Zealand Falcon Research Articles

Designing Timber Harvesting to Enhance New Zealand Falcon Populations

ABSTRACTPrevious breeding‐season studies of threatened New Zealand falcons (Falco novaeseelandiae) in plantation forests have suggested that falcons benefit when harvesting creates a mosaic of differently aged stands, especially where young and mature tree stands are adjacent. Thus, changes in the rate and pattern of harvesting may affect habitat heterogeneity by altering the size and distribution of forest patches. We sought to determine guidelines for harvesting that would most benefit falcons by increasing the carrying capacity of the forest for falcons. We used radio‐tracking to determine the home‐range sizes of non‐breeding falcons over 3 seasons and compared winter home‐range overlap in the most‐selected land cover types by falcons (mature‐young edges and open patches) with other land cover types. The distribution of open patches and edges between mature stands and recently cleared areas affected falcon home ranges, home‐range overlap, and the likelihood of nesting. Specifically, home ranges were smaller as the density of edges and percentage of open patch increased, and there was greater home‐range overlap between individuals in the most‐selected land cover types. Numbers of falcons decreased as the size of open patches increased, concomitant with a decrease in edge size, the number of edge borders, and the number of open patches. The likelihood of nesting also decreased as open patch size increased. Our results indicate that smaller open patches spread through a forest, maximizing the amount of mature‐young edges, will favor smaller home ranges and therefore potentially greater numbers of falcons. We recommend harvesting protocols that ensure that open patches (0–3‐yr‐old stands) are <4 km2 in size and retain at least small stands of mature pine to maintain a high density of edges. Similar protocols may increase the carrying capacity for other species occurring in managed systems involving fragmented landscapes or small reserves. © 2021 The Wildlife Society.

Annual survival estimates and risk of fluoroacetate (1080) secondary poisoning for New Zealand falcons (Falco novaeseelandiae) in a managed exotic forest

Context The risk of secondary poisoning to native fauna during pest control operations is an issue of global concern. In New Zealand, non-target impacts during sodium fluoroacetate (1080) operations are particularly contentious. 1080 is used extensively for pest control for conservation, bovine tuberculosis control, and in plantation forestry for seedling protection from herbivores. The endemic New Zealand falcon (Falco novaeseelandiae) breeds in Kaingaroa forest, an intensively managed pine plantation where regular 1080 poison operations are conducted; however, causes of mortality and risks of secondary poisoning by 1080 are not well documented. Aims We aimed to investigate mortality and survival of adult falcons with an emphasis on assessing the possible role of 1080 poisoning in annual mortality. Methods Using radio-telemetry and visual observations, we monitored 37 marked adult falcons before and after 1080 operations in 2013–14 (16 through carrot-bait and 21 through cereal-bait operations) and assessed mortality causes through post-mortem examinations. Using Program MARK, the annual survival rates for adults and independent juveniles were estimated from long-term banding data (2003–2014). Key results Survival of falcons was high through both cereal-bait (21/21) and carrot-bait (15/16) 1080 operations (overall 95% CI for survival = 84–100%). The exception was a radio-tagged male that died of unknown causes within a fortnight of an operation and tested negative for 1080 residues. Three falcons were depredated by introduced mammals. One falcon was found dead in an emaciated condition but evidently died from head injury through Australasian magpie (Cracticus tibicen) attack. The annual survival rate of falcons estimated from long-term banding was 80 ± 6.0% (mean ± s.e.) for adults and 29 ± 0.1% for juveniles. Conclusions No adult falcon death was attributable to 1080 poisoning in this study. Identifiable mortalities were attributable to depredation by introduced mammals and an injury from an Australasian magpie. The annual survival rate of Kaingaroa falcons was comparable to those of other raptor species worldwide. Implications The risk to adult falcons from 1080 secondary poisoning is likely low. Whether this is also true for juveniles requires further study.

New Zealand falcon prey selection may not be driven by preference based on prey nutritional content

New Zealand falcon prey selection may not be driven by preference based on prey nutritional content

A retrospective survey into the presence of Plasmodium spp. and Toxoplasma gondii in archived tissue samples from New Zealand raptors: New Zealand falcons (Falco novaeseelandiae), Australasian harriers (Circus approximans) and moreporks (Ninox novaeseelandiae).

