Parrot Nests Research Articles

Long‐term ecological data confirm and refine conservation assessment of critically endangered swift parrots

AbstractConservation assessments of threatened species are often limited by scarce data and parameter uncertainty. Predictive models, designed to incorporate this uncertainty, may be the only tool available to inform conservation assessments for data‐deficient species, but they are used surprisingly rarely for this purpose. The swift parrotLathamus discoloris the only critically endangered bird to be listed in Australia based on population viability analysis (PVA). We aimed to evaluate the accuracy of the 2015 conservation assessment, which used sparse information, by incorporating new detailed and long‐term data. First, we updated a range of life history parameter estimates, and then we repeated the same PVA as per the original conservation assessment. This process confirmed our earlier finding that swift parrot nests were more likely to survive in places with high mature forest cover. We identify that high forest landscape integrity and abundant hollow‐bearing trees best predict nest daily survival rates. Based on the updated PVA, we predict a 92.3% population decline over three generations (11 years). This supported the predictions of the original conservation assessment, and the main benefit of the additional data was improved confidence in projections (the magnitude and direction of the population decline were similar between the original and updated PVAs). Our results demonstrate that meaningful trends can be inferred for species with imperfect information about their life history. Using predictive models like PVAs can help managers identify which life history parameters impact most on demographic trends. This information can guide targeted data collection so that ‘draft’ models can be later updated to improve certainty around population predictions.

The impact of timber harvesting on nest site availability for the Cape Parrot Poicephalus robustus in native Southern Mistbelt forests of the Eastern Cape, South Africa

Summary The Amathole mistbelt forests in the Eastern Cape, South Africa harbour the largest remnant population of the nationally endangered endemic Cape Parrot Poicephalus robustus, a secondary-cavity nester whose persistence is limited by suitable nest sites. These are also the only forests within Cape Parrot range in which selective timber harvesting remains permitted, but the impact of harvesting on the availability of parrot nest sites has not been investigated. This study aimed to determine the degree to which current harvest selection criteria stand to impact nest site availability. Results showed that Cape Parrots have specific nest tree requirements; and that there is overlap in the species and condition of trees selected for nesting, and harvesting. The two yellowwood species found in the region, Afrocarpus falcatus and Podocarpus latifolius, represented the majority of both harvested trees (78%), and Cape Parrot nest trees (79%). Moreover, both Cape Parrot and harvest selection criteria require large (≥50 cm diameter at breast height; ≥12 m high), old, dead, dying, or crown-damaged yellowwoods, such that 32% of trees considered potential nest trees were also candidates for harvesting. Current selection criteria need to be revised to ensure that timber use is compatible with biodiversity conservation in the Amathole forests. We suggest that all harvesting of dead standing yellowwoods be discontinued; and that the harvesting of live trees with crown damage, which are frequently used by parrots for nesting, be limited by a species-specific maximum harvestable diameter.

Productivity constraints on Citron-crested Cockatoos in a rich community of large hole-nesting birds

Knowledge of breeding success and its limiting factors is crucial in assessing species’ conservation needs. As cavity-nesters, parrots are particularly influenced by the availability of suitable cavities and low breeding output, whether due to natural processes or trapping. On the island of Sumba, Indonesia, the Critically Endangered Citron-crested Cockatoo (Cacatua citrinocristata) has the added problem of co-existing with an unusually rich hole-nesting bird community in a forested environment much constrained by habitat loss. We monitored 95 nesting cavities of cockatoos and their competitors and potential nest-predators, over one to four breeding seasons, using a combination of camera-traps, direct checks on nest contents, and observations from the ground. Competition for suitable cavities was intense among three large parrot species, two owls and a hornbill. Visitation rates by potential competitors were higher at unoccupied cavities than at those containing active nests, reflecting the guarding behaviour of the occupants. The Endangered Sumba Hornbill (Rhyticeros everetti) dominated observed direct confrontations and was the most frequent visitor to active parrot nests, suggesting a further role as a potential nest-predator. Cockatoos prospected many cavities but rarely then attempted to nest: instead the sites were usually occupied by other cavity-nesters, or by bees. At the few cavities where cockatoos did breed, predation pressure was likely low, and observed success rate high (10 successful of 15 nests), although the low number of nests found early in the breeding cycle suggests that some may have failed before detection. Intense competition for cavities suggests a shortage of suitable nest-sites, the need for preservation of old hole-bearing trees and a role for nestboxes. Accessible, known, safe artificial nest-sites would also provide opportunities to assess the scale of nest-site shortage, allow camera placements to study productivity, exclude some competitors and predators, and prevent illegal trapping. Especially given continued trapping pressure, the species would benefit from targeted local awareness-raising and law enforcement, with the whole endeavour backed up by longer-term forest restoration.

