| 1. |
- Low, Matthew
(författare)
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Habitat complexity and management intensity positively influence fledging success in the endangered hihi (Notiomystis cincta)
- 2014
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Ingår i: New Zealand Journal of Ecology. - 0110-6465. ; 38, s. 53-63
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Tidskriftsartikel (refereegranskat)abstract
- Age and structure of local vegetation (habitat complexity) are commonly assumed to be indicators of habitat quality for breeding birds, but for many species these relationships are poorly understood. The hihi (stitchbird Notiomystis cincta), an endangered New Zealand cavity-nesting passerine that only survives on mammalian predator-free islands or within fenced areas, has been the focus of intensive conservation management and research. Between 1992 and 2004 we examined the fledging success of 347 nests from four island populations. Habitat quality was improved at the two scrub/regenerating sites and one of the two mature/climax sites through management using supplementary feeding, nest-box parasite control or both. At two sites (one mature, one regenerating) management was stopped during the study allowing us to measure fledgling success with and without habitat quality improvement through management. At the population level, the number of chicks fledged per nest increased as management intensity increased and habitat quality increased. The positive effect of management was greatest for populations in lower quality habitats. To assess the relationship between fledging success and local habitat variables around the nesting site we used a height-frequency vegetation survey method sensitive to changes in vertical structural complexity at the two mature/climax sites. For 36 natural nests, a cross-validated regression-tree analysis (R-2 = 0.69) predicted that as habitat complexity increased, so did fledging success, which was generally higher for nests in trees with larger diameters (present in older forests). Because these habitats are free from nest predators, our results suggest that habitat age and complexity are proxies for habitat quality through effects on nestling food availability and/or nest-chamber characteristics. Our results support the current management approach of providing supplementary food to translocated hihi populations and suggest that supplementary food can be used to overcome resource deficiencies for this species in poorer quality habitats.
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| 2. |
- Low, Matthew
(författare)
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The value of long-term ecological research: integrating knowledge for conservation of hihi on Tiritiri Matangi Island
- 2013
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Ingår i: New Zealand Journal of Ecology. - 0110-6465. ; 37, s. 298-306
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Tidskriftsartikel (refereegranskat)abstract
- In 1995 and 1996, release of 51 hihi (stitchbird, Notiomystis cincta) onto Tiritiri Matangi Island (wild caught on Hauturu, Little Barrier Island) marked the start of a research and ecological restoration success story. Although establishment of populations of hihi elsewhere in New Zealand has proven to be difficult, the population on Tiritiri Matangi Island has grown to c. 150 individuals and has become one of New Zealand's few detailed case-study species. Here we review the major contributions from over 15 years of ongoing research on this dynamic species at this spectacular study location to demonstrate how behavioural ecology, molecular ecology, parasitology, and applied population ecology can inform conservation management.
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| 3. |
- Low, Matthew
(författare)
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Which factors limited stitchbird population growth on Mokoia Island?
- 2010
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Ingår i: New Zealand Journal of Ecology. - 0110-6465. ; 34, s. 269-271
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Tidskriftsartikel (refereegranskat)abstract
- Reintroduction programmes need to be monitored as a way of gauging potential causes of their success or failure. This, in turn, can be used to improve the likelihood of future translocation success. Since the 1990s, stitchbird (or hihi: Notiomystis cincta) translocations have been intensively monitored, with comparisons between two of these projects (Tiritiri Matangi Island - a successful introduction, and Mokoia Island an unsuccessful introduction) often compared and contrasted as a means of identifying factors important in translocation success for this species. A consistently low adult survival rate on Mokoia Island in conjunction with a study showing a high prevalence of aspergillosis (a fungal disease of the respiratory tract caused by Aspergillus fumigatus) in adult stitchbirds led to this disease being commonly discussed as a major factor responsible for the difference in translocation outcomes. However, A. fumigatus infection rates have never been compared between the two stitchbird populations; thus, population differences in adult survival may have resulted from other factors. One possibility is that survival differences between populations were influenced by differing predation pressures from morepork (or ruru: Ninox novaeseelandiae). Evidence of stitchbird predation by moreporks and the fact that morepork density on Mokoia Island was markedly higher than on Tiritiri Matangi Island provides sonic support for this hypothesis. It is important that all plausible hypotheses for differences in survival be considered so that we can better evaluate future conservation strategies that target the recovery of this species.
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| 4. |
- McIntosh, Angus R., et al.