Human colonisation of New Zealand has resulted in the introduction of emerging diseases, such as avian malaria and toxoplasmosis, which arrived with their exotic avian and mammalian hosts. Plasmodium spp. and Toxoplasma gondii have a wide host range, and several species of endemic New Zealand birds have developed a fatal disease following infection with either pathogen. However, no reports of either toxoplasmosis or avian malaria in New Zealand raptors, namely, the New Zealand falcons (Falco novaeseelandiae), Australasian harriers (Circus approximans) and moreporks (Ninox novaeseelandiae) exist in the literature. Therefore, this study was designed to determine if these two pathogens are present in these raptors through a retrospective analysis of archived tissue samples. Detection and isolate identification of these pathogens was determined using established histological and molecular techniques. All three species of New Zealand raptors tested positive for the presence of Plasmodium spp. (10/117; 8.5%) and an atypical genotype of T. gondii (9/117; 7.7%). Plasmodium lineages identified include P. elongatum GRW6, P. relictum SGS1, P. relictum PADOM02 and Plasmodium sp. LINN1. Two Australasian harriers and one morepork tested positive for the presence of both Plasmodium spp. and T. gondii. However, the pathogenicity of these organisms to the raptors is unclear as none of the tissues showed histological evidence of clinical disease associated with Plasmodium spp. and T. gondii infections. Thus, these results demonstrate for the first time that these two potential pathogens are present in New Zealand's raptors; however, further research is required to determine the prevalence and pathogenicity of these organisms among the living populations of these birds in the country.

Winter habitat use of New Zealand falcon (Falco novaeseelandiae ferox) in an intensively managed pine plantation, central North Island, New Zealand

Winter habitat use of New Zealand falcon (Falco novaeseelandiae ferox) in an intensively managed pine plantation, central North Island, New Zealand

Spatial distribution of late Holocene bird bones in the Mason Bay dune system, Stewart Island, New Zealand

ABSTRACTMany of New Zealand’s coastal sand dune systems contain naturally accumulated deposits of late Holocene bones, providing an important archive of our pre-settlement faunas. However, the accumulation and taphonomic processes that operate in natural dune deposits are poorly understood. Here, I contribute to our understanding of these processes through analysing spatial patterns of bone distribution in an extensive late Holocene dune system at Mason Bay, Stewart Island. The bone assemblage was collected between December 2002 and February 2003, and included 2880 identified bones from at least 28 bird species. These included extinct species (South Island piopio, Turnagra capensis), regionally rare species (e.g. weka, Gallirallus australis and New Zealand falcon, Falco novaeseelandiae) and locally rare species (e.g. South Island kākā, Nestor meridionalis meridionalis). Significant effects of distance to beach, and distance to the edge of woody vegetation, were found for bones of certain bird groups. The results indicate three main sources of bird bones for the Mason Bay dune system assemblage: 1. nesting colonies within the dunes; 2. storm-wrecked seabirds; and 3. birds inhabiting woody vegetation bordering the dunes. Understanding source biases for dune bone deposits will allow more informed interpretations about the composition of the local prehistoric faunal communities.

Home Range and Habitat Use of New Zealand Falcons (Falco novaeseelandiae) in an Exotic Plantation Forest During the Breeding Season

