Vocal cooperation between the sexes in Little Spotted Kiwi Apteryx owenii

Sexual call dimorphism in birds is usually associated with sexual size dimorphism. Departures from this relationship can be used to infer call function, but research into inter‐sexual call differences, as with song function in general, has been restricted by a bias towards male passerines. The nocturnal and flightless New Zealand kiwi (Apterygidae) are acoustically similar but taxonomically and ecologically very different from other birds, so provide a contrast in exploring avian call function and evolution. However, kiwi acoustic ecology is poorly understood, with the calls of only one of the five kiwi species spectrally described, and acoustic differences between the sexes virtually unknown. We conducted the first bioacoustic study of Little Spotted Kiwi Apteryx owenii, and assessed sexual call dimorphism in this species. There were significant inter‐sexual differences in call temporal and frequency characteristics that were not related to size dimorphism. Contribution to duets and variation in temporal structure with call context also differed between the sexes. We suggest that these differences indicate divergent call function, with male calls more suited for territory defence, and female calls for pair contact. There was a striking lack of overlap in the frequency spectrum distributions of male and female calls, which was also unrelated to size and was further emphasized by the presence of formants in female calls. We propose that this provides evidence for inter‐sexual acoustic cooperation in call frequency, of a type which to our knowledge has not previously been described in birds. This may result from selection for enhanced joint resource defence in kiwi.     

Role of predation in the decline of kiwi,

Kiwi have declined markedly in abundance and range since human settlement of New Zealand. Three of the four species are still extant in mainland forests, despite decades of co-existence with various introduced mammals. Little spotted kiwi is now probably confined to offshore islands. The role of introduced mammals in these population declines was evaluated by measuring the survival rates of adults, eggs and chicks of brown kiwi (A. mantelli) and great spotted kiwi (A. haastii) in mainland forests. Mortality rates of adults ranged from 5%-16% and did not differ significantly between species or sexes. Overall, 14 out of 209 adult kiwi died during 159.6 radio-tracking years. Predators definitely caused five of these deaths. Sixty-nine (68%) of 102 eggs from 77 nesting attempts by 48 pairs failed to hatch. Predators probably caused about 10% of egg failures. Only three of 49 chicks probably survived to adulthood, indicating a juvenile mortality rate of about 94%. Predators killed at least 8% of chicks, 45% of juveniles, and possibly as many as 60% of all young kiwi. Ferrets and dogs were the main predators of adult kiwi, possums and mustelids were the main egg predators, while stoats and cats were largely responsible for the deaths of young kiwi. Population models show that northern brown kiwi are currently declining at 5.8% per annum. This decline could be halted by cutting the current predation rates on young kiwi by about 34% to 33%.     

The Anatomy of the bill Tip of Kiwi and Associated Somatosensory Regions of the Brain: Comparisons with Shorebirds

Three families of probe-foraging birds, Scolopacidae (sandpipers and snipes), Apterygidae (kiwi), and Threskiornithidae (ibises, including spoonbills) have independently evolved long, narrow bills containing clusters of vibration-sensitive mechanoreceptors (Herbst corpuscles) within pits in the bill-tip. These ‘bill-tip organs’ allow birds to detect buried or submerged prey via substrate-borne vibrations and/or interstitial pressure gradients. Shorebirds, kiwi and ibises are only distantly related, with the phylogenetic divide between kiwi and the other two taxa being particularly deep. We compared the bill-tip structure and associated somatosensory regions in the brains of kiwi and shorebirds to understand the degree of convergence of these systems between the two taxa. For comparison, we also included data from other taxa including waterfowl (Anatidae) and parrots (Psittaculidae and Cacatuidae), non-apterygid ratites, and other probe-foraging and non probe-foraging birds including non-scolopacid shorebirds (Charadriidae, Haematopodidae, Recurvirostridae and Sternidae). We show that the bill-tip organ structure was broadly similar between the Apterygidae and Scolopacidae, however some inter-specific variation was found in the number, shape and orientation of sensory pits between the two groups. Kiwi, scolopacid shorebirds, waterfowl and parrots all shared hypertrophy or near-hypertrophy of the principal sensory trigeminal nucleus. Hypertrophy of the nucleus basorostralis, however, occurred only in waterfowl, kiwi, three of the scolopacid species examined and a species of oystercatcher (Charadriiformes: Haematopodidae). Hypertrophy of the principal sensory trigeminal nucleus in kiwi, Scolopacidae, and other tactile specialists appears to have co-evolved alongside bill-tip specializations, whereas hypertrophy of nucleus basorostralis may be influenced to a greater extent by other sensory inputs. We suggest that similarities between kiwi and scolopacid bill-tip organs and associated somatosensory brain regions are likely a result of similar ecological selective pressures, with inter-specific variations reflecting finer-scale niche differentiation.     

