Natural cavity restoration as an alternative to nest box supplementation

Nest box supplementation is widely used to increase nest‐site availability for cavity nesting animals but the analysis of its effects on individuals breeding in natural cavities is often neglected. This study offers a novel restoration technique to revert abandonment of natural breeding sites by a secondary cavity avian bird, the European roller (Coracias garrulus), and other ecologically similar species. We found that, after a program of nest box supplementation with ensuing monitoring, rollers gradually abandon nesting in natural and seminatural cavities in favor of nest boxes because the latter are of higher quality. We examine whether reducing the entrance size of natural and seminatural cavities improves their suitability for rollers. A 6‐year program reduced the diameter of the entrance of sandstone cavities and cavities in bridges. This led to a high occupancy (59%) of manipulated nest‐sites. Manipulated sites were most frequently occupied by rollers and little owls (Athene noctua) (31 and 18% of sites, respectively). Manipulation did not affect clutch size or fledgling success. We suggest that nest‐site diversity and nesting in natural cavities should be preserved to reduce nest box dependence. Our study illustrates the value of nest boxes when used alongside restoration of natural breeding sites and provides insights for the management of natural cavities.     

The assessment of fear in domestic hens exposed to a looming human stimulus

The behavioural and physiological responses of hens exposed to a slowly approaching human being were assessed using remote observation and radio telemetry of heart rate. Forty isolated hens of two strains and from two rearing environments were used. The sequence of behavioural changes included looking around, ceasing feeding, head shaking or complete withdrawal and finally crouching or escape behaviour. The heart rate rose from a mean level of 303 beats/min when the birds were at rest, to 465 beats/min when the cage was opened and the bird caught and held at the conclusion of the approach. The light hybrid strain showed more pronounced behavioural responses and a greater proportional rise in heart rate in the course of the approach than the medium hybrid birds, consistent with the induction of a higher level of fear. An environmental effect was also observed, pen-reared birds were more disturbed than caged ones. The similarity of the time course of the physiological and behavioural measures supports the concept of fear as an intervening variable which has simultaneous effects on heart rate and behaviour. Both may be effective in assessing fear, and they should be regarded as complementary rather than alternative measures.     

Eggs fertilizability in domestic hens Gallus gallus domesticus as a function of the yolk surface area

The increase of egg mass and reliable decrease of egg fertilizability were observed when the mass surface area of yolk (egg) increased. The results obtained suggest that, in addition to the number of viable spermatozoa penetrating across the perivitelline membrane within 15-20 min after ovulation, the probability of fertilization depends on the area of egg surface, which approximately corresponds to the area of perivitelline membrane. Apparently, the ratio of receptors' numbers and spermatozoa, which contact with them on the germ disc surface, to their number on the rest part of perivitelline membrane decreases with the increase of yolk size. The decreased egg fertilizability concomitant with the increased area of perivitelline membrane suggests that the egg size is one of the factors of fertility of the female gametes as concerns both variability of the egg composition and age.     

Social preferences of domestic hens for domestic vs. red junglefowl males and females

The striking dimorphism of male and female junglefowl may have evolved in large part due to female choice of mates. However, domestic fowl hens consistently chose domestic, not junglefowl, males as well as females in preference tests. Either genetic predisposition to favor junglefowl morphological features over those of the domestic types utilized in these tests was overridden by experience or such genetic predisposition does not exist in the breed we tested.     

The nest as a factor determining clutch-size in tropical birds

Summary Discussions of the evolution of clutch-size in birds have largely ignored the physical characteristics of nests. In the tropics, the size and structure of nests have evolved under the influence of intense predation by nest-predators. One result of selection for inconspicuousness has been a reduction in nest size, in some cases to an extreme degree. It is argued that reduction in nest size has been an important factor limiting clutch-size, and, more generally, that the evolution of clutch-size cannot be fully understood without considering the dimensions and other physical properties of nests.

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Das Nest als Faktor für die Determination der Gelegegröße bei tropischen Vögeln

Zusammenfassung In Diskussionen über die Evolution der Gelegegröße wurden die durch das Nest gegebenen Bedingungen bisher weitgehend vernachlässigt. In den Tropen haben sich Struktur und Größe des Nestes unter dem Druck von Nesträubern entwickelt. Ein Ergebnis der Selektion in Richtung auf Unauffälligkeit ist die Reduktion der Nestgröße, in einigen Fällen sogar bis auf ein extremes Maß. Es wird betont, daß die Verringerung der Nestgröße ein wichtiger Faktor für die Begrenzung der Gelegegröße darstellte und daß ganz allgemein die Evolution der Gelegegröße nicht ohne die Berücksichtigung der Ausmaße und anderer physikalischer Eigenschaften des Nestes verstanden werden kann.