The New Zealand Falcon (Falco novaeseelandiae) is a threatened endemic species whose numbers have been reduced by habitat loss and the introduction of exotic predators. The species has recently been discovered breeding in exotic plantation forests. Understanding how New Zealand Falcons use plantation forests is critical to its effective management in this habitat. To determine patterns of habitat selection and inform habitat management, we studied the home-range size and habitat use of 13 adult New Zealand Falcons in Kaingaroa pine plantation. This plantation comprises 180,000 ha of nonnative pine trees that are planted and harvested in discrete ‘stands’ that create a mosaic of pine stand ages across the landscape. We radio-tracked eight males and five females for 12 wk during the 2004 and 2005 breeding seasons. Mean home-range sizes were 9.2 ± 4.2 km2 for males and 6.2 ± 3.2 km2 for females (mean ± SD). To investigate habitat use, pine stands were categorized by tree age and further classified into stand edge and stand interior. Both sexes strongly favored the edges between pine stands where stands less than 4 yr old bordered those greater than 19 yr old. Females also preferentially used the interior of pine stands less than 4 yr old, whereas males were more often found along the edges of these young stands. We conclude that if forestry managers wish to enhance the suitability of their estates for the New Zealand Falcon, they should provide a mosaic of different aged stands, while ensuring that stands less than 4 yr old bordering stands greater than 19 yr old are consistently available.Falco novaeseelandiae es una especie endémica amenazada cuyos números poblacionales se han visto reducidos por la pérdida de hábitat y la introducción de depredadores exóticos. Recientemente se ha descubierto a la especie reproduciéndose en plantaciones forestales exóticas. Entender cómo F. novaeseelandiae utiliza los bosques implantados es crítico para su manejo efectivo en este tipo de hábitat. Para determinar los patrones de selección de hábitat y conducir el manejo de hábitat, estudiamos el tamaño del rango de hogar y el uso de hábitat de 13 individuos adultos de F. novaeseelandiae en la plantación de pinos de Kaingaroa. Esta plantación comprende 180,000 ha de pinos exóticos implantados y que son explotados en rodales discretos que crean un mosaico de rodales de pinos de distinta edad a través del paisaje. Localizamos con radio transmisores ocho machos y cinco hembras durante 12 semanas en las épocas reproductivas de 2004 y 2005. Los tamaños medios de rango de hogar fueron de 9.2 ± 4.2 km2 para los machos y de 6.2 ± 3.2 km2 para las hembras (media ± DE). Para investigar el uso de hábitat, los rodales de pino fueron categorizados por edad de árbol y clasificados en borde de rodal e interior de rodal. Ambos sexos mostraron una marcada preferencia por los bordes entre rodales de pino, donde los rodales de menos de cuatro años de edad bordearon aquellos de más de 19 años de edad. Las hembras también utilizaron preferentemente el interior de los rodales de pino de menos de cuatro años de edad, mientras que los machos fueron encontrados más a menudo a lo largo de los bordes de estos rodales jóvenes. Concluimos que si los encargados de la forestación desean mejorar la aptitud de sus plantaciones para F. novaeseelandiae, deberían mantener un mosaico de rodales de edades diferentes, asegurando que los rodales de menos de cuatro años de edad estén bordeando los rodales de más de 19 años de edad.

New Zealand Falcon nests suffer lower predation in agricultural habitat than in natural habitat

SummaryIntroduced mammalian predators have been implicated in the majority of avian extinctions on oceanic islands around the globe. Nowhere is this more apparent than in the decimated New Zealand avifauna, where introduced predators remain the primary threat to virtually all surviving endemic species, including the threatened New Zealand Falcon Falco novaeseelandiae. We used remote videography at falcon nests and conducted an artificial nest experiment to compare the rates of predation and responsible predators of falcons nesting in hills against those nesting in nearby commercial vineyards. Overall, 63% of artificial nests in the hills were predated, compared with 38% in vineyards. Further, artificial eggs were predated faster in the hills than those placed in vineyards. Video footage revealed that the suite of predators visiting real falcon nests was similar to those identified attacking artificial nests. However, predators differed across habitats, with nests in vineyards being predated mainly by hedgehogs Erinaceus europaeus and Australasian Harriers Circus approximans, whereas nests in the hill environments were mainly attacked by stoats Mustela erminea. These results demonstrate the important implications of habitat type on predation pressure associated with introduced predators. These may well prove a fruitful avenue of management if breeding can be fostered in safer areas, as in the case of this threatened falcon.

The New Zealand falcon and wind farms: a risk assessment framework

Internationally, birds of prey are often reported as being relatively prone to collision with wind turbines in comparison to other groups of birds. However, as yet it is unclear to what extent New Zealand's only endemic bird of prey, the New Zealand falcon (Falco novaeseelandiae), is at risk. In this paper we summarise the potential for wind farms to impact New Zealand falcon, evaluate the efficacy of a range of risk assessment and post-consent monitoring practices, and present options for mitigating and/or offsetting any residual effects. We conclude that the lack of knowledge on the effects of wind farms on New Zealand falcon is the result of inconsistency in the assessment methods thus far employed and the absence of a coordinated approach to monitoring methods and the dissemination of results. To remedy this we present a risk assessment framework that, if adopted, will provide the information necessary to ensure alternative energy targets can be met without compromising the conservation of this threatened species.

