (Hemiphaga novaeseelandiae) Kaka kea kakariki and silvereye preferred to feed on apple bait over carrot bait spending 74100 of their feeding time on the apple bait Honeybees were not attracted to the apple bait It is concluded that there could be a greater risk to native birds when apple baits are used for possum control compared to the risk associated with using carrot bait Consequently it is recommended that aerial application of apple should not be undertaken and that apple baits should be used in bait stations only

My research investigates seed dispersal, post-dispersal stages, and dispersal vector behaviour in native New Zealand forest canopy tree species that have large fruit by asking: (i) What are the local seed ‘shadows’ (distributions) and seedling patterns in Prumnopytis ferruginea (miro, Podocarpaceae, dioecious) and Vitex lucens (puriri, Verbenaceae, hermaphroditic), for which Hemiphaga novaeseelandiae, the New Zealand Pigeon (kereru, Columbidae), is the keystone agent of dispersal? (ii) What are the effects of kereru densities on the quantity of dispersed miro and puriri seeds, and do kereru preferentially disperse large and/or viable seeds? (iii) Are other native large-fruited tree species, which depend on kereru, being actively dispersed or regenerating locally? (iv) Do recruitment patterns in miro and puriri demonstrate seedling ‘escape’, and if so, are there associated advantages? (v) How are the parameters of long distance seed dispersal kernels (probability density functions) in simulated miro and puriri forests affected by changes in kereru densities and spatial patterns of trees? Local seed distributions in miro and puriri were anisotropic and were described best by gamma and Weibull (i.e. leptokurtic) probability density functions. Seed shadows across both seasons had less steep slopes in Hunua miro compared with Waitakere miro, but increased production of actively dispersed depulped seeds did not increase dispersability. In both tree species, passive dispersal of seeds with mesocarp occurred mostly to the north and occasionally to the south, but active dispersal was less defined. Canopy openness, canopy size, and fruit production did not influence local mean dispersal distances in both tree species. Seedling distributions were inversely spatially concordant with seed patterns (demonstrating escape) only in miro in the first season. Seedlings were confined to north to north-easterly sectors for both tree species in both seasons, which mirrored the direction of passive seed rain. Seedling abundance for all miro trees decreased by c. 56% over 21 months, but there was lower seedling loss overall for puriri at c. 25%. Seedling survival and growth rates in either tree species were not significantly different whether under or away from the canopy. Kereru counts and densities were not significantly different between regions. There was a marginally significant correlation between kereru densities and the percentage of actively dispersed depulped seeds in seed shadows across both tree species in season one only. For puriri and miro trees overall, actively dispersed depulped seeds were significantly longer than seeds from passively dispersed intact fruit, demonstrating vector preference for larger fruit. Removal of miro fruit and seeds by mammals was higher overall at Waitakere compared with Hunua; Waitakere puriri had higher predation overall than Wenderholm puriri, and higher predation of actively dispersed depulped seeds vs. intact fruit. Actively dispersed depulped miro seeds had significantly lower endosperm integrity rates than seeds from passively dispersed intact miro fruit. iv In the study regions, miro, puriri, Corynocarpus laevigatus (karaka), Beilschmiedia tarairi (taraire), and Beilschmiedia tawa (tawa) trees were regenerating locally since they all had seedlings of their own species growing under their own canopies. There was also satisfactory active dispersal since the observed deviations from expected values of the presence of seedlings of other large-fruited tree species were generally significant. There were preferential patterns of seed dispersal: taraire seedlings were found most often under puriri trees and tawa seedlings were found most often under female miro trees. However, there was an absence of tawa seedlings under karaka trees, karaka seedlings below female miro trees, and only a very few miro seedlings under taraire trees. Miro seedlings were consistently absent under puriri and karaka trees, and no taraire seeds were dispersed at female miro trees in Waitakere. At Pelorus Bridge, Marlborough, miro seeds were preferentially dispersed under a miro tree and to a lesser degree under a hinau tree, across five seasons. There was virtually no active dispersal of tawa or hinau seeds under their own canopies or under co-fruiting tree species during this time. A rimu tree received only a few miro or tawa seeds, and rimu seeds occurred only in small numbers under a female miro and tawa tree. Kahikatea and matai were the main actively dispersed species under trees. Damage of bird-dispersed depulped seeds by mammals was high for tawa and low in miro. Experiments using an original spatially-explicit in silico simulation model showed that scale (mean dispersal distance), shape (kurtosis-1), and percentage of seeds dispersed beyond the nearest fruiting tree neighbour all decreased with increasing tree aggregation in simulated puriri and miro forests. There were no significant changes in the parameters when kereru density changed, except in some puriri forests at high kereru densities. Total mass of dispersed seeds increased with increasing kereru density, but the % of seeds dispersed beyond the nearest fruiting tree neighbour did not vary appreciably. My research suggests that low kereru densities may reduce the quantity of dispersed seeds and the rates of dispersal of larger seeds, especially if alternative dispersers are not available. Kereru are particularly important for dispersal in miro, since dioecious trees may be more susceptible to dispersal failure than co-sexual species.