Survival of brown kiwi (

Brown kiwi (Apteryx mantelli) in central Northland have been monitored for up to 32 months of sustained exposure to brodifacoum poison. The cereal baits were placed in bait stations to target brushtail possums (Trichosurus vulpecula). Annual survival of 55 radio-tagged adult kiwi in two poisoned forest patches has been high (95.9%), and similar to that in two nearby unpoisoned forest patches and in the patches before poison was used (95.3%). The two adult birds tested of the four that died in the poisoned areas had no traces of brodifacoum at the detection limit of 0.05 mg kg(-1). With an improved detection limit of 0.02 mg kg(-1), no traces of brodifacoum were found in nine eggs collected over 18 months after adults were first exposed to the poison. Of four chicks tested (detection limit: 0.005 to 0.02 mg kg(-1)), that had apparently died of natural causes or were killed by predators, three contained traces of brodifacoum (0.01—0.18 mg kg(-1)). The median survival of 39 radio-tagged chicks in the poisoned areas (36 days) was significantly better than that of 18 chicks in untreated areas nearby (15 days). Kiwi chicks may be more vulnerable than adult kiwi to accidental poisoning because of physiological or behavioural differences; however, the effects of sustained exposure to low levels of brodifacoum poison may not be visible in the adult population for several years. At this stage of the ongoing study, the benefits to kiwi of this method of pest control outweigh the costs, because chick survival is greatly improved.     

Evidence for an auditory fovea in the New Zealand kiwi (Apteryx mantelli)

Kiwi are rare and strictly protected birds of iconic status in New Zealand. Yet, perhaps due to their unusual, nocturnal lifestyle, surprisingly little is known about their behaviour or physiology. In the present study, we exploited known correlations between morphology and physiology in the avian inner ear and brainstem to predict the frequency range of best hearing in the North Island brown kiwi. The mechanosensitive hair bundles of the sensory hair cells in the basilar papilla showed the typical change from tall bundles with few stereovilli to short bundles with many stereovilli along the apical-to-basal tonotopic axis. In contrast to most birds, however, the change was considerably less in the basal half of the epithelium. Dendritic lengths in the brainstem nucleus laminaris also showed the typical change along the tonotopic axis. However, as in the basilar papilla, the change was much less pronounced in the presumed high-frequency regions. Together, these morphological data suggest a fovea-like overrepresentation of a narrow high-frequency band in kiwi. Based on known correlations of hair-cell microanatomy and physiological responses in other birds, a specific prediction for the frequency representation along the basilar papilla of the kiwi was derived. The predicted overrepresentation of approximately 4-6 kHz matches potentially salient frequency bands of kiwi vocalisations and may thus be an adaptation to a nocturnal lifestyle in which auditory communication plays a dominant role.     