Carcasses attract invasive species and increase artificial nest predation in a desert environment

In addition to feeding on animal remains, many scavengers also function as predators. Carcasses may therefore affect local animal communities by attracting facultative scavengers and increasing predation risk for other species in the vicinity of the carcasses. This risk may be elevated in low productivity environments, especially where humans increase carcass production and where facultative scavengers include invasive species. In June and October 2018, we monitored experimentally placed red kangaroo (Osphranter rufus) carcasses and artificial bird nests in two different habitats in the Simpson Desert, Australia, to identify the nest predators attracted to the carcasses, and to determine how carcasses affect overall and predator-specific nest predation. We modelled our nests to approximate those of the ground nesting little buttonquail (Turnix velox) and the endangered night parrot (Pezoporus occidentalis). Native Corvus spp. and then invasive red foxes (Vulpes vulpes) were the top carcass visitors and nest egg predators. Carcass presence and open habitat increased overall nest predation and fewer artificial parrot nest eggs were depredated compared to those of quail. Open habitat and carcass presence only increased predator-specific nest predation by foxes, but corvid nest predation was highest in June 2018, and for the artificial quail nest types. Foxes were the main predator of eggs from night parrot nests. Our study shows that carcass provisioning by humans may have indirect, deleterious effects on ground nesting birds, and indicates that foxes might pose a greater threat to night parrot populations than previously recognised.

Evaluation of lethal control of introduced sugar gliders as a tool to relieve bird nest predation

Lethal control of invasive mammalian predators can be controversial and is rarely a ‘silver bullet’ for conservation problems. Evaluating the efficacy of lethal control is important for demonstrating the benefits to threatened species are real and detecting unexpected perverse outcomes. We implemented a pilot study to evaluate if lethal control of introduced sugar gliders Petaurus breviceps can reduce the rate of nest predation on Tasmanian hollow nesting birds including swift parrots (Lathamus discolor). Using a before-after-control-impact design, we implemented a lethal control treatment whereby we attempted to remove sugar gliders from three treatment sites. In each time period across sites we monitored quail eggs in nest boxes to record predation, and used cameras to detect sugar gliders. We caught nine sugar gliders over three treatment sites. The model best supported by the data indicated an effect of site×time period on both egg survival and the rate of glider detection on cameras. There was no support for an effect of treatment on our data. We also recorded predation of a real swift parrot nest by sugar gliders at a treatment site where we recorded no predation of quail eggs. Our pilot study shows that at small scales, intensive lethal control of gliders yields low capture rates and no discernible effect on the metrics we measured. We conclude that alternative approaches to controlling the impact of sugar gliders, such as habitat protection, are critical in this study system before lethal control is widely implemented as a management tool.