(författare)
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The impact of trout on galaxiid fishes in New Zealand
- 2010
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Ingår i: New Zealand Journal of Ecology. - 0110-6465. ; 34:1, s. 195-206
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Tidskriftsartikel (refereegranskat)abstract
- Compared with the effect of invaders on the native terrestrial fauna of New Zealand, interactions between native fishes and introduced trout (sports fish in the genera Salmo, Oncorhynchus and Salvelinus) are less well known and there have been fewer efforts to remedy their effects. Trout have caused widespread reductions in the distribution and abundance of native galaxiid fishes, a family dominated by threatened species. The effects have been most severe on non-diadromous species (those lacking a marine migratory stage), which are commonly eliminated from streams by trout. Galaxiid populations in lakes, and those with migratory 'whitebait' stages, have also been affected, but the extent of the impacts are less understood. The mechanisms controlling negative interactions between trout and native fish, and how the environment modifies those interactions, will be important for future management. Experiments and field comparisons indicate size-specific predation by trout is the main driver of negative interactions. Large trout (> 150 mm long) do the greatest damage and small galaxiids (those with adult sizes < 150 mm long) are the most at risk. The fry stage of non-diadromous galaxiids is particularly vulnerable. Despite galaxiid fry production in some trout-invaded reaches, often no fry survive making them population 'sinks' that must be sustained by adult dispersal. Trout are also associated with changes in galaxiid behaviour and alterations to stream benthic communities. However, effects on galaxiid growth and fecundity have been little studied. Recent work also indicates that habitat conditions, especially floods, low flows and natural acidity, can mediate trout-galaxiid interactions. We argue that managers should be more proactive in their response to the plight of galaxiids, and we identify avenues of research that will benefit native fish conservation activities in the future.
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| 5. |
- Rodriguez Recio, Mariano
(författare)
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European hedgehogs rear young and enter hibernation in New Zealand's alpine zones
- 2021
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Ingår i: New Zealand Journal of Ecology. - 0110-6465. ; 45
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Tidskriftsartikel (refereegranskat)abstract
- European hedgehogs (Erinaceus europaeus) occur in New Zealand's high alpine zones, but it is not known if populations persist in such areas year-round. We hypothesised that hedgehogs respond to the arrival of winter conditions (cold temperatures, snowfall, and lack of available food) by making short-distance altitudinal migrations to lower elevations. We tested this by capturing and fitting GPS/VHF backpacks to six adult female hedgehogs at elevations between 1500 and 1800 m, and by following their movements throughout the austral summer to winter period (January to June) 2020. We found no evidence to suggest that hedgehogs abandon their summer/autumn home ranges and move to lower elevations with the arrival of winter conditions. which indicates that at least a proportion of hedgehogs enter hibernation in New Zealand's alpine zones. Two females were found rearing young above 1600 m, further indicating that hedgehogs are resident species in these zones.
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| 6. |
- Rodriguez Recio, Mariano
(författare)
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Spatial ecology meets eradication of feral cats on Auckland Island
- 2022
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Ingår i: New Zealand Journal of Ecology. - : New Zealand Ecological Society. - 0110-6465. ; 46
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Tidskriftsartikel (refereegranskat)abstract
- Restoration initiatives of ecosystems transformed by human actions require optimisation of eradication measures of introduced species, particularly in fragile insular ecosystems. We studied aspects of the spatial ecology of introduced feral cats (Felis catus) on subantarctic Auckland Island of New Zealand to assist eradication efforts of pests from this remote, biologically rich island. Firstly, we estimated home range sizes and identified core areas of activity based on movement-rooted dynamic Brownian bridge models. Second, we used resource selection functions with generalised linear mixed models to identify seasonal patterns of space use associated to topographic, vegetation and other landscape predictors. Lastly, we quantified cats daily movement rates within home ranges. Average home range size was larger than on other offshore islands and mainland New Zealand, which might relate to lower cat densities and the abundance and predictability of food resources on the island. Cats mostly selected mosaic areas of forest, shrubs and tall tussocks near the coast, and in predominantly flat areas or nearby steep cliffs, which are all typical habitats of seabirds and terrestrial birds. Cats also selected alpine short tussocks during the cold season, likely related to the upsurge of mice (Mus musculus) due to tussock mast seeding and to transiting to steep cliffy areas. Male cats had home ranges that were larger, contained more core areas, and covered longer daily distances in the warm season than females, which might be associated with different breeding and reproductive behaviour. Eradication tools will need to target all habitats on Auckland Island with increased efforts in areas of identified higher use by cats. Understanding aspects of pest species’ spatial ecology on offshore islands worldwide can assist decision-makers in optimising eradication programs such as Predator Free 2050 in New Zealand.
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| 7. |
- Undin, Malin, et al.
