Katherine Renton

LILAC-CROWNED PARROT DIET AND FOOD RESOURCE AVAILABILITY: RESOURCE TRACKING BY A PARROT SEED PREDATOR

Abstract The pattern of food resource availability and use by Lilac-crowned Parrots (Amazona finschi) was evaluated in tropical dry forest of the Reserva de la Biosfera Chamela-Cuixmala, western Mexico. Monthly fruiting phenology transects were conducted throughout the year in deciduous and semi-deciduous forest to determine temporal and spatial variability in resource abundance. Resource use by parrots was evaluated through observations of diet and habitat use. There was significant temporal and spatial variability in food resource abundance, with semi-deciduous forest providing greater food resources for parrots during the dry season, whereas food resource abundance increased in deciduous forest during the rainy season. The critical period of food resource scarcity occurred during May–June at the end of the long dry season. Lilac-crowned Parrots were pre-dispersal seed predators, and exhibited high flexibility in diet, incorporating dietary switching, as well as niche-breadth contraction and expansion, which corresponded with temporal variations in food resource availability. There was low overlap in parrot diets between seasons, with parrots exhibiting a narrow food niche-breadth during the late dry season when resource availability declined. Parrots also demonstrated spatial variation in habitat use, corresponding to fluctuations in the availability of food resources in different habitats. This flexibility in foraging enables parrots to closely track and exploit seed resources which exhibit high temporal and spatial variability in abundance.

Climatic variability, nest predation, and reproductive output of Lilac-crowned Parrots (Amazona finschi) in tropical dry forest of western Mexico

Abstract For 1996–2003, we determined reproductive output and success of 70 Lilaccrowned Parrot (Amazona finschi) nests in tropical dry forest of the Chamela-Cuixmala Biosphere Reserve in western Mexico. Only 42% of nests had young that fledged; predation was the main cause of nest failure. Low brood survival in 2000 and 2003 caused significant between-year variation in the probability of nest success during the nestling phase of the nest cycle. Reproductive output of Lilac-crowned Parrots was low, with females producing an average of 0.99 fledglings on an initial investment of 2.6 eggs. The fecundity component of clutch size varied significantly between years, because of the high median clutch size recorded in 2000. Nestling survival also varied significantly between years, creating large interannual fluctuations in reproductive output. The most productive breeding season was 1999, with an average output of 1.7 fledglings on an investment of 2.7 eggs; whereas the poorest breeding season was 2000, with an output of 0.57 fledglings from 3.3 eggs. Loss of reproductive potential was greatest in 2000 and 2003, because of brood reduction through starvation of later-hatched nestlings, with hatching order influencing the probability of nestling survival. Mean number of nestlings per egg-laying female was associated with interannual fluctuations in precipitation resulting from the El Niño-La Niña weather cycle in the Pacific Ocean. Both nest predation and food availability may limit parrot reproduction in tropical dry forests, with populations of threatened species in dry habitats being vulnerable to effects of climatic variability and habitat fragmentation.

Seasonal variation in occurrence of macaws along a rainforest river

Abstract Seasonal variations in occurrence of the Blue-and-yellow (Ara ararauna), Red-and-green (A. chloroptera), and Scarlet (A. macao) Macaw were evaluated in the floodplain rainforest of the Manu Biosphere Reserve, southeast Peru. One-hour surveys of macaws were conducted while traveling along the Rio Manu in a motorized canoe during both the dry and rainy season. There was a significant three-fold decline in the number of macaws encountered during the dry season compared to the rainy season. Encounter rates also varied significantly among macaw species, and may be due to behavioral characteristics or habitat preferences of species. Rapid or short-term surveys used to establish trade quotas and the status of species may be susceptible to biases and inaccuracies resulting from seasonal variations and behavioral characteristics of psittacine species.