Suitable nesting sites for specialized cavity dependent wildlife are rare in woodlands

Non-excavating species that prefer rare combinations of cavity traits are limited to only a fraction of the available tree cavity resource. Understanding animal preferences and quantifying the abundance of suitable cavities is fundamental to protecting non-excavators. We aimed to identify the traits of trees and cavities selected by a vulnerable, non-excavating bird, the superb parrot Polytelis swainsonii. We also evaluated cavity abundance and the accuracy of ground-based survey techniques (where an observer estimated the number of cavities in the canopy with binoculars from the ground). We then climbed trees to accurately identify true cavities and to measure their internal dimensions. Ground-based counts of tree cavities were correlated with the true number of cavity entrances in trees. When trees had zero cavities, ground counts overestimated their abundance, but for cavity-bearing trees ground counts underestimated their abundance. We found that superb parrot nest trees contained more cavities than random trees. Superb parrots selected cavities that were deeper, with wider floors and entrance sizes than random cavities. Cavities with the combination of selected traits comprised only 0.5% of the standing cavity resource. Our results confirm that non-excavators can be very selective about the types of trees and cavities they use for nesting. Rarity of suitable cavities may be a factor limiting the population growth and recovery of superb parrots. Without accounting for the critical information gap between what is observed on the ground, and what is in fact present in trees, effective habitat management for non-excavators may be compromised by inaccurate assessments of cavity abundance and conservation status.

Breeding biology of three large, sympatric rainforest parrots in New Guinea: Palm Cockatoo, Pesquet’s Parrot and Eclectus Parrot

ABSTRACT In New Guinea Palm Cockatoos, Pesquet’s Parrots and Eclectus Parrots are potentially threatened by deforestation and hunting. In a 28-month study, we found 51 Palm Cockatoo, 34 Pesquet’s Parrot and 71 Eclectus Parrot nests. Eclectus Parrots used taller, larger, live trees. Palm Cockatoos preferred hollows in broken trunks having deeper hollows with larger entrances. Pesquet’s Parrots excavated their nest hollows in dead trees. Palm Cockatoos nested at lower density (0.008 nests/ha) than Pesquet’s (0.022 nests/ha) and Eclectus Parrots (0.069 nests/ha). Palm Cockatoos and Pesquet’s Parrots appeared to breed seasonally; Eclectus Parrots bred at higher frequency year-round. Palm Cockatoo clutch size was one; Pesquet’s and Eclectus Parrots clutches had one to two eggs. Eclectus Parrots had higher fledging success: 54%, compared with 40% of Palm Cockatoo and 17% of Pesquet’s Parrot eggs. Predation caused most nest failures for Palm Cockatoos and Eclectus Parrots; starvation caused most loss in Pesquet’s Parrots. Humans hunted Palm Cockatoos and Pesquet’s Parrots, not Eclectus Parrots. Higher nest tree density, breeding success, and more generalised feeding habits may make Eclectus Parrots the least vulnerable of the three species. Low population density and breeding frequency of Palm Cockatoos and Pesquet’s Parrots may make them more vulnerable.

Heterospecific competition in a threatened cavity-nesting parrot: a case study of the eastern Regent Parrot (Polytelis anthopeplus monarchoides)

ABSTRACTNest cavities are a limited resource, given the extensive land clearance that has occurred in Australia. Some obligate cavity-nesting birds are vulnerable to extinction and experience risk from heterospecific species that compete for limited nest cavities. The aim of this study was to identify intruder bird species at nest cavities of a threatened eastern subspecies of Regent Parrot (Polytelis anthopeplus monarchoides), and to measure the impact of intruder birds on parental care (parental time budgets) and nesting outcome (nest usurpation). We observed 25 eastern Regent Parrot nests using a combination of 608 h of video recording and 67 h of binocular observation. In total, we observed 16 heterospecific bird species at the nest entrance of the eastern Regent Parrot. Two of these species were examined for their impact on parental care behaviour. The presence of Noisy Miners (Manorina melanocephala) near the nest cavity increased the time that Regent Parrots spent at the nest cavity entrance. The number of Yellow Rosella (Platycercus elegans flaveolus) visits to the nest cavity predicted nest usurpation. Nest usurpation of a Regent Parrot nest occurred in 6/25 cases (24%), of which 5/6 nests were usurped by Yellow Rosellas. Understanding heterospecific competition for nest cavities in eastern Regent Parrots should inform targeted conservation measures.

Sex ratio bias and shared paternity reduce individual fitness and population viability in a critically endangered parrot.