The eggshell structure in apteryx; form,function, and adaptation

Apteryx is a genus of flightless birds endemic to New Zealand known to lay very large eggs in proportion to body weight. The eggshell of Apteryx is unusually thin and less porous than allometrically expected possibly as a compensation for a very long incubation period. Past studies have been carried out on Apteryx australis, a species which once comprised all kiwi with brown plumage, now separated into three distinct species. These species use different habitats and live at different latitudes and altitudes, therefore generating a need to revise our knowledge of the attributes of their eggshells. In this study, we measured the physical characteristics and water conductance on eggshell fragments of these three species and Great‐spotted Kiwi and relate them to the environmental conditions of their respective environments; we also measured the water vapor conductance of Brown Kiwi eggs of late stages of incubation. We found that several trade‐offs exist between incubation behavior, environmental conditions, and eggshell structure. We found differences between species in eggshell water vapor conductance seemingly related to altitude; Brown Kiwi and Rowi generally inhabiting lower altitudes had the highest conductance and Tokoeka, generally living in montane environments, the lowest. This is achieved by an increased eggshell thickness rather than a pore area reduction. Finally, the water vapor conductance late in incubation was 58% higher than infertile unincubated eggs, suggesting a drastic increase in conductance throughout the long incubation period. Using the values previously reported, we calculated the embryonic eggshell thinning to be 32.5% at the equatorial region of the eggshell. We describe several new features, such as triangular mineral particles in the cuticle, reported for the extinct Trigonoolithus amoei, and confirmed the existence of plugged pores. We suggest that these structures provide microbial protection needed by a burrow nesting species with a long incubation period.     

Characterisation of class II B MHC genes from a ratite bird,the little spotted kiwi (<Emphasis Type="Italic">Apteryx owenii</Emphasis>)

Major histocompatibility complex (MHC) genes are important for vertebrate immune response and typically display high levels of diversity due to balancing selection from exposure to diverse pathogens. An understanding of the structure of the MHC region and diversity among functional MHC genes is critical to understanding the evolution of the MHC and species resilience to disease exposure. In this study, we characterise the structure and diversity of class II MHC genes in little spotted kiwi Apteryx owenii, a ratite bird representing the basal avian lineage (paleognaths). Results indicate that little spotted kiwi have a more complex MHC structure than that of other non-passerine birds, with at least five class II MHC genes, three of which are expressed and likely to be functional. Levels of MHC variation among little spotted kiwi are extremely low, with 13 birds assayed having nearly identical MHC genotypes (only two genotypes containing four alleles, three of which are fixed). These results suggest that recent genetic drift due to a species-wide bottleneck of at most seven birds has overwhelmed past selection for high MHC diversity in little spotted kiwi, potentially leaving the species highly susceptible to disease.     

The breeding season of three species of kiwi (Apteryx) in captivity as determined from egg-laying dates

Records from kiwi ( Apteryx spp.) breeding centres were used to obtain laying dates of 403 North Island brown kiwi ( Apteryx australis mantelli ) eggs, 24 great spotted kiwi ( Apteryx haastii ) eggs and 25 little spotted kiwi ( Apteryx owenii ) eggs. North Island brown kiwi outdoors had an annual cycle of egg-laying with 88.5% of eggs laid from June to January. Eggs were laid in every month of the year, with fewest eggs in April (2.1 % of all eggs). The greatest number of eggs was laid in July (15.6% of all eggs), with a second peak of laying in October (13.5% of all eggs). Both the great spotted kiwi and little spotted kiwi had annual cycles of egg-laying, with the main egg-laying seasons being August-January (87.5% of eggs) for the former and July-December (96.0% of eggs) for the latter. The highest peaks of laying were in October and August, respectively. Kiwi eggs were considered to belong to the same clutch if they were laid no more than 40 days apart. Clutch size in the North Island brown and little spotted kiwi was most commonly one or two eggs. In the great spotted kiwi only clutches of one egg were found. The mean clutch size of North Island brown kiwi outdoors (1.51±0.05) did not differ from that of free-living North Island brown kiwi (1.33±0.09). Similarly, there was no difference in the mean clutch size of captive and free-living little spotted kiwi (1.39±0.14 and 1.10±0.07). The mean interval between eggs for kiwi outdoors did not differ between North Island brown kiwi and little spotted kiwi (27.4±0.5 and 30.7±1.8 days). The results indicate that all three species of kiwi maintain annual cycles of egg-laying in captivity, with the main egg-laying season being longer than in free-living birds.     

