Charles J. Amlaner

A Synthesis of Sleep in Wild Birds

In this synthesis we have attempted to survey and reanalyse the current literature concerning bird sleep. This was achieved by first reviewing present theory describing functions of sleep. Two general models surfaced which encompass many of the specific sleep theories, namely homeostatic and ecological theories. The terminology used to describe sleep and other associated behaviour was organized into an operational hierarchy. We defined loafing behaviour as a general state of immobility. This functional heterogenous group may include comfort behaviour, feeding, social interaction, wariness, staring down and inactive behaviour. Sleep and associated behaviour are considered inactive behaviour. We next described the common sleeping postures as follows: 1. Bill on back or under scapulars; the classical sleep posture. 2. Bill forward or rest-sleep posture. 3. Head on ground. Specific sleep characteristics were also identified as: 1. Quality of sleep based on duration and frequency of eyelid closure. 2. Length of sleep, called sleep session time which is based on the summation of sleep bouts. A sleep bout is defined as the time elapsed during eye closure and opening. 3. Temporal patterning of sleep sessions which are suggested to be dependent on timing of other higher priority behaviours. 4. The resilience (flexibility) of sleep session time. An original analysis was conducted on these sleep characteristics and other environmental, constitutional, behavioural and predation factors. The results indicated that birds experiencing longer daylength slept less each day. Further, birds slept less if (1) overall dangers were greater and (2) they were more communal sleepers. Longer sleep session times were associated with greater exposure while sleeping (i.e. on a lake or mud flat). Several possible functions of sleep were then suggested. Protection theories encompass choice of a safe sleep site while addressing the significance of communal roosting. Recuperation theories were not adequately supported by quantitative studies. Energy conservation theories imply that birds sleep when doing other behaviour might be non-productive. We suggest a model based on eyelid blinking which allows for a degree of vigilance during sleep but which is also compatible with minimizing energy expenditure.

A Practical Guide to Radio Tracking

Abstract The art of practical radio tracking has more to it than the would-be tracker might anticipate. We try to provide some practical guidance in the choice and construction of equipment, in its use and its shortcomings.

Sleep in the Herring Gull (Larus argentatus)

Abstract Sleep postures and eye state of free-ranging herring gulls ( Larus argentatus ) were studied during the breeding season. Three mutually exclusive behaviours were observed, namely sleep, rest-sleep and rest postures. Arousal thresholds, eye blink rates and eye closure time were obtained during these behaviours. Significant relationships existed between eye blinking, eye closure, and a raised threshold of arousal when birds were in the sleep and rest-sleep postures. During a natural disturbance, birds in the sleep posture remained in this posture but did not blink their eyes: this is called pseudo sleep. Male gulls also exhibited a lower threshold of arousal while in the sleep posture compared with females. We conclude that rhythmic eye blinking is a good indication of sleep in herring gulls.

Changing Heart Rates of Herring Gulls when Approached by Humans

Abstract Herring gulls (Larus argentatus) respond to an approaching human by an ‘emotional’ tachycardia. This response, which did not habituate, had a form dependent on the distance between the gull and an approaching human. It could also be modified by changing the speed of approach. Because there are reasons for believing this to be of adaptive significance, it is suggested that the response can be used in the study of animal behavior.

Voltage-Controlled Oscillators: Inexpensive Alternative to Analog-to-Digital Converters

We describe a simple software mimic of an analog-to-digital (A/D) converter that is suitable for most laboratory applications requiring A/D. The routine samples output from a voltage-controlled oscillator that can be built for around

Design of a Remotely Controlled 'Locomotory' Platform Useful in Ethological Studies.

6. Results of proving trials show the output to be linear and sampling rates of up to 50/sec are possible.

A Handbook on Biotelemetry and Radio Tracking

A platform capable of movement from one point to another under remote control has been designed for use in behavior studies. Electrical and mechanical design criterion for the platform are discussed, and schematics and engineering drawings are included. The primary application was to study communication between Glaucous-winged gulls. Other applications for the platform (as in predator-prey studies and dispersal of birds from aerodromes) are suggested.