Sex-biased mortality can lead to altered adult sex ratios (ASRs), which may in turn lead to harassment and lower fitness of the rarer sex and changes in the mating system. Female critically endangered swift parrots (Lathamus discolor) suffer high predation while nesting due to an introduced mammalian predator, the sugar glider (Petaurus breviceps). High predation on females is causing severe population decline alongside strongly biased adult sex ratios (≥73% male). Our 6-year study showed that 50.5% of critically endangered swift parrot nests had shared paternity although the birds remained socially monogamous. Shared paternity increased significantly with the local rate of predation on breeding females, suggesting that rates of shared paternity increased when the ASR became more biased. Nests that were not predated produced fewer fledglings as the local ASR became more male-biased possibly due to higher interference during nesting from unpaired males. Population viability analyses showed that part of the predicted decline in the swift parrot population is due to reduced reproductive success when paternity is shared. The models predicted that the population would decline by 89.4% over three generations if the birds maintained the lowest observed rate of shared paternity. This compares with predicted population reductions of 92.1-94.9% under higher rates of shared paternity. We conclude that biases in the ASR, in this case caused by sex-specific predation from an introduced predator, can lead to changes in the mating system and negative impacts on both individual fitness and long-term population viability.

Effect of nest cavity morphology on reproductive success of a critically endangered bird

ABSTRACTPopulation limitation is the outcome of cumulative and synergistic processes that act on species over multiple spatial scales. Tree cavity dependent animals are good case studies for exploring processes that potentially limit populations across multiple scales. Fine-scale cavity characteristics have important consequences for predator exclusion and fecundity, while broad-scale processes (food or habitat availability) can determine population viability. We considered the relative importance of cavity morphology in limiting the breeding success of a critically endangered secondary cavity nesting bird that is severely affected at broad scales by nest predation. Swift Parrots (Lathamus discolor) select nest cavities where the minimum entrance diameter is positively associated with cavity depth, floor diameter and maximum entrance diameter. These cavity characteristics are adaptive because they exclude native predators by physically preventing access to the nest chamber; only one introduced nest predator is able to overcome this passive nest defence. Introduced Sugar Gliders (Petaurus breviceps) could prey on Swift Parrot nests irrespective of nest cavity morphology. We found no effect of cavity morphology on the number of eggs laid or fledglings reared by Swift Parrots. This suggests that fine-scale nest cavity characteristics do not influence the nest success of Swift Parrots beyond their effectiveness in excluding native Tasmanian predators.

Lophozonia tree cavities used for nesting by Slender-billed Parakeets (Enicognathus leptorhynchus) in the central valley of southern Chile: a potentially vanishing keystone resource

BackgroundThe Slender-billed Parakeet (Enicognathus leptorhynchus) is a psittacine endemic to southern Chile and an obligate secondary cavity-nester. In the central valley of southern Chile, most (94%) of the known Slender-billed Parakeet nests have occurred in large, mature southern beech (Lophozonia obliqua) trees (locally known as “pellines”). As relicts of the original old-growth forests of southern Chile, most pellines have been lost due to extensive land-clearing throughout the region, potentially threatening long-term persistence of the Slender-billed Parakeet.MethodsWe conducted our study in the central valley of southern Chile, near the city of Osorno during three consecutive nesting seasons (November–January, 2008–2011). Nest trees used by Slender-billed Parakeets were located by direct observation of parakeet activities and through interviews with local residents, some of whom were former parrot nest poachers. Nest cavities were accessed, inspected and measured using single-rope climbing techniques. We report means, standard errors, 95% confidence intervals and ranges for 11 cavity-related variables. We also report clutch sizes encountered in active nests, and age estimates of nest trees based on known growth rates of Lophozonia trees in southern Chile. Linear regressions were used to evaluate potential relationships between cavity-related variables and clutch size.ResultsWe located and measured 38 Lophozonia tree cavities used for nesting by Slender-billed Parakeets. Compared to those used by other psittacines, nest trees were relatively large, averaging 30.4 ± 1.1 m in height with a mean diameter at breast height of 134.5 ± 4.7 cm. Based on estimated annual diameter increment, ages of nest trees ranged from approximately 209–485 years. Nest cavities entrances averaged 12.5 ± 0.9 m in height above ground level. Cavity entrance widths averaged 51.0 ± 13.3 cm (vertical) by 11.5 ± 0.7 cm (horizontal). Cavity entrance orientations were apparently random, with no directional preferences detected. Nest cavities were also relatively large, with a mean internal diameter of 39.6 ± 2.4 cm and mean depth of 90.3 ± 24.2 cm. Clutch sizes (2–9) were unusually large for psittacines of this size (ca. 280–300 g) and broods of up to seven well-developed nestlings were observed.ConclusionsWe found that the deep and spacious cavities provided by pellines facilitate successful rearing of large broods, thereby maximizing productivity and fitness. The existence of pellines has apparently allowed Slender-billed Parakeets to adapt successfully to a wholesale loss of ancestral habitat to anthropogenic modifications. Immediate and strategic conservation measures, such as protection of existing pellines and the regeneration and recruitment of additional ones, are recommended for ensuring the survival of Slender-billed Parakeet populations throughout the central valley of southern Chile.