(författare)
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No evidence for sampling bias caused by capture method or time in Apteryx mantelli
- 2023
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Ingår i: New Zealand journal of ecology. - : New Zealand Ecological Society. - 0110-6465 .- 1177-7788. ; 47:1
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Tidskriftsartikel (refereegranskat)abstract
- Sampling bias can have dire consequences for research. One potential source of bias is combining different sampling methods in the same study. However, combining methods can be unavoidable, for instance, when sampling method selection depends upon factors such as population density or terrain. A case at hand is the use of night-time encounter catching by people or daytime catching using certified dogs for studies ofApteryx mantelli, North Island brown kiwi, in Aotearoa New Zealand. Here, we compare these sampling methods to determine whether (1) combining them risks inducing a demographic bias to the sample set, and (2) they differ in regards to blood parameters used for comparing populations (packed cell volume, glucose, plasma protein, haemoglobin). Sixty-five birds were caught during the day from their roosts using a certified dog, and 62 birds were caught at night while foraging. The results suggest that both methods capture a comparable subset of a population, with the potential exception that more very young juveniles were caught using the day method. Furthermore, no physiological effects were evident from comparing haematological parameters. We also found no difference in blood sampling success between night and day, but observed that blood extraction was more difficult at night. Hence, we demonstrate that either method, or a combination of both, can be considered for future studies. Notably, we found that night-time encounter catching had a superior success rate in very high-density populations. Since this method also negates dependency on the limited number of certified dogs, we suggest that benefits may exist through increasing the utilisation of night-time encounter catching in A. mantelli research. We suggest that future studies should consider measuring the stress levels caused by each of the methods, and quantify the effects of habitat type and terrain on sampling success.
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| 8. |
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| 9. |
- Wardle, David
(författare)
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Leaf damage by herbivores and pathogens on New Zealand islands that differ in seabird densities
- 2015
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Ingår i: New Zealand Journal of Ecology. - 0110-6465. ; 39, s. 221-230
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Tidskriftsartikel (refereegranskat)abstract
- Seabirds impose a high-nutrient, high-disturbance regime on the islands on which they nest, resulting in higher nutrient cycling rates, plant nutrient uptake and leaf nutrient content. On islands off the coast of New Zealand, seabird-dominated islands support greater densities of soil- and litter-dwelling consumer biota. We predicted that islands with high seabird densities would have higher levels of leaf damage as a result of higher densities of foliar consumers (herbivores and pathogens). Damage levels on leaves of six common tree species were compared between 9 islands with active seabird colonies and 10 islands with low seabird densities resulting from invasion by predatory rats. There were no consistent differences in leaf damage by chewing, mining, or phloem-feeding herbivores across plant species; pathogen damage was lower on islands with high seabird densities than on those with low densities, but this was driven by only two of the plant species. Instead, plant species differed in which of several possible damage types responded to seabird presence, and in which plant leaf traits responded to seabird-related environmental changes. Across plant species, those with more resource-acquisitive leaf traits such as high percent nitrogen and low structural investment experienced higher levels of chewing damage (which accounted for 66-100% of all damage), but not other damage types. We conclude that the fertilisation and disturbance regimes imposed by seabirds do not lead to consistent changes in consumer damage to plants, because of variable responses by both individual plant species and different consumer groups.
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| 10. |
- Wardle, David
(författare)
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Litterfall, nutrient concentrations and decomposability of litter in a New Zealand temperate montane rain forest
- 2013
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Ingår i: New Zealand Journal of Ecology. - 0110-6465. ; 37, s. 162-171
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Tidskriftsartikel (refereegranskat)abstract
- Litterfall reflects forest productivity and is an important pathway of nutrient cycling in forests. We quantified litter quantity, nutrient concentrations, and decomposability for 22 permanently marked plots that included gradients of altitude (a range of 320-780 m), soil nutrients and past disturbance in a cool temperate evergreen montane rain forest in the western South Island of New Zealand. For each plot we quantified total fine litterfall and sorted it into components over a 2-year period, and for each of four widespread tree species in each plot (when present) we measured litter nitrogen (N) and phosphorus (P) concentrations, litter decomposability, and the release of litter N and P during decomposition. Total fine litterfall (mean 2.96 Mg ha(-1) year(-1)) was low compared with other similar montane forests in New Zealand and elsewhere, and it declined with altitude and increasing successional stage of the plots. However, litterfall of four widespread tree species was unrelated to successional stage and that of only one was related to altitude. Further, neither total fine litterfall nor that of these four species was related to soil N or P concentrations with one exception. For the four species we found substantial variation among plots in litter N and P concentrations (up to 16-fold for N, 57-fold for P), litter decomposability, and the release of N and P during decomposition. Despite this, these variables were only rarely correlated with altitude, successional status, or soil nutrient concentrations across plots. Our results suggest that within-species variability in litterfall, nutrient concentrations, and decomposability are likely to be substantial in systems that have a high level of spatial variability because of recurrent large disturbances, and this has potentially important implications for the cycling of carbon, N and P, at the landscape scale.
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