AGONISTIC INTERACTIONS OF NESTING AND NONBREEDING MACAWS

Abstract Agonistic interactions of nesting and nonbreeding Blue-and-yellow Macaws (Ara ararauna) were observed in the Manu Biosphere Reserve, Peru, during the nestling phase of the nest cycle in 1988 and 1989. Three nesting pairs of macaws were identified by facial line and tail patterns, and agonistic behavior was categorized as high-intensity or low-intensity interactions. Nesting pairs associated strongly with cavities and perch trees within the nest area, and frequently chased nonbreeding conspecifics from an area of up to 100 m from the nest. In one case, loss of control of the nest cavity and perch trees by a lone nesting macaw to a nonbreeding pair led to infanticide and abandonment of the nest. Agonistic interactions were predominantly intraspecific, and 79% of agonistic interactions by nesting macaws were directed at nonbreeding conspecifics. The frequency of agonistic interactions increased significantly with day of the nesting cycle, being greatest toward the end of the nestling period. Nonbreeding macaws spent significantly more time in trees at the edge of the nest area than in trees within the nest area, and significantly less time within the nest area when nesting pairs were present than when absent. In both years, only 36% of the available cavities within the nest area were utilized by Blue-and-yellow Macaws, though some cavities were utilized by smaller macaw species. Intraspecific interference competition of nesting macaws may exclude potential breeders from investigating cavities, effectively limiting availability where nest sites are clumped in distribution. Interacciones Agonísticas entre Guacamayas Reproductivas y No Reproductivas Resumen. Se llevaron a cabo observaciones de las interacciones agonísticas entre parejas reproductivas y no reproductivas de la guacamaya Ara ararauna en la Reserva de la Biosfera de Manu en Perú, durante la fase de crianza de los pollos en 1988 y 1989. Se identificaron tres parejas de guacamayas por medio del patrón de líneas en su rostro y por la forma de desgaste de la cola, y el comportamiento agonístico fue caracterizado como interacciones de alta y de baja intensidad. Las parejas nidificantes presentaron una fuerte asociación con las cavidades y los árboles de percha dentro del área de anidación, y frecuentemente persiguieron a individuos coespecíficos no reproductivos hasta 100 m fuera del nido. En un caso, una guacamaya reproductiva solitaria perdió posesión de su nido y del árbol de percha frente a una pareja no reproductiva, resultando en el infanticidio de una cría por la pareja no reproductiva, y en el abandono del nido. Las interacciones agonísticas fueron predominantemente de tipo intraespecífico, con el 79% de las interacciones agonísticas por parte de las parejas nidificantes dirigidas a coespecíficos no reproductivos. La frecuencia de las interacciones agonísticas incrementó significativamente con el día del ciclo de anidación, siendo mayor hacia finales del periodo de crianza de los pollos. Las guacamayas no reproductivas pasaron significativamente más tiempo en los árboles alrededor del área de anidación comparando que en los árboles dentro del área de anidación, y permanecieron significativamente menos tiempo dentro del área de anidación cuando las parejas reproductivas estaban presentes que cuando estaban ausentes. En 1998 y 1999, sólo el 36% de las cavidades disponibles fueron utilizadas por A. ararauna, aunque algunas fueron utilizadas por otras especies de guacamayas más pequeñas. La interferencia por competencia intraespecí fica de las guacamayas reproductivas podría excluir a reproductores potenciales de las cavidades, limitando así la disponibilidad de cavidades en áreas en donde los sitios de anidación se encuentran agrupados.

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 distance of 100–200 m between nest trees. In a given breeding season, active parrot nests were separated by a mean 950 ± 890 m. Parrot nests were also located significantly closer to a tree used as a nest in the previous breeding season than the distance between nearest nesting conspecifics. This pattern suggests that conspecifics influence the spatial distribution of reproductive pairs breeding simultaneously, with nesting pairs occupying areas where suitable cavities are more numerous. The behavioral spacing requirements of nesting parrots may limit breeding densities and restrict management strategies to increase numbers of nesting pairs within protected areas.

SEASONAL VARIATION IN ACTIVITY PATTERNS OF JUVENILE LILAC-CROWNED PARROTS IN TROPICAL DRY FOREST

Abstract We used radio-telemetry techniques to determine hourly activity patterns of 29 juvenile Lilac-crowned Parrots (Amazona finschi) during 1996–2000 in tropical dry forest of Jalisco, Mexico. Parrots had two peak activity periods—early morning and late afternoon—for both overall activity and local movement. Individuals were generally inactive and did not change location for 5–6 hr during the middle of the day. Parrots were more active in the dry season than in the rainy season, although movements resulting in a change of location did not vary between seasons. Seasonal variations in activity of Lilac-crowned Parrots may be related to variations in food availability or temperature. Activity patterns of parrots need to be considered when evaluating habitat use or survey data.

Postfledging Survival and Development of Juvenile Lilac-Crowned Parrots

Abstract We fitted radiotransmitters to 68 lilac-crowned parrot (Amazona finschi) fledglings from 1996 to 2003 to determine the survival and development of juveniles during their first year after leaving the nest. Overall, first-year survival was 73% (CI = 53–94%) and all mortalities occurred within 5 weeks of fledging, with highest mortality in the first week postfledging. Survival varied between years, influencing recruitment of independent young in the population. Nesting lilac-crowned parrots produced 0.70 independent young per egg-laying pair during 1996–2003. Lowest productivity of 0.25 independent young per pair occurred in 2003, with 40% postfledging survival. Juvenile development after fledging was characterized by variations in mobility, distance from the nest, and separation distance between siblings. Mobility and distance of young birds from the nest increased linearly with months postfledging. The first 2–3 weeks after fledging were characterized by low mobility and survival of young parrots, making this the most critical phase postfledging. The dependency period for young parrots extended to 4–5 months postfledging and was characterized by increased mobility and low separation between siblings, as juveniles traveled in family groups. Independence occurred in month 5 and was marked by a significant increase in mobility and separation between siblings, indicating the break-up of family groups. The first weeks after leaving the nest were crucial for survival and highlight the need for secure habitats where fledglings can improve flight and locomotory skills. The 4–5-month dependency of young parrots may be a key period for development, enhancing survival, and establishment in the breeding population. Release programs need to replicate learning and development acquired during the postfledging dependency phase to enhance survival of captive-reared psittacines. Researchers should conduct surveys of parrot group sizes during the dependency period 1–4 months after the end of nesting to provide reliable demographic data on annual recruitment of wild populations.