Piecing the puzzle together: the fate of the Night Parrot nest found in Western Australia by Jackett et al. (2017)

Characteristics of a Night Parrot nest in the East Murchison region of Western Australia are documented. This nest failed, most likely either due to predation or abandonment. Human disturbance is ruled out as a cause. However, we recommend that human activity near Night Parrot nests is minimised, to avoid unnecessary disturbance to breeding attempts in this Critically Endangered species.

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The study was initiated to gather data on nest preferences of the Grey Parrot in Cameroon. Knowledge on nesting preferences of the parrot can be implemented in the field and captivity to improve on the breeding of Grey Parrots. The Kom National Park-Mengame Gorilla Sanctuary complex was chosen as a representative site in the country. A total of 40 sample plots of size 200 m x 200 m were randomly established and distributed to represent major vegetation types in the area. Line transects were established in each sample plot and data on nest characteristics were collected along them. Results revealed that nests were found in 14 tree species belonging to 12 families with high preferences for Terminalia superba (84%). Nest density varied between 0.23 to 0.45 nests/ha in various vegetation types and the highest density was recorded in the secondary forest. Nests entrance varied with a mean length of 13.2 ± 6.0 cm and a majority of them were rounded (85.42%) in shape. Nest concealment varied with tree height, 35.4 ± 6.1 m); trunk diameter, 90.8 ± 23,6 cm; height of nest from the ground 22.1 ± 6.4 m and canopy diameter,18.0 ± 6.1 m. Most nests of Grey Parrots were found in secondary forest (32.72%). The Grey Parrots tolerated degraded vegetation with suitable nests in nearby villages and were not, threatened through hunting and poaching activities from villagers. It strongly recommended that, villagers should learn to co-habitat with the Grey Parrot in their villages to enhance long-term survival of the bird species in the wild.   Key words: Grey Parrot, Psittacus erithacus, grey parrot nest, nest site, nest characteristics, parrot conservation.

Loss of habitat for a secondary cavity nesting bird after wildfire

Tree cavity dependent animals are sensitive to changes in cavity availability in forests. Fire is important in the long-term dynamics of cavity creation and loss, but there are few data on how fire impacts nesting resource availability for animals. We assessed the survival of 189 trees and 191 cavities used for nesting by an endangered secondary cavity nesting bird, the swift parrot Lathamus discolor, over a decade. A subset of monitored trees were burned in an uncontrolled fire. At the site of that fire, we compared swift parrot habitat quality before and after burning. We also evaluated the risk of total tree collapse due to stem destabilisation from basal scarring by calculating the critical failure stress for all monitored trees. Modelled persistence of unburned swift parrot nest cavities was more than twice that of scorched cavities over ten years. Likewise, unburned nest trees were more likely to still be standing at the end of the ten years than scorched trees. Fire caused an acute local increase in cavity and tree collapse. At the site of the fire, 62.8% of scorched nest cavities were destroyed compared to only 9.1% over the unburned remainder of the study area. Likewise, 48.6% of scorched nest trees collapsed at the fire affected site, compared to only 3.8% of unburned trees elsewhere. Burning associated tree collapse led to a significant decrease in tree diameter at breast height and number of potential cavities at monitored plots. This destroyed most of the existing nest cavity resource for swift parrots at the local scale and cavity abundance is unlikely to be replenished quickly. Loss of nesting resources may outweigh longer-term benefits of fire as an agent of cavity creation if animals miss opportunities for reproduction in locations where habitat is diminished by cumulative stochastic events and anthropogenic changes.

