Do population indicators work? Investigating correlated responses of bird populations in relation to predator management

Using population indicators to evaluate conservation achievements is widely practised, yet seldom empirically tested. If populations are consistently correlated in response to a shared ecological driver, the indicator species approach can be used as a cost-effective, ecologically-based shortcut to measuring the effects of conservation management. Long-term monitoring of forest bird populations associated with mammalian pest control programmes in New Zealand provides a useful framework for testing the population indicator species concept. We evaluated population trends in 21 bird species vulnerable to predation by introduced mammals (primarily mustelids and rodents) at managed and unmanaged beech (Nothofagus) forest sites. Correlated population trends between species pairs were detected at individual sites. However, neither positive nor negative correlations in species trends could be predicted by life history traits and predator management did not produce consistent, correlated population trends among sites. Our results do not support the use of a population indicator approach to management and reporting for forest birds in New Zealand. Relationships between purported indicator taxa and other species need to be understood for various management scenarios before population indicators can be confidently applied to measuring conservation achievement.     

Large‐scale pest control in New Zealand beech forests

In 2014, baits laced with the poison sodium fluoroacetate (1080) were sown over 694 000 ha of mostly native beech forests in New Zealand to control rats, stoats and possums – a landscape‐scale pest control programme called ‘Battle for our Birds’. This large pest control operation was necessitated by the mast seeding of beech trees which led to irruptions of rodent and stoats which were predicted to lead to decreases in vulnerable native wildlife. In this article, we describe why and how this extensive pest control programme was developed and implemented. We describe the seedfall monitoring that was used to determine the need for large‐scale rodent and stoat control and the response of these predators to this control. We also provide a summary of the bird monitoring that was undertaken to demonstrate the effectiveness or otherwise of the programme.     

Responses of kukupa (

The kukupa or New Zealand pigeon (Hemiphaga novaeseelandiae) is gradually declining on the New Zealand mainland, due mostly to predation by introduced pest mammals including ship rats (Rattus rattus) and brushtail possums (Trichosurus vulpecula). We report on a co-operative project between Maori landowners, the Department of Conservation, and Manaaki Whenua–Landcare Research researchers to restore a Northland kukupa population and to examine kukupa nesting success in relation to pest abundance. Ship rats and possums were targeted by trapping and poisoning throughout Motatau Forest (350 ha) from 1997 to 1999; only possums were targeted in 2000. All 13 kukupa nests located before pest control started in late 1997 failed at the egg stage, but all seven nests located in 1998–99 successfully fledged young when trapping and tracking indices of possums and ship rats were less than 4%. After pest control, counts of kukupa and some other bird species increased at Motatau compared with counts in a nearby non-treatment block, suggesting numbers of adult kukupa can be increased in small forest areas by intensive pest control. This increase is due at least partly to increased nest success. Evidence from time-lapse video cameras, sign remaining at nests, and nest success rates under different pest control regimes suggest both ship rats and possums are important predators at kukupa nests.     

Predation and other factors currently limiting New Zealand forest birds

Holdaway (1989) described three phases of historical extinctions and declines in New Zealand avifauna, the last of which (Group III, declining 1780?1986) was associated with European hunting, habitat clearance, and predation and competition from introduced European mammals. Some forest bird species have continued to decline since 1986, while others have increased, usually after intensive species-specific research and management programmes. In this paper, we review what is known about major causes of current declines or population limitation, including predation, competition for food or another resource, disease, forest loss, and genetic problems such as inbreeding depression and reduced genetic variation. Much experimental and circumstantial evidence suggests or demonstrates that predation by introduced mammals remains the primary cause of declines and limitation in remaining large native forest tracts. Predation alone is generally sufficient to explain the observed declines, but complex interactions between factors that vary between species and sites are likely to be the norm and are difficult to study. Currently, the rather limited evidence for food shortage is mostly circumstantial and may be obscured by interactions with predation. Climate and food supply determine the number of breeding attempts made by herbivorous species, but predation by introduced mammals ultimately determines the outcome of those attempts. After removal of pest mammals, populations are apparently limited by other factors, including habitat area, food supply, disease or avian predators. Management of these, and of inbreeding depression in bottlenecked populations, is likely to assist the effectiveness and resilience of management programmes. At the local or regional scale, however, forest area itself may be limiting in deforested parts of New Zealand. Without predator management, the number of native forest birds on the New Zealand mainland is predicted to continue to decline.     