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The present study is part of the Kaupapa Kereru Programme. The main aim of the programme is to increase the numbers and range of kereru (Hemiphaga novaeseelandiae) on Banks Peninsula. Home ranges, movements, diet and habitat use of 15 kereru captured in Hinewai Reserve, Banks Peninsula, were investigated from February 2005 to February 2006. Hinewai Reserve is the largest tract of regenerating native forest in a highly modified urban-rural landscape. Phenology of 11 plant species predicted to be key kereru foods, was studied to determine the pattern of food availability in Hinewai Reserve. Twelve radio-tagged kereru resided in the Hinewai Reserve study site (Otanerito Valley and Sleepy Bay) and three resided in Akaroa. Ripe fruit was available from January to August; the height of the fruiting season was in autumn. The bulk of new leaf growth occurred in spring and early summer although new leaves were available on broom and tree lucerne year round. Peak flowering occurred in spring. Kereru in Akaroa ate a total of 21 plant species; six of these species were native and 15 introduced. Kereru in the Hinewai Reserve study site ate a total of 26 plant species; 20 of these species were native and six introduced. Fruit was preferred when readily available. Native fruit appeared to be preferred over fruit of introduced species in Akaroa, where both types were available. New foliage of introduced legumes and deciduous species appeared to be preferred over new foliage of native species at both sites during winter and spring. These species were important food sources prior to the breeding season and may be selected specifically for their nitrogen and protein content. Food is currently not a limiting factor for kereru survival or reproductive success. Considerable variation in the use and preference of vegetation types of individual kereru made it difficult to identify trends in habitat selection. Use and preference for many vegetation types was seasonal; this was certainly because of the availability of food species included in or close to these vegetation types. Overall, native vegetation communities were used more than communities dominated by introduced species and forest communities were used more than non-forest communities. Kanuka (Kunzea ericoides) was used most often for non-feeding activities and 67% of observed nests were built in kanuka. Annual home ranges and core areas in the Hinewai Reserve study site (mean of 15.9 and 2 ha respectively) were significantly larger than those found in Lyttelton Harbour, Banks Peninsula in previous research (mean of 8 and 0.08 ha respectively). Home ranges were larger when fruit was eaten, than when no fruit was eaten indicating that kereru are more sedentary when feeding on foliage. Kereru from the Hinewai Reserve study site made no excursions >5 km and no daily movements >2 km. Kereru from Akaroa and Sleepy Bay travelled into Otanerito Valley to feed on horopito in autumn, indicating that there may have been a lack of fruit in their local areas during autumn. No kereru in Otanerito Valley travelled outside of the valley. The distribution of high quality food sources is likely to have caused the observed differences in home range and core area size between localities. Kereru in Lyttelton Harbour may have been restricted to small patches of high quality resources in a study area consisting largely of unsuitable habitat. In Hinewai Reserve, high quality resources were spread over larger areas and were more uniformly distributed. The density of kereru was unknown at both study sites, and this confounded assessment of habitat quality. However, it is likely that the Hinewai Reserve study site would support a higher number of kereru. The main factor limiting population growth in the present study was failure of nests at the egg and chick stage. The fledge rate was 17%. Two of fifteen adult kereru died. Control of predators should be the first aspect of management that is focused on, and will almost certainly increase reproductive success of kereru and loss of breeding adults. As the population of kereru on Banks Peninsula increases due to predator control in existing kereru habitat, food may become a limiting factor. Habitat can be improved for kereru by planting a diverse range of plant species that provide food year-round. Native fruiting species are greatly recommended for habitat enhancement and should be selected so that fruit is available for as much of the year as possible. Native and introduced legumes should also be made available as foods for winter and spring. As most land on Banks Peninsula is privately owned, co-operation and enthusiasm of the community is critical for successful management. Information and support needs to be given to landowners wishing to enhance their properties for kereru.

The decline of kereru (Hemiphaga novaeseelandiae) may limit dispersal of large-seeded plants in New Zealand, but the consequences of this are unknown. I determined kereru disperser effectiveness by modelling seed dispersal distances (using seed retention times and movement patterns). Mean seed retention time was significantly longer for larger-seeded species, ranging from 37-181 minutes. Wild radiotracked kereru were sedentary, remaining at one location for up to 5.25 hours. The mean flight distance was 77 m and the maximum was 1, 457 m. Estimated mean seed dispersal distances for tawa (Beilschmiedia tawa), puriri (Vitex lucens), and fivefinger (Pseudopanax arboreus) were 95, 98, and 61 m respectively. Kereru dispersed 66-87% of ingested seeds away from the parent tree, with 79-88% of seeds dispersed <100 m and < 1% dispersed over 1,000 m. In a field seed-fate experiment, "pre-human" conditions (cleaned seeds, low density, away from parent, and protected from mammals) increased survival compared to "post-human" conditions (whole fruits, high density, under parent, not protected) for both taraire (Beilschmiedia tarairi; 15% vs. 2% survival to one year respectively) and karaka (Corynocarpus laevigatus; 60% vs. 11% to two years, respectively). Fruit diameter varied considerably within karaka, taraire, and tawa, although theoretically not enough for them to be swallowed by other birds. Nevertheless, other birds are reported to occasionally take fruits of nearly all large-seeded species. Small tawa seeds produced smaller seedlings in the glasshouse; therefore selection of only smaller seeds by alternative dispersers may negatively affect tawa recruitment. Kereru are generally not gape-limited, and fruit size preferences were independent of mean fruit size. Kereru provide effective dispersal by moving most seeds away from the parent, and enhancing seed and seedling survival. Therefore, both dispersal failure and introduced mammals negatively affect the regeneration of large-seeded trees in New Zealand.