Factors influencing the behavioural development of juvenile New Zealand Falcons (Falco novaeseelandiae)

Adult raptors are thought to train their progeny in flight and hunting techniques during the period of dependence after fledging. Parental teaching is poorly understood but its effects may impinge on the success of reintroduction projects where juveniles are released into areas without adults, as is commonly done with raptors. We compared behavioural development over the first 4 weeks after fledging in wild-reared juvenile New Zealand Falcons (Falco novaeseelandiae) with that of juvenile Falcons recently hack-released as part of a conservation initiative. Juveniles with parents spent nearly half as much time perching, spent twice as much time playing, and chased conspecifics five-times more often than juveniles without parents. Juveniles with siblings chased conspecifics 60 times more often, and engaged in twice as much play behaviour compared with juveniles without siblings. We suggest that, provided juvenile New Zealand Falcons are hack-released in groups, reintroduction of this threatened species without adults does not have a major effect on the behavioural development of individuals, although ongoing monitoring to corroborate these results with a larger sample size is recommended.

Post-construction avian mortality monitoring at Project West Wind

Post-construction avifauna investigations were undertaken at Project West Wind, Meridian Energy Limited's 62-turbine wind farm on the Wellington south coast. These investigations were required in accordance with the resource consent conditions to quantify the level of avian mortalities occurring at the wind farm, particularly in regard to New Zealand falcon (Falco novaeseelandiae), kākā (Nestor meridionalis) and kererū (Hemiphaga novaeseelandiae). This is the first comprehensive study at a New Zealand operating wind farm. The methods included three field components necessary to calculate annual estimates of mortalities across the wind farm site: routine turbine searches; carcass detection trials; and carcass removal trials. Results from years 1 and 2 of a three-year programme are presented. To date, mortalities have been recorded for 17 taxa at 18 of the 24 study turbines. There have been no recorded mortalities of falcon, kākā or kererū. Australasian harrier (Circus approximans) has been the species for which the most mortalities have been recorded. Overall estimated annual mortality rates for years 1 and 2 were calculated to be approximately six and five birds per turbine respectively.

Translocation of Threatened New Zealand Falcons to Vineyards Increases Nest Attendance, Brooding and Feeding Rates

Anthropogenic landscapes can be rich in resources, and may in some cases provide potential habitat for species whose natural habitat has declined. We used remote videography to assess whether reintroducing individuals of the threatened New Zealand falcon Falco novaeseelandiae into a highly modified agricultural habitat affected the feeding rates of breeding falcons or related breeding behavior such as nest attendance and brooding rates. Over 2,800 recording hours of footage were used to compare the behavior of falcons living in six natural nests (in unmanaged, hilly terrain between 4 km and 20 km from the nearest vineyard), with that of four breeding falcon pairs that had been transported into vineyards and nested within 500 m of the nearest vineyard. Falcons in vineyard nests had higher feeding rates, higher nest attendance, and higher brooding rates. As chick age increased, parents in vineyard nests fed chicks a greater amount of total prey and larger prey items on average than did parents in hill nests. Parents with larger broods brought in larger prey items and a greater total sum of prey biomass. Nevertheless, chicks in nests containing siblings received less daily biomass per individual than single chicks. Some of these results can be attributed to the supplementary feeding of falcons in vineyards. However, even after removing supplementary food from our analysis, falcons in vineyards still fed larger prey items to chicks than did parents in hill nests, suggesting that the anthropogenic habitat may be a viable source of quality food. Although agricultural regions globally are rarely associated with raptor conservation, these results suggest that translocating New Zealand falcons into vineyards has potential for the conservation of this species.