Enhanced niche opportunities: can they explain the success of New Zealand's introduced bird species?

Aim  The niche hypothesis could explain why some species introduced to new locations reach higher densities than in their native range: it posits that the new environment provides more abundant or higher quality resources or habitat, a more suitable physical environment or both. We investigate whether 11 bird species occur at higher densities in their introduced range than in their native range and whether the differences can be explained by the availability of preferred habitat or the suitability of climatic conditions in their introduced range relative to their native range.
Location  South Island, New Zealand (the introduced range); UK (the native range).
Methods  We first develop a series of models that accurately predict the density of 11 bird species at 54 UK farmland sites, which are closely matched to our New Zealand sites, from habitat and climatic variables. We then use these models to predict the density of the 11 species at 54 New Zealand farmland sites and compare the predicted and observed values.
Results  Actual densities at New Zealand sites were on average (median) 22 times (range: 1–6361) higher than predicted from the UK models and similarly higher than actually observed at comparable UK sites. Habitat and climatic variables can accurately predict bird densities in the UK but grossly underestimate densities for all species except Turdus merula in New Zealand.
Main conclusions  These findings indicate that factors other than the measured habitat and climatic variables must differ between the two regions and explain the much higher densities of New Zealand birds. We suggest that introduced birds, other than T. merula , in New Zealand may still experience enhanced niche opportunities due to greater availability of higher quality resources within habitats, release from natural enemy regulation, less exposure to extreme weather events, particularly during winter, or some combination of these processes.     

Connecting soundscape to landscape: Which acoustic index best describes landscape configuration?

Soundscape assessment has been proposed as a remote ecological monitoring tool for measuring biodiversity, but few studies have examined how soundscape patterns vary with landscape configuration and condition. The goal of our study was to examine a suite of published acoustic indices to determine whether they provide comparable results relative to varying levels of landscape fragmentation and ecological condition in nineteen forest sites in eastern Australia. Our comparison of six acoustic indices according to time of day revealed that two indices, the acoustic complexity and the bioacoustic index, presented a similar pattern that was linked to avian song intensity, but was not related to landscape and biodiversity attributes. The diversity indices, acoustic entropy and acoustic diversity, and the normalized difference soundscape index revealed high nighttime sound, as well as a dawn and dusk chorus. These indices appear to be sensitive to nocturnal biodiversity which is abundant at night in warm, subtropical environments. We argue that there is need to better understand temporal partitioning of the soundscape by specific taxonomic groups, and this should involve integrated research on amphibians, insects and birds during a 24 h cycle. The three indices that best connected the soundscape with landscape characteristics, ecological condition and bird species richness were acoustic entropy, acoustic evenness and the normalized difference soundscape index. This study has demonstrated that remote soundscape assessment can be implemented as an ecological monitoring tool in fragmented Australian forest landscapes. However, further investigation should be dedicated to refining and/or combining existing acoustic indices and also to determine if these indices are appropriate in other landscapes and for other survey purposes.     

Attraction of the invasive social wasp,Vespula vulgaris,by volatiles from fermented brown sugar

The introduction of invasive social wasp species of the genus Vespula (Hymenoptera: Vespidae) to New Zealand has caused a major ecological problem, particularly in the beech forests (Nothofagus spp.) of the South Island, where they have destabilized the native bird and invertebrate biodiversity. New attractants are under investigation as part of a search for pest management solutions. Fermenting brown sugar has been previously reported as a social wasp attractant. This work was undertaken to identify compounds from fermented brown sugar attractive to social wasps. Raw fermented brown sugar was confirmed to be attractive in a field trial and 10 chemical compounds present in the headspace were positively identified by coupled gas chromatography‐mass spectrometry and synthetic references. During electroantennogram experiments, 3‐methyl‐1‐butanol, 3‐methylbutyl acetate, and ethyl hexanoate elicited high electrophysiological responses from Vespula vulgaris (L.) antennae. These compounds mediated attraction of V. vulgaris wasps in forest margins by trapping. A blend of these compounds could be used as a lure in a monitoring tool, or even a local suppression method if combined with a toxin.     

