Abstract:
To claim and understand the uniqueness of any physical, chemical, or biological
system, it is necessary to use the same set of approaches, tools, and analyses to probe
other systems. Accordingly, to assess whether and how people are unique in their
perceptual, cognitive, and behavioural skills and algorithms when making decisions, a
parallel set of studies is required to examine how human and non-human animals
would respond. This thesis provides a structured experimental analysis of each of the
recognition system’s components; perception, cognition, and response; in the context
of avian brood parasitism. The study species are several potential hosts of brood
parasitic birds but an explicit aim of this work to provide a reference for future studies
on how to probe the perceptual, cognitive, and response traits in non-verbal
experimental paradigms, including non-hosts and working with people.
Hosts of avian brood parasites represent a powerful experimental system in which to
study well defined and evolutionarily relevant behavioural decision: brood parasitic
birds lay their eggs in other nests and the costs of parental care and reduced
reproductive success are borne by the hosts. Hosts, in turn, may reject costly
parasitism by ejecting foreign progeny or deserting parasitized nests. The cues used
by hosts to perceive, recognize, discriminate, and respond to foreign eggs have been
well studied in a variety of avian host-parasite systems. How, in turn, the hosts’
sensory and cognitive processes receive, sort through, and determine the behavioural
responses to these cues, remains mostly unclear.
The main chapters of the thesis set out to describe the results of two unpublished
studies on hosts’ recognition systems. The first study uses artificial colour
manipulation of hosts’ own eggs to determine whether specific colours are perceived
similarly to trigger rejection behaviours, irrespective of the presence of hosts’ own
eggs in the nest. The results suggest that foreign egg colours are perceived similarly
and rejection is triggered through comparisons with internal filters, or recognition
templates, even when hosts’ own eggs are not present. The second study also uses
artificial colour manipulation to assess the hosts’ specific behaviours to foreign eggs
and reveals that relative patterns of egg ejection and nest desertion are indicative of
hosts’ responses to foreign eggs.
These results provide detailed new information for our understanding of parasitic
birds’ impacts on hosts’ perceptual processes. It is also the aim of this thesis that these
studies may also be used as starting points towards a sample set of methodological
and analytical tools to determine whether and how other species, including people,
may use similar perceptual, cognitive, and behavioural decision rules to detect foreign
items in odd-egg-out paradigms.