Bipedal locomotion in ratites (Paleognatiform): examples of cursorial birds

The gaits of five Ostriches Struthio camelus , seven Emus Dromaius novaehollandiae, two Greater Rheas Rhea americana, two Southern Cassowaries Casuarius casuarius and one Brown kiwi Apteryx australis were filmed at zoological parks. Locomotor parameters were measured using footprints on sandy tracks and video records. Osteological measurements were made on skeletons of the pelvic limbs. All of these terrestrial birds shift from wallking to running at a relative speed below 1. However, they show two different locomotor patterns: the Brown Kiwi increases its speed by increasing its stride length, mainly by increasing the protraction angle. Its hindlimbs make a flexed jointed chain system, its centre of mass is anterior, its femurs are long and the knees act in yield whereas the distal joints act in propulsion. Other ratites, particularly Ostriches, increase their speed by increasing frequency. Their centre of mass is close to the hip, their hindlimbs have an extended jointed chain system with a short erect femur, maximizing a gravity-powered system.     

Application of the index of marsh bird community integrity to coastal wetlands of Georgian Bay and Lake Ontario,Canada

Ecological indicators have gained increasing attention within the scientific community over the past 40 years. Several taxonomic groups have been used successfully as indicators including most prominently fish, invertebrates, plants, and birds because of their ability to indicate environmental changes. In the Laurentian Great Lakes region, there has been recent concern over the applicability of using indicators on a basin-wide scale due to species range restrictions and lake-based differences. The objective of this study was to determine the ability of the Index of Marsh Bird Community Integrity (IMBCI) to indicate land use disturbance surrounding coastal marshes of Georgian Bay and Lake Ontario. To meet this objective, we surveyed birds and vegetation at 14 marshes in Georgian Bay (low land use disturbance) and Lake Ontario (high land use disturbance). Even though Lake Ontario marshes were surrounded by significantly more altered land than Georgian Bay marshes, and had poorer water quality, we found significantly fewer birds in Georgian Bay marshes (mean = 8.2) compared to Lake Ontario (mean = 13.7) and no significant difference in IMBCI scores. This inconsistency could be due to vegetation differences affecting the strength of the index, because Georgian Bay wetlands had significantly more bulrush (Schoenoplectus spp.) and floating vegetation, while Lake Ontario wetland vegetation was taller and cattail-dominated (Typha spp.). These findings suggest that the IMBCI may not be useful on a basin-wide scale in the Great Lakes region in detecting human disturbance surrounding wetlands.     

The secret life of wild brown kiwi: studying behaviour of a cryptic species by direct observation

Kiwi possess many unusual features that make them interesting subjects for behavioural study. However, their nocturnal, cryptic nature has meant that studies to date rely on data collected indirectly. Infrared technology has enabled us to observe kiwi directly and here we present the first study of wild brown kiwi (Apteryx mantelli) behaviour by direct observation. We used handheld infrared video cameras to obtain c.?6 hours of video footage of kiwi over 19 months. Kiwi used native forest and exotic pasture habitats while active at night and spent most of their time foraging (75%). Prey capture rates were significantly higher in pasture than forest. The remaining 25% of time was spent walking, vigilant, engaged in comfort behaviours, escaping disturbance, and investigating obstacles. Direct social and courtship interactions were observed rarely. The senses of hearing, olfaction and touch seemed most important to kiwi. Touch was used for investigating terrain and negotiating obstacles. Hearing was used in response to sounds made by observers, conspecifics and other sources. Olfactory search behaviours (OSBs) were used in the direction of these sounds, and olfaction was also apparently used to assess odours on the ground. We observed no behaviours that appeared to be guided by vision. Behavioural repertoire size and diversity increased in winter, due to increases in OSBs towards conspecifics and other odour sources, and rarely observed behaviours. Prey capture rates also increased near-significantly in winter and microhabitat use was more diverse. Female kiwi at our study site had 30% longer bills than males, and probed into soil substrates on average 30% deeper. No other fine-scale behaviours that might reduce competition between kiwi sexes were observed.     

Nuclear microsatellite DNA markers for New Zealand kiwi (Apteryx spp.)

Kiwi (Apterygidae) is an endemic New Zealand avian family comprising five species whose conservation is actively managed. We present five polymorphic microsatellite DNA loci isolated from North Island brown kiwi (Apteryx mantelli). In addition, we demonstrate cross‐amplification, and in some cases, polymorphism, of these microsatellite DNA loci in four other kiwi species. Therefore, these markers may be broadly applicable to conservation genetic studies within this family.     