Ecological Restoration of Native Forest at Aratiatia, North Island, New Zealand

Successional pathways in native forest, planted 15–33 years ago on reconstructed surfaces to restore aesthetic values destroyed by hydro‐electric dam construction at Aratiatia, central North Island, New Zealand, were compared with those on similar surfaces left unplanted. Only native species were planted. Classification identified three canopy communities and several ground layer communities with significant inter‐stratum relationships: Pittosporum tenuifolium‐Sophora tetraptera short forest with ground layers dominated by litter; P. tenuifolium‐Kunzea ericoides short forest over adventive grasses on planted sites; and adventive Cytisus scoparius shrubland over grasses on unplanted sites. Planted communities mirror young secondary forests on intact substrates in the district, but have lower density and similar or higher basal area than such forests elsewhere. Established seedlings of seven planted canopy trees, mostly early successional bird‐dispersed species, are reasonably widespread in floristically rich Pittosporum‐Sophora forest. Seedlings of only two species are widespread in floristically poor Pittosporum‐Kunzea forest, and none on unplanted sites. This first large‐scale attempt at ecological restoration in New Zealand, by mass planting of new surfaces with early successional native woody species, has created aesthetically‐pleasing stands of indigenous forest on sites which would otherwise remain in relatively stable adventive shrubland communities for the foreseeable future. Only continued monitoring will show whether further management is necessary and whether natural processes are operating at a level sufficient to ensure that artificially initiated successions will continue along more or less natural pathways.     

Forest bolsters bird abundance,pest control and coffee yield

Efforts to maximise crop yields are fuelling agricultural intensification, exacerbating the biodiversity crisis. Low‐intensity agricultural practices, however, may not sacrifice yields if they support biodiversity‐driven ecosystem services. We quantified the value native predators provide to farmers by consuming coffee's most damaging insect pest, the coffee berry borer beetle (Hypothenemus hampei). Our experiments in Costa Rica showed birds reduced infestation by ~ 50%, bats played a marginal role, and farmland forest cover increased pest removal. We identified borer‐consuming bird species by assaying faeces for borer DNA and found higher borer‐predator abundances on more forested plantations. Our coarse estimate is that forest patches doubled pest control over 230 km² by providing habitat for ~ 55 000 borer‐consuming birds. These pest‐control services prevented US$75–US$310 ha‐year⁻¹ in damage, a benefit per plantation on par with the average annual income of a Costa Rican citizen. Retaining forest and accounting for pest control demonstrates a win–win for biodiversity and coffee farmers.     

The relationship between possum density and browse damage on kamahi in New Zealand forests

To minimize the impacts of introduced pests and to justify and prioritize pest control, managers need to know the relationship between pest density and damage. This relationship can be difficult to quantify because pest impacts can be highly variable. In New Zealand, introduced brushtail possums (Trichosurus vulpecula) browse a wide range of native forest species. However, possum browse is extremely patchy making it difficult to quantify the relationship between density and damage, meaning the benefits of reducing possum densities are poorly understood. We quantified patterns of possum browse on kamahi (Weinmannia racemosa), a common canopy tree species, at 21 forest sites that were repeat‐measured over an 8‐year period in the North Island, New Zealand, during which time possum densities fluctuated widely. We fitted a multilevel statistical model in order to quantify the relationship between possum density and browse damage while simultaneously quantifying how browse varied among trees, sites and years. Higher possum densities were associated with greater browse damage, but browse was also patchily distributed among trees at the same site, and among sites and years for a given possum density. This heterogeneity meant there was no simple density damage relationship, with the relationship differing from tree to tree and among sites and years. Our results show that at most sites reductions in possum density would have little benefit in reducing the probability of heavy browse on kamahi trees, but at a few sites there would be substantial benefits. This approach provides insights into the pattern and potential causes of variability in possum impacts, and a quantitative basis for prioritizing sites for possum control.     

Secondary forest succession differs through naturalised gorse and native kānuka near Wellington and Nelson