Effects of Introducing Threatened Falcons into Vineyards on Abundance of Passeriformes and Bird Damage to Grapes

Agricultural landscapes are becoming an important focus of animal conservation, although initiatives to conserve predators to date have rarely provided economic benefits to agricultural producers. We examined whether introduction to vineyards of the New Zealand Falcon (Falco novaeseelandiae), a species listed as threatened by the New Zealand Department of Conservation, affected the abundance of 4 species of Passeriformes that are considered vineyard pests or affected the amount of economic loss due to grape (Vitis vinifera) damage. Three of the species were introduced and remove whole grapes from bunches (Blackbird [Turdus merula], Song Thrush [Turdus philomelos], and Starling [Sturnus vulgaris]), whereas the one native species (Silvereye [Zosterops lateralis]) pecks holes in grapes. The introduction of falcons to vineyards was associated with a significant decrease in the abundance of introduced passerines and with a 95% reduction in the number of grapes removed relative to vineyards without falcons. Falcon presence was not associated with a change in the number of Silvereyes, but there was a 55% reduction in the number of grapes pecked in vineyards with falcons. Our results indicate that, relative to damage in vineyards without falcons, the presence of a falcon could potentially result in savings of US$234/ha for the Sauvignon Blanc variety of grapes and $326/ha for Pinot Noir variety of grapes.

Nest-site selection of New Zealand Falcons (Falco novaeseelandiae) in plantation forests and the implications of this to forestry management

This study investigates the factors that determine nest-site selection by New Zealand Falcons (Falco novaeseelandiae) in a plantation pine forest. Selection was examined by measuring habitat and forestry management variables at actual nesting sites and randomly selected sites in the forest. Nesting sites were located on the ground in pine stands up to 5 years old, with unplanted and 1-year-old stands of pine selected preferentially for nesting. Overall, 54% of pairs nested in the same stand of pines in a subsequent year, whereas 44% moved to a stand of the same age or younger and 2% moved to older stands. Falcons chose nesting sites close to older pine trees and with cover over the scrape. New Zealand Falcons benefit from clear-fell harvesting that creates a mosaic of stand ages across a plantation. This mosaic provides both suitable nesting sites and an abundance of prey. This threatened species benefits from felling plantation forests in fairly small, discrete stands.

A portable low‐cost remote videography system for monitoring wildlife

Summary1. Remote videography allows continuous and reviewable recording of unique behaviours with minimal disturbance to focus individuals. It is therefore an excellent, although often unaffordable, method for observing the behaviour of wildlife in the field.2. We describe a digital video‐based remote videography design that costs under USD 900 and requires relatively minimal maintenance. The system is portable and can record continuously or when motion is detected.3. Using the threatened New Zealand falcon as a model, in a single season of camera deployment we were able to record a number of unique events, including a new prey species for the falcon and the complete depredation of one nest.4. Only 16% of potential recording hours were lost, the majority of which were as a result of battery failure (52% of failures) or the camera becoming dislodged (33% of failures).5. This system will be useful for researchers in all fields who require a reliable, cost‐effective means of recording wildlife behaviour in remote locations.

Home Range and Habitat Use of the New Zealand Falcon (Falco novaeseelandiae) within a Plantation Forest: A Satellite Tracking Study

We tracked two adult and three juvenile New Zealand falcons (Falco novaeseelandiae) in Kaingaroa Forest pine plantation from 2002 to 2008 using Argos satellite technology. The home ranges for both adults and juveniles varied, ranging between 44 and 587 km2. The falcons occasionally utilised areas outside the forest and used stands of all ages within the forest, generally in proportion to their availability. For the most part, the juveniles remained within ca. 8 km of their nests and dispersed at 58, 69, and 68 days after fledging. Falcon movement information was obtained from an average of four location points per tracking day per falcon at a putative accuracy of 350 m. The transmitters, including their solar charge capability, performed well in the forest environment. The use of all stand ages highlights the importance of forestry practises that maintain a mosaic of different aged pine stands.