A push-pull integrated pest management scheme for preventing use of parrot nest boxes by invasive Africanized honey bees

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Effects of landscape composition and connectivity on the distribution of an endangered parrot in agricultural landscapes

The extent and connectivity of individual habitat types strongly affects the distribution and abundance of organisms. However, little is known of how the level of connectivity and the interactions between different habitat types influences the distribution of species. Here, we used the geographically restricted and endangered regent parrot Polytelis anthopeplus monarchoides as a case study to examine the importance of composition and connectivity between different elements in 39 complex landscape mosaics (each 10 km radius). We compiled a database of 674 regent parrot nesting records, regional vegetation maps and measures of multipath connectivity between core vegetation types under different scenarios of resistance to movement provided by landscape elements. The occurrence of regent parrot nests was strongly affected by landscape composition, being positively related to the extent Eucalyptus camaldulensis riverine forest, but negatively related to the extent of semi-arid woodlands dominated by Eucalyptus largiflorens. Connectivity between E. camaldulensis forest (principal nesting habitat) and mallee (preferred feeding habitat) was a strong predictor of nest locations. Our study shows that the suitability of fragmented agricultural landscapes for supporting species can be greatly affected by connectivity and interactions between preferred and non-preferred habitats. For species that require complementary habitats such as the regent parrot, conservation management activities may be ineffective if they simply focus on a single core habitat type or the impacts of human land uses without regard to the interrelationships among landscape elements. While increasing the amount of primary preferred habitat should remain a cornerstone goal, increasing the extent and improving connectivity with alternative landscape elements also should be priority management objectives.

Nesting requirements of the endangered Swift Parrot (Lathamus discolor)

Declines in avian biodiversity are being reported worldwide. A better understanding of the ecology of many species is fundamental to identifying and addressing threatening processes and developing effective mitigation measures. The Swift Parrot (Lathamus discolor) is listed as endangered and is an obligate migrant that breeds only in Tasmania, wintering in mainland Australia. The species nests in tree-hollows and forages primarily on flowers of the Tasmanian Blue Gum (Eucalyptus globulus) and Black Gum (Eucalyptus ovata) during the breeding season. Surveys for Swift Parrot nests conducted over three consecutive breeding seasons identified 130 Swift Parrot nests in 117 trees. Sites were between 12 and 130 ha in area with up to 49 nests found at an individual site. Swift Parrot nest-trees were characterised as being large eucalypts (mean diameter at breast height = 105 cm) with five or more potential hollows (mean = 8.6) and showing clear signs of senescence. Reuse of nests was uncommon over the 3 years and the infrequency of reuse was most likely related to poor flowering of Tasmanian Blue Gums around nesting sites in years following recorded nesting. To protect the species, conservation actions need to account for the spatiotemporal variation in the availability of Swift Parrot breeding habitat and recognise there may be several years between the use of a particular site. Given the number of nests found at individual sites this will require the management or reservation of suitable forest stands with old-growth characteristics across the landscape, rather than focussing on individual trees or historical nesting sites.