The dominant native woody species forming early-successional vegetation on formerly forested sites in lowland New Zealand were kānuka (Kunzea ericoides) and mānuka (Leptospermum scoparium) (Myrtaceae). These have been replaced extensively by gorse (Ulex europaeus, Fabaceae), a naturalised species in New Zealand. Because gorse typically gives way to native broadleaved (angiosperm) forest in about 30 years, it is often considered desirable for facilitating native forest restoration. We tested three hypotheses, derived from the New Zealand literature, on gorse and kānuka: (1) kānuka stands have a different species composition and greater species richness than gorse stands at comparable successional stages; (2) differences between gorse and kānuka stands do not lessen over time; and (3) several native plant taxa are absent from or less common in gorse than in kānuka stands. We sampled 48 scrub or low-forest sites in two regions, Wellington and Nelson. Sites were classified into one of four predefined categories – young gorse, young kānuka, old gorse, old kānuka – based on canopy height of the succession and the dominant early-successional woody species. Few characteristics of the sites and surrounding landscapes differed significantly among site categories, and none consistently across regions. The vegetation composition of gorse and kānuka and their immediate successors differed in both regions, mainly in native woody species. Species richness was often lower in gorse and there were fewer smallleaved shrubs and orchids in gorse. Persistent differences at the older sites suggest the successional trajectories will not converge in the immediate future; gorse leads to different forest from that developed through kānuka. Gorse-dominated succession is therefore not a direct substitute for native successions. We suggest areas of early native succession should be preserved, and initiated in landscapes where successions are dominated by gorse or other naturalised shrubs.     

Is Avian Malaria Playing a Role in Native Bird Declines in New Zealand? Testing Hypotheses along an Elevational Gradient

The mosquito-borne disease avian malaria (Plasmodium spp.) has impacted both captive populations and wild individuals of native New Zealand bird species. However, whether or not it is a cause of concern to their wild populations is still unclear. In Hawaii, the disease has been a major factor in the population declines of some native forest bird species, often limiting their elevational distribution due to an inverse relationship between force of infection and elevation. While studies have investigated latitudinal patterns of infection in New Zealand, elevational patterns are unexplored. To address this, a survey was conducted in Nelson Lakes National Park, a site experiencing native bird declines in which disease has been suggested as playing a role, to investigate whether there is a similar inverse relationship in New Zealand. Results from blood samples (n = 436) collected over three seasons across a broad elevational range (650–1400 m) support there being such a relationship. In addition, an overall higher prevalence in non-native (14.1%) versus native birds (1.7%) may indicate differential impacts on these two groups, while particularly high prevalence in non-native Turdus spp. supports previous suggestions that they are key reservoir hosts for the disease. Overall, these findings add weight to the hypothesis that avian malaria is playing a role in ongoing declines of native New Zealand birds.     

Breeding and survival of New Zealand Pigeons Hemiphaga novaeseelandiae

The breeding and survival of New Zealand Pigeons Hemiphaga novaeseelandiae were studied by radiotelemetry at three contrasting native forest sites in the North and South Islands of New Zealand. At each site, mean annual productivity was low (0-0.12 fledglings/adult) in relation to the mean annual rate of adult mortality (0.18-0.53). Losses of eggs and chicks to introduced mammals were the main identified causes of nest failure. Causes of adult mortality included episodic predation by introduced mammals and apparent starvation in spring at one site. At the most intensively-studied site (Pelorus Bridge), where 75 birds were radiotagged over 7 years, there was a marked annual variation in breeding success (0-0.3 fledglings/adult), including one season (1986–1987) when no breeding activity was detected at all. New Zealand Pigeons were legally hunted in the past, but our results indicate that harvesting is unlikely to be sustainable under current ecological conditions.     

Bone-seed (

Bone-seed, Chrysanthemoides monilifera ssp. monilifera (L.), is an environmental weed of coastal vegetation communities scattered throughout New Zealand. To assess the long-term implications for native forest regeneration in sites where bone-seed is present, we selected four study sites around Wellington, New Zealand, where bone-seed was abundant. We compared seed bank composition in bone-seed-invaded sites with nearby native forest patches, and monitored bone-seed and native seedling recruitment with and without control of mature bone-seed plants. We also tested the potential effects of fire on bone-seed recruitment in these communities by heating seeds prior to germination. Bone-seed, gorse (Ulex europaeus), and native species emerged from seed bank samples taken from bone-seed-invaded sites, but only native species and (less) gorse emerged from seed bank samples taken from native forest patches. Gorse germination was strongly promoted by heat but bone-seed germination was less affected by heat. Bone-seed seedling abundance increased dramatically following canopy removal, whereas native seedling abundance decreased dramatically. This suggests that disturbance of any form is likely to favour recruitment of bone-seed (and gorse) over native species, although in the long term, native seedlings can establish beneath the canopy of mature bone-seed plants. It is not yet known if, in the absence of further disturbance, regenerating native vegetation will eventually replace bone-seed in New Zealand.     