Breeding Season Diet and Prey Selection of the New Zealand Falcon (Falco novaeseelandiae) in a Plantation Forest

We studied the diet of the endemic New Zealand Falcon (Falco novaeseelandiae) in a pine plantation forest by identifying species occurring in pellets and prey remains collected from 37 nest sites during the 2003 and 2004 breeding seasons. We assessed bird species abundance along transects in different-aged pine stands and along stand edges. Diet and prey abundance were compared to determine whether birds were taken disproportionately or in proportion to their abundance in the environment. Birds composed the greatest proportion of the diet, 84% by frequency and 74% by biomass. Common Chaffinches (Fringilla coelebs) were taken most frequently, but Eurasian Blackbirds (Turdus merula) and European rabbits (Oryctolagus cuniculus) contributed more by biomass, although rabbits were not recorded at every nest site. Bird density increased significantly with stand age but was highest along stand edges. Chaffinches were the most abundant species and taken in proportion to their availability. Species that occurred in open habitat (e.g., Yellowhammers [Emberiza citrinella]) or were of medium size (e.g., blackbirds) were taken more than expected based on their availability. Very small species (e.g., Grey Gerygone [Gerygone igata]) were taken in lower proportions than expected from their abundance. Proportions of bird species preyed upon were correlated most closely with bird species abundance in young pine stands (P = 0.02, r2 = 0.52). In a pine plantation habitat, New Zealand Falcons took primarily the more abundant species, those intermediate in size (16–160 g), and those frequenting open habitat.

Serratospiculosis in a New Zealand Falcon (Falco novaeseelandiae)

CASE HISTORY: An adult New Zealand falcon was presented with metacarpal fractures in the left wing. CLINICAL FINDINGS: In addition to the fractures, radiographs revealed an area of opacity in the air sacs. A few days after hospitalisation and initiation of treatment of the fractures, the bird developed signs of respiratory disease; the area of opacity was found to have increased in size and density. Treatment with antibiotics and nebulisation was commenced; the bird initially responded but respiratory signs subsequently worsened and the bird died. At necropsy, air sacculitis and bronchopneumonia were associated with numerous nematodes in the air sacs, which were morphologically consistent with Serratospiculum guttatum. DIAGNOSIS: Serratospiculosis CLINICAL RELEVANCE: The discovery of this parasite and the associated disease for the first time in New Zealand indicates that it should be considered in the differential diagnosis of respiratory disease in falcons and possibly other raptors in New Zealand.

Predicting the distribution of raptors using remote sensing techniques and Geographic Information Systems: A case study with the Eastern New Zealand falcon (Falco novaeseelandiae)

Remote sensing and Geographic Information System techniques were used to predict the distribution of nest site habitats of Eastern New Zealand falcons (Falco novaeseelandiae) in Otago. Satellite imagery (SPOT 4) was used to produce a vegetation map, which was integrated into a GIS database with contour, stream, road, and house data extracted from digital topographical maps. Habitat selection criteria were analysed comparing habitat features in the vicinity of nest sites with those available within the study area. Habitat selection criteria, including vegetation type, aspect, elevation, slope, terrain steepness, distance to water and human influence, were combined to build a model predicting the potential distribution of falcon nests. Our evaluation of the model showed that Eastern New Zealand falcons do select nesting territories in areas predicted by the model to be suitable breeding habitat. This technique has the potential to facilitate the location of falcon breeding sites, to allow more accurate estimates of the distribution, extent, and status of nesting habitat of New Zealand falcons, and could help to estimate the total population size and thereby enable more rigorous evaluation of the threat status of the species.

A late Pleistocene predator-accumulated avifauna from Kids Cave, West Coast, South Island, New Zealand

A fossil deposit excavated from the floor of Kids Cave, West Coast, South Island, New Zealand, is interpreted as having been primarily accumulated by New Zealand falcon Falco novaeseelandiae, with some contribution by Haast's eagle Harpagornis moorei. The fauna is rich: 3699 bones represented 41 bird species, two frog species, unspecified geckoes and skinks, and one bat species. Fossil deposition was mainly within the Last Glacial Maximum from about 22,000 cal yr bp to about 15,000 cal yr bp, with a marked change in sediment characteristics at the onset of the LGM's coldest period. Chronological control is given by three Uranium-series dates for a speleothem and radiocarbon AMS dating of four avian eggshell samples and one bone. The fauna is the first extensive predator accumulation of LGM age described from the West Coast of the South Island, and it indicates a palaeoenvironment of a mosaic of shrublands with forest patches. The onset of the coldest part of the LGM (Aurora 3 glacial advance, 19,500—19,000 cal yrs bp) saw marked climate cooling/drying affecting the site, but the avifauna indicates that although open-country taxa became more common in this period, some forest persisted nearby throughout the remainder of the LGM.