First Finding of Melanic SylvaticTriatoma infestans(Hemiptera: Reduviidae) Colonies in the Argentine Chaco

Triatoma infestans (Klug), the most important vector of Chagas disease in southern South America, is a highly domiciliated species with well-known sylvatic foci only in the Bolivian Andean valleys and in the Bolivian Chaco, where melanic insects designated as "dark morphs" were found. After the tentative identification of two melanic bugs collected from parrot nests in a forest reserve in the Argentine Chaco as T. infestans, we conducted an intensive search there using mouse-baited sticky traps in summer 2006 and 2007. Four live T. infestans bugs were collected in trees without parrot nests in 288 trap-nights, whereas no bug was collected from inside trees with active parrot nests in 51 trap-nights. To increase bug captures, hollow tree trunks that recently had had Amazona aestiva (Berlepsch) and Aratinga acuticaudata (Vieillot) parrot nests were treated with insecticide fumigant canisters exhibiting strong knockdown power. Four (22%) of 18 trees were positive for T. infestans with a dark phenotype. A fragment of the mitochondrial gene COI of 8 of the 14 triatomine bugs collected was successfully sequenced and confirmed as T. infestans. Most of the bugs were captured from Aspidosperma quebracho-blanco (Schlechter) hollow tree trunks harboring parrot nests. All of the T. infestans collected from the nearest house located at 10 km from the sylvatic foci displayed normal chromatic characters. The repeated finding of T. infestans in sylvatic habitats, albeit at very low density, shows that this species is capable of maintaining viable sylvatic foci in the absence of human hosts and immigration from domestic populations. These are the first confirmed findings of sylvatic T. infestans colonies in Argentina and of dark morphs in the Argentine Chaco.

Factors Influencing Nest Spacing of a Secondary Cavity-Nesting Parrot: Habitat Heterogeneity and Proximity of Conspecifics

Abstract. Resource availability in a heterogeneous environment and density-dependent processes may influence the spatial distribution of individuals among habitats. The distribution of nests of secondary cavity nesters is rarely clumped because the birds are constrained by the distribution of existing cavities as nest resources. In this study, to evaluate the interplay of environmental and behavioral processes in the spacing of parrot nests, we compared the spatial distribution of active Lilac-crowned Parrot (Amazona finschi) nests with that of all cavities used as nests over 14 years. Parrots reused 42% of cavities, and the frequency of reuse was significantly associated with a previously successful nesting attempt. Positive fitness benefits of cavity reuse may indicate high-quality nest sites that are used more intensively by resident breeding pairs. Spatial-point-pattern analysis indicated that trees used as nests were significantly clustered within 60 m in the three nesting areas, with average distanc...

Nesting Habitat of the Lilac‐crowned Parrot in a Modified Landscape in Mexico

ABSTRACTParrot populations are being increasingly pressured to occupy modified or fragmented landscapes, yet little is known of the habitat requirements of most species, particularly with regard to the effects on breeding habitat. We evaluated nesting habitat of the lilac‐crowned parrot Amazona finschi in the modified landscape of coastal Michoacan in Mexico. We located 90 parrot nests in 12 tree species in Michoacan, with lilac‐crowned parrots presenting a narrow niche‐breadth of tree species used for nesting. Considering an additional 82 nest trees recorded for lilac‐crowned parrots in Jalisco, we determined a 51 percent similarity in cavity resource use by parrots in the two dry forest regions. Overall, the predominant nest tree species with 76 percent of nests were Astronium graveolens, Piranhea mexicana, Brosimum alicastrum, and Tabebuia spp., all characteristic of semi‐deciduous forest. Only 8 percent of nests occurred in trees characteristic of deciduous forest. Parrots utilized large trees with canopy level cavities as nest sites, and preferred conserved semi‐deciduous forest for nesting, with fewer nests than expected in deciduous forest and transformed agricultural land. Nest areas in semi‐deciduous forest occurred on significantly steeper terrain, as remnant semi‐deciduous forest is restricted to steep ridges and canyons. Those parrot nests in modified habitats and forest patches were located near to continuous forest, with nest trees in open agricultural land being significantly closer to continuous forest than nests in disturbed forest patches. These results demonstrate the importance of conserved semi‐deciduous forest as breeding habitat for the threatened, endemic lilac‐crowned parrot, making wild populations of the species vulnerable to the high rate of transformation and fragmentation of tropical dry forest.