'Do I know you?' Categorizing individuals on the basis of familiarity in kea (Nestor notabilis)

Categorizing individuals on the basis of familiarity is an adaptive way of dealing with the complexity of the social environment. It requires the use of conceptual familiarity and is considered higher order learning. Although, it is common among many species, ecological need might require and facilitate individual differentiation among heterospecifics. This may be true for laboratory populations just as much as for domesticated species and those that live in urban contexts. However, with the exception of a few studies, populations of laboratory animals have generally been given less attention. The study at hand, therefore, addressed the question whether a laboratory population of kea parrots (Nestor notabilis) were able to apply the concept of familiarity to differentiate between human faces in a two-choice discrimination task on the touchscreen. The results illustrated that the laboratory population of kea were indeed able to differentiate between familiar and unfamiliar human faces in a two-choice discrimination task. The results provide novel empirical evidence on abstract categorization capacities in parrots while at the same time providing further evidence of representational insight in kea.

Semen Collection and Spermatozoa Characteristics in the Kea Parrot (Nestor notabilis)

We describe the seminal characteristics of the kea parrot (Nestor notabilis), an endangered species endemic to the South Island of New Zealand. Semen was collected in the full breeding season from 6 birds in the collection of an amateur aviculturist. The manual massage technique was used. A total of 25 ejaculates was collected and evaluated for volume, degree of contamination, and spermatozoa concentration; motility and kinetic parameters were assessed on diluted samples (modified Tyrode's Albumin Lactate Pyruvate, pH 8.2, temperature 37.5°C) with a computer-aided sperm analyzer. Four ejaculates were not analyzed because of an excessively high degree of contamination. Semen color ranged from transparent or turbid yellow to whitish. The geometric mean of spermatozoa number/ejaculate was 765.9 ± 2084.7 × 10⁶. Total and progressive motility were 71.7% ± 20.0% and 59.8% ± 22.0%, respectively. Great variability was observed both among birds and among different ejaculates of the same subject. The seminal characteristics of kea are worth further investigation, with the aim of relating semen quality to fertility and defining a minimum inseminating dose for breeding purposes. A deeper knowledge of male reproductive biology also can increase the success of breeding programs and enable the use of the kea as a model species for other more threatened species, such as the kaka ( Nestor meridionalis ) and the kakapo (Strigops habroptila).

Chronic West Nile virus infection in kea (Nestor notabilis)

Six kea (Nestor notabilis) in human care, naturally infected with West Nile virus (WNV) lineage 2 in Vienna, Austria, in 2008, developed mild to fatal neurological signs. WNV RNA persisted and the virus evolved in the birds' brains, as demonstrated by (phylo)genetic analyses of the complete viral genomes detected in kea euthanized between 2009 and 2014. WNV antibodies persisted in the birds, too. Chronic WNV infection in the brain might contribute to the circulation of the virus through oral transmission to predatory birds.

The advantage of objects over images in discrimination and reversal learning by kea, Nestor notabilis

Studies investigating the same paradigm but employing different methods are often directly compared in the literature. One such paradigm used to assess behavioural flexibility in animals is reversal learning. Commonly, these studies require individuals to learn the reward contingency of either solid objects presented on the ground or images presented on a touchscreen. Once learned, these contingencies are swapped. Researchers often refer to trials required to reach learning criteria from different studies, to compare the flexibility of different species, but rarely take methodological differences into account. A direct evaluation of the validity of such comparisons is lacking. To address this latent question, we confronted kea, an alpine parrot species of New Zealand and known for its behavioural flexibility, with a standard reversal learning paradigm on the touchscreen and a standard reversal learning paradigm with solid objects. The kea required significantly more trials to reach criterion in the acquisition and the reversal on the touchscreen. Also, the absolute increase in the number of trials required for the reversal was significantly greater on the touchscreen. This indicates that it is not valid to compare learning speed across studies that do not correspond in the addressed methodology. Taking into account the kea's ecology and explorative nature we discuss stimulus abstraction (limited depth cues and tactile stimulus feedback) and the spatial relation between reward and stimulus on the touchscreen as possible causes for decreased inhibition in this condition. Contrary to the absolute increase in number of trials required for the reversal, the increase in relation to the acquisition was greater with solid objects. This highlights the need for further research on the mechanisms involved causing methodology-dependent differences, some of which we discuss, in order to increase the validity of interpretations across studies and in respect to the subject's ecology.

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We provide a first direct comparison of two standard reversal learning approaches.

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Discrimination and reversal of solid objects seems easier than on the touchscreen.

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This highlights issues when comparing the same paradigm using different approaches.