Mutualisms with the wreckage of an avifauna: the status of bird pollination and fruit dispersal in New Zealand

Worldwide declines in bird numbers have recently renewed interest in how well bird?plant mutualisms are functioning. In New Zealand, it has been argued that bird pollination was relatively unimportant and bird pollination failure was unlikely to threaten any New Zealand plants, whereas dispersal mutualisms were widespread and in some cases potentially at risk because of reliance on a single large frugivore, the kereru (Hemiphaga novaeseelandiae). Work since 1989, however, has changed that assessment. Smaller individual fruits of most plant species can be dispersed by mid-sized birds such as tui (Prosthemadera novaezelandiae) because both fruits and birds vary in size within a species. Only one species (Beilschmiedia tarairi) has no individual fruits small enough for this to occur. Germination of 19 fleshy-fruited species, including most species with fruits >8 mm diameter, does not depend on birds removing the fruit pulp. The few studies of fruit removal rates mostly (7 out of 10) show good dispersal quantity. So dispersal is less at risk than once thought. In contrast, there is now evidence for widespread pollen limitation in species with ornithophilous flowers. Tests on 10 of the 29 known native ornithophilous-flowered species found that in 8 cases seed production was reduced by at least one-third, and the pollen limitation indices overall were significantly higher than the global average. Birds also frequently visit flowers of many other smaller-flowered native species, and excluding birds significantly reduced seed set in the three species tested. So pollination is more at risk than once thought. Finally, analyses of both species numbers and total woody basal area show that dependence on bird pollination is unexpectedly high. Birds have been recorded visiting the flowers of 85 native species, representing 5% of the total seed-plant flora (compared with 12% of those with fleshy fruit) and 30% of the tree flora (compared with 59% with fleshy fruit). A higher percentage of New Zealand forest basal area has bird-visited flowers (37% of basal area nationally) than fleshy fruit (31%). Thus, bird pollination is more important in New Zealand than was realised, partly because birds visit many flowers that do not have classic ?ornithophilous? flower morphology.     

Effects of habitat transitions on rainforest bird communities across an anthropogenic landscape mosaic

We compared bird community responses to the habitat transitions of rainforest‐to‐pasture conversion, consequent habitat fragmentation, and post‐agricultural regeneration, across a landscape mosaic of about 600 km² in the eastern Australian subtropics. Birds were surveyed in seven habitats: continuous mature rainforest; two size classes of mature rainforest fragment (4–21 ha and 1–3 ha); regrowth forest patches dominated by a non‐native tree (2–20 ha, 30–50 years old); two types of isolated mature trees in pasture; and treeless pasture, with six sites per habitat. We compared the avifauna among habitats and among sites, at the levels of species, functional guilds, and community‐wide. Community‐wide species richness and abundance of birds in pasture sites were about one‐fifth and one‐third, respectively, of their values in mature rainforest (irrespective of patch size). Many measured attributes changed progressively across a gradient of increased habitat simplification. Rainforest specialists became less common and less diverse with decreased habitat patch size and vegetation maturity. However, even rainforest fragments of 1–3 ha supported about half of these species. Forest generalist species were largely insensitive to patch size and successional stage. Few species reached their greatest abundance in either small rainforest fragments or regrowth. All pastures were dominated by bird species whose typical native habitats were grassland, wetland, and open eucalypt forest, while pasture trees modestly enhanced local bird communities. Overall, even small scattered patches of mature and regrowth forest contributed substantial bird diversity to local landscapes. Therefore, maximizing the aggregate rainforest area is a useful regional conservation strategy.     

Diversity patterns of small mammals in the Zambales Mts., Luzon, Philippines

In 2004 and 2005, we conducted a survey of the small mammals on Mt. Tapulao (=Mt. High Peak, 2037 m) in the Zambales Mountains, Luzon Island, Philippines in order to obtain the first information on the mammals of this newly discovered center of endemism. We also tested two hypotheses regarding the relationship of species richness with elevation and the impact of alien species on native mammals. The survey covered five localities representing habitats from regenerating lowland rain forest at 860 m to mossy rain forest near the peak at 2024 m. We recorded 11 species, including 1 native shrew, 1 alien shrew, 8 native rodents, and 1 alien rodent. Two species of Apomys and one species of Rhynchomys are endemic to Zambales; this establishes the Zambales Mountains as a significant center of mammalian endemism. Species richness of native small mammals increased with elevation, from five species in the lowlands at 925 m to seven species in mossy forest at 2024 m; total relative abundance of native small mammals increased from 925 to 1690 m, then declined at 2024 m. Alien small mammals were restricted to highly disturbed areas. Our results support the prediction that maximum species richness of small mammals would occur in lower mossy forest near the peak, not near the center of the gradient. Our results also support the hypothesis that when a diverse community of native Philippine small mammals is present in either old-growth or disturbed forest habitat, “invasive” alien species are unable to penetrate and maintain significant populations in forest.     