Reduced current distribution of Psittacidae on the Mexican Pacific coast: potential impacts of habitat loss and capture for trade

Ecological niche models provide useful predictions of species distributions, but may fail to detect reductions in distribution due to factors other than habitat loss, such as hunting or trade. From 2001 to 2009, we conducted field-surveys along the Mexican Pacific coast to obtain presence–absence data for nine Psittacidae species. We applied Genetic Algorithm for Rule set Prediction (GARP) ecological niche modeling, using field-survey presence data to determine the potential current distribution of each species, and incorporated absence data to delineate extirpation areas. All parrot species showed a reduced current distribution, ranging from 9.6 to 79% reduction of estimated original distribution. The threatened and endemic species of Amazonaoratrix, Amazonafinschi, and Forpuscyanopygius suffered the greatest distribution reduction, higher than previously estimated by habitat-based models, suggesting that capture for trade may have caused extirpation of these species. The greatest extent of current distribution was occupied by Aratingacanicularis, Amazonaalbifrons and Aramilitaris, which continue to occur throughout most of their original distribution. Amazonaauropalliata, Aratingastrenua, and Brotogerisjugularis also occur throughout their restricted distribution in coastal Chiapas, and show a relatively small distribution reduction, but had the highest proportion of modified lands within their current distributions. Our results highlighted the regions of coastal Guerrero, northern Nayarit, and southern Sinaloa where parrot species have been extirpated even though GARP models predicted suitable habitat available. Ideally distribution models should be verified in the field to determine conservation priorities, and efforts should be directed to maintain populations of species with greatest distribution reductions.

The Endangered yellow-headed parrot Amazona oratrix along the Pacific coast of Mexico

The yellow-headed parrot Amazona oratrix is categorized as Endangered on the IUCN Red List but little is known about its distribution, particularly along the Pacific coast of Mexico. We used ecological niche models, with presence records from museum collections and historical sightings, overlain on vegetation maps, to predict the historical range of the yellow-headed parrot along the Pacific coast of Mexico. We compared this with the current range of the species, estimated with ecological niche models using presence–absence data from surveys during 2003–2008. We estimate that the range of the yellow-headed parrot along Mexico’s Pacific coast has contracted by 79%. The current range may now cover only 18,957 km 2 , in three main areas. At one of these, a small isolated area on the coast of Jalisco, the species may be vulnerable to extirpation or genetic endogamy. There is a lack of conserved tropical semi-deciduous forest, which provides optimal habitat for reproduction of this parrot, within the current range of the species. Only the south, along the coast of Oaxaca, has extensive areas of this habitat. There are only three, small, protected areas within the species’ current range. Conservation strategies need to be implemented to restore connectivity between the three main areas of the current range of the yellow-headed parrot on the Pacific coast of Mexico.

Importance of the lilac-crowned parrot in pre-dispersal seed predation of Astronium graveolens in a Mexican tropical dry forest.

Parrots represent a large biomass of canopy granivores in tropical forests, and may be effective pre-dispersal seed predators. We evaluated the importance of the lilac-crowned parrot (Amazona finschi) as a pre-dispersal seed predator of Astronium graveolens (Anacardiaceae) in tropical dry forest. Seeds were collected in fruit-traps beneath 22 treestocomparepre-dispersalseedpredationbyparrotsandinsects,anddeterminewhetherintensityofseedpredation was related to fruit-crop size or the aggregation of fruiting conspecifics around focal trees. Ground-level exclosures wereestablishedtocomparepost-dispersalseedpredationbyvertebratesandinsects.Thelilac-crownedparrotpredated 43% of seeds pre-dispersal, while insects predated only 1.3%. Intensity of pre-dispersal seed predation by parrots was significantly greater in high-fruiting 0.79-ha resource patches, and was not related to fruit abundance of the focal tree. Foraging parrots also discarded immature fruits below the tree, causing a total 56% pre-dispersal loss of seed production,whichwasgreaterthanpost-dispersalremovalbyvertebrates,mainlyrodents(51%)orinsects(36%).Our results show that parrots play an important role as pre-dispersal seed predators in tropical dry forests. The reduction of parrot populations in tropical forests may have consequences for seed predation, affecting recruitment patterns of canopy trees.