Size matters: predation risk and juvenile growth in North Island brown kiwi (

This study investigated how predation risk in North Island brown kiwi changes as the birds grow and develop. Over a 10-year period, 53 adult and 126 young kiwi were radio-tagged at Lake Waikaremoana and studied to determine survival rates, causes of death, and rates of growth. Predation loss amongst adults was low (2.49% year^-1) and caused mainly by ferrets. Young kiwi suffered intense predation from stoats during their first four months of life, but thereafter became too large (> 800 g) for stoats to kill. Juveniles took at least 880 days to attain adult size, about four times longer than expected for a 2–3 kg bird. Growth rates peaked at about the point of hatch, rather than later on in development as in other birds. We suggest that a long evolutionary history dominated by resource limitation rather than predation may account for slow rates of development in kiwi, and that differences among kiwi species in their ability to persist in the presence of stoats are explained by differences in the time that they take to reach safe-size.     

Focusing and accommodation in the brown kiwi (Apteryx australis)

Summary Brown kiwis are an endangered species of nocturnal, flightless birds which are native to New Zealand. The resting focus of two specimens has previously been studied by retinoscopy in a zoo while the birds were restrained by their keeper (Sivak and Howland 1987). Those birds appeared to be hyperopic (farsighted) by 2–7 D. In this study, examination with infrared photorefraction of the focusing of two unrestrained, feeding birds showed that they could focus objects at infinity and objects in their immediate environment and that they had modest powers of accommodation. Measurements on two 6 month old kiwi chicks showed their corneal radius of curvature to be between 2.90 and 3.00 mm (117 D and 101 D in power).     

Artificial weta roosts: A technique for ecological study and population monitoring of Tree Weta (

Tree weta (Hemideina) are an important component of New Zealand forest ecosystems and have been identified as possible invertebrate indicator species in restoration programmes. We present designs for artificial weta roosts that have been used to monitor tree weta in Hawke's Bay for five years. A variety of invertebrates use the roosts including two species of Hemideina. Our data suggest that occupation of roosts may take a number of years, each roost monitors a very limited area, and that occupation by invertebrates fluctuates seasonally. We recommend that data from weta roosts be used primarily for temporal rather than spatial comparisons, and that installation of roosts takes place as far ahead of changes in management as feasible.     

The peculiar structural features of kiwi fruit pectin methylesterase: amino acid sequence, oligosaccharides structure, and modeling of the interaction with its natural proteinaceous inhibitor

Pectin methylesterase (PME) from kiwi fruit (Actinidia deliciosa) is a glycoprotein, showing an apparent molecular mass of 50 kDa upon size exclusion chromatography and SDS-PAGE. The primary structure, elucidated by direct sequencing of the protein, comprises 321 amino acid residues providing a molecular mass of 35 kDa. The protein has an acetylated Thr residue at the amino terminus and five N-glycosylation consensus sequences, four of which are actually glycosylated. A careful investigation of the oligosaccharide structures demonstrated that PME glycans belong to complex type oligosaccharides essentially consisting of xylosylated polyfucosylated biantennary structures. Alignment with known mature plant PME sequences indicates that the postulated active site residues are conserved. Kiwi PME activity is inhibited following the interaction with the proteinaceous inhibitor PMEI, isolated from the same source. Gel-filtration experiments show that kiwi PME/PMEI complex is stable in a large pH range and dissociates only at pH 10.0. Modeling of the interaction with the inhibitor was performed by using the crystal structure of the complex between kiwi PMEI and tomato PME as a template. The model shows that the binding site is the same reported for tomato PME. However, additional salt link interactions are found to connect the external loops of kiwi PME to PMEI. This finding may explain the higher pH stability of the complex formed by the two kiwi proteins respect to that formed by PMEI and tomato PME.     