The impact of environmental factors in birdsong acquisition using automated recorders

The use of automatic acoustic recorders is becoming a principal method to survey birds in their natural habitats, as it is relatively noninvasive while still being informative. As with any other sound, birdsong degrades in amplitude, frequency, and temporal structure as it propagates to the recorder through the environment. Knowing how different birdsongs attenuate under different conditions is useful to, for example, develop protocols for deploying acoustic recorders and improve automated detection methods, an essential part of the research field that is becoming known as ecoacoustics. This article presents playback and recapture (record) experiments carried out under different environmental conditions using twenty bird calls from eleven New Zealand bird species in a native forest and an open area, answering five research questions: (1) How does birdsong attenuation differ between forest and open space? (2) What is the relationship between transmission height and birdsong attenuation? (3) How does frequency of birdsong impact the degradation of sound with distance? (4) Is birdsong attenuation different during the night compared to the day? and (5) what is the impact of wind on attenuation? Bird calls are complex sounds; therefore, we have chosen to use them rather than simple tones to ensure that this complexity is not missed in the analysis. The results demonstrate that birdsong transmission was significantly better in the forest than in the open site. During the night, the attenuation was at a minimum in both experimental sites. Transmission height affected the propagation of the songs of many species, particularly the flightless ones. The effect of wind was severe in the open site and attenuated lower frequencies. The reverberations due to reflective surfaces masked higher frequencies (8 kHz) in the forest even at moderate distances. The findings presented here can be applied to develop protocols for passive acoustic monitoring. Even though the attenuation can be generalized to frequency bands, the structure of the birdsong is also important. Selecting a reasonable sampling frequency avoids unnecessary data accumulation because higher frequencies attenuate more in the forest. Even at moderate distances, recorders capture significantly attenuated birdsong, and hence, automated analysis methods for field recordings need to be able to detect and recognize faint birdsong.     

The species diversity of New Zealand forest birds: Some possible consequences of the modification of beech forests

The literature on forest birds in New Zealand is examined to see if the consequences of forest modification can be predicted. Forty‐four samples of birds, from North, South, and Stewart Islands, are classified according to four habitats of origin: virgin forest, modified forest, exotic forest, and suburban bush and gardens. An index of bird species diversity (BSD) is calculated for comparison, and where possible densities are tabulated.

Limited samples from modified forests in Westland suggest that the number of species is relatively smaller but the bird density is higher after modification. There do not seem to be any published quantitative data about birds in Westland exotic forests.

Data from the whole of New Zealand show that bird density increases as forest habitats change from virgin, to modified, to exotic, to suburban bush and gardens. BSD and equitability do not differ among these habitats. The number of species of native birds and their diversity decline as the habitat is more extensively altered, but their total density tends to remain constant. More productive forest habitats have the same BSD as other habitats. Diversity seems to be limited by the small variety of bird species available, and the more productive habitats could probably support more species. All habitats had a much higher diversity of birds before colonisation by the European.     

Climbing asparagus,Asparagus scandens Thunb.: a South African in your forest patch

Climbing asparagus, Asparagus scandens Thunb., currently has a patchy distribution in New Zealand, mainly in disturbed lowland forest remnants near towns and the coast, predominantly in the North Island but found as far south as Banks Peninsula. Here it prevents regeneration of native seedlings and smothers or strangles understorey shrubs and saplings. Based on its current distribution, it tolerates open sunny sites to deep shade and damp or dry forest. Left unchecked and aided by birds and humans, climbing asparagus is likely to spread considerably in the next decade, consolidating its current distribution in New Zealand. Several characteristics of the species make it difficult to control: the small, fine seedlings are hard to find, adult plants entwine with native plants, much of the plant’s biomass is underground and the apical meristem will resprout if left in the ground after control.