Sufficiency of horseshoe crab eggs for red knots during spring migration stopover in Delaware Bay USA

Horseshoe crab (Limulus polyphemus) eggs are a dietary staple of the red knot (Calidris canutus) during its spring stopover on the Delaware Bay. Numbers of knots stopping in Delaware Bay declined in the 1990s concurrent with a decline in horseshoe crabs, leading to the hypothesis that reduced horseshoe crab egg abundance limited the red knot population. Management efforts, including a seasonal harvest moratorium in the Delaware Bay, have been instituted to restore crab populations to levels of sustainable use by multiple users, including migratory birds. Our objective was to evaluate the sufficiency of horseshoe crab eggs in Delaware Bay in May–June 2004 and 2005 for knots to refuel for their migratory flight to the Arctic breeding grounds. We examined egg counts to determine if there were fewer high egg-density sites later than earlier in the day and season, as migrating birds might deplete this resource. We studied foraging rates at red knot locations to determine if foraging probes increased with time of day and season as birds depleted surface eggs by pecking, then began probing for subsurface eggs. Finally, we experimentally tested whether red knots and their competitors depleted horseshoe crab eggs. Crab egg numbers at knot foraging sites did not decline throughout the day or season in 2004. In both years, we found no evidence that knots switched from pecking to probing with increases in time since sunrise or start of the stopover. Egg numbers were similar in exclosed and accessible plots on crab nesting depressions and in areas of open intertidal zone, but were significantly lower in accessible than in exclosed plots in the wrack line. Our results indicate that horseshoe crab eggs in Delaware Bay were sufficient to support the refueling of the present-day stopover population of red knots. If an increase in the availability of crab eggs to foraging birds does not result in an increase in knot numbers, managers must prioritize mitigation of limiting factors at other historically important spring stopovers and on the poorly understood breeding and wintering grounds in addition to the Delaware Bay. © 2011 The Wildlife Society.     

The status and recent breeding performance of the critically endangered Northern Bald Ibis Geronticus eremita population on the Atlantic coast of Morocco

The main wild population of the Northern Bald Ibis Geronticus eremita breeds on the Atlantic coast of Morocco in the Agadir region. This paper describes the numbers of breeding pairs over the last two decades, the recent breeding performance, the causes of egg and chick losses and their conservation implications. Since 1980 there has been no overall decline in numbers with, over the last 5 years, 59–74 pairs breeding and a peak prebreeding population of around 220 birds. In contrast with the now extinct Northern Bald Ibis populations in Turkey and elsewhere in Morocco, the birds are present in the Agadir region throughout the year and do not appear to migrate from the area outside the breeding season. Breeding performance is highly variable from one year to the next but does not appear to be related to rainfall in the vicinity of the colonies as has been reported elsewhere. It is suggested that coastal fogs in this region may buffer the adverse impacts of low rainfall and may in part account for the year-round residency of the birds. The main causes of breeding failures have been loss of eggs to predators and, most importantly, poor chick survival as a result of starvation and predation. Conservation action to date has focused on reducing the negative influences on breeding success but it is recognized that for such a long-lived bird adult survival is also likely to be an important limiting factor on the population size.     

Forest bird mortality and baiting practices in New?Zealand aerial 1080 operations from 1986 to 2009

We collated 48 surveys of individually banded birds or birds fitted with radio transmitters that were checked before and after 1080 poison (sodium fluoroacetate) baits were aerially distributed to control brushtail possums (Trichosurus vulpecula) in New?Zealand forests. The surveys were associated with 34 pest control operations from 1986 to 2009 and covered 13 native bird species, of which four were kiwi (Apteryx spp.). Sample sizes ranged from 1 to 46 birds (median 15). In 12 cases a sample of 1 to 42 birds (median 13) was surveyed in an untreated area at the same time. In total, 748 birds were checked before and after operations and 48 birds disappeared or were found dead. In non-treatment areas, 193 birds were checked and four died. Surveys of kiwi, whio (Hymenolaimus malacorhynchos), kaka (Nestor meridionalis) and kokako (Callaeas cinerea) were grouped for meta-analyses. The 95% pooled upper confidence bounds for the point estimate of zero mortality were each less than 4% for kiwi, kaka and kokako indicating only a small risk of mortality during 1080 pest control operations. Prefeeding with non-toxic baits increased from 22% (1998?1999) to 79% (2007?2008) in 322 operations on public conservation lands but was used in only 9 (26%) of the operations during which individually marked birds were monitored. We caution that failure to observe bird deaths in small samples may lead to weak inference about zero mortality across a population, most surveys in the review did not involve prefeeding, and that 11 native bird species for which deaths were reported after 1080 operations have not been studied.