     

Social learning influences the preferences of domestic hens for novel food

It has been argued that social learning helps animals either avoid noxious substances or identify food items, but evidence suggests that avian social learning is fundamentally different from that of mammals. In two experiments, we investigated whether the preferences of domestic hens, Gallus g. domesticus, for novel food were influenced by observing the feeding behaviour of conspecifics. In experiment 1, we attempted to confirm that birds can develop socially learnt aversions to unpalatable foods. Despite demonstrators showing a highly visible ‘disgust reaction’ after eating unpalatable coloured food, observers did not develop aversions to similarly coloured food. In experiment 2, we aimed to determine whether preferences for palatable food were socially learnt, and whether the extent of a demonstrator's preference for novel food affected the magnitude of the observer's socially learned preference. Demonstrators ate coloured food of standard or high palatability, or did not peck food at all. When the demonstrators pecked more frequently or fed more quickly from the food, the observers consumed a greater proportion of food of the same colour; however, this was only when the food was red, not green. We argue this indicates an unlearned aversion to red food, overcome by social learning of the food being highly palatable. The results provide no evidence that adult hens learn aversions through observing disgust reactions, but show that hens are sensitive to the extent of demonstrator preferences for palatable food. The data do not support the hypothesis that avian social learning is fundamentally different from that of mammals. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

The effect of light on the choice of nests by domestic hens

The involvement of light in nest-site selection by domestic fowls was tested in two strains of laying hens at two stages of maturity. Individuals that were about to lay an egg were isolated in a pen and given a choice of two sorts of nest-box, one illuminated internally and the other without illumination. Nearly all birds tested laid in one of the boxes provided, but their choice of dark or light conditions varied strongly with both strain and maturity. Only one of the four categories of hen, those of a White Leghorn strain laying their first egg, exhibited the expected preference for dark nests. Birds of a strain derived from Rhode Island Reds were more likely to lay in light nests, and with both strains hens which had previously been laying in open pens showed greater preference for light nests than did naïve individuals. These results suggest that light intensity is not a fundamental factor influencing nest-site selection, but it may nevertheless haveto be considered in the management of laying hens.     

Note on a method for individual recognition in feed pecking in free running groups of hens

A system for automatic registration and individual recognition of feed pecking (activity and quantity) in groups of free running hens was tested. A PIT (Passive Integrated Transponder)-tag system was used to separate and register individuals when they were feeding. An electronic balance system placed under the feeder registered the amount eaten by each individual on a PC. A test with two different feed stuffs; oat and wheat was performed on three hens during a total of 6 weeks.     

Influence of nest seclusion and nesting material on pre-laying behaviour of laying hens

Provision of nest sites is beneficial for the welfare of laying hens in intensive production systems. The design of these nest sites has a direct effect on pre-laying behaviour. The aim of this study was to investigate the effects of screening off the entrances of the nest boxes with non-transparent flaps and providing nesting or flooring material on pre-laying behaviour. Eighteen individual Hisex brown laying hens and 18 groups of five hens were tested for 2 days in a test cage containing three nest boxes each with a different nesting material (peat, artificial turf and plastic-coated wire mesh). On one of the days the nest boxes were equipped with plastic flaps at the entrances. Pre-laying behaviour was analysed using focal sampling. Both degree of seclusion and nesting material had an effect on pre-laying behaviour of hens. Nest boxes with flaps were visited less frequently but for a longer duration per visit than nest boxes without flaps. Hens spent more time sitting and scratching, and less time standing and moving when flaps were present. Hens also received fewer pecks (group test) when nest boxes were equipped with flaps. Major differences were found between pre-laying behaviour on coated wire mesh compared to peat and artificial turf with shorter duration of nest visits (group test), more standing (group test) and moving (individual and group test), and less sitting (individual and group test) and object pecking (group test) on coated wire mesh. Differences in pre-laying behaviour on peat versus artificial turf were observed for the behaviours moving (less on peat), sitting (more on peat in the individual test) and object pecking (more on peat in the group test).

It is concluded that hens show more settled pre-laying behaviour and more nest-building behaviour in the presence of flaps at the entrances of nest boxes. These results indicate that seclusion of nest boxes with non-transparent flaps is beneficial to laying hen welfare. Differences in pre-laying behaviour also suggest that plastic-coated wire mesh is less suitable as nesting material than peat and artificial turf.     

Early rearing enrichments influenced nest use and egg quality in free-range laying hens

In Australia, free-range egg production pullets are typically reared indoors, but adult layers get outdoor access. This new environment may be challenging to adapt to, which could impair egg production and/or egg quality. Adaptation might be enhanced through rearing enrichments. We reared 1386 Hy-Line Brown® chicks indoors with three treatments across 16 weeks: (1) a control group with standard litter housing conditions, (2) a novelty group providing novel objects that changed weekly, and (3) a structural enrichment group with custom-designed structures to partially impair visibility across the pen and allow for vertical movement. Pullets were transferred to a free-range system at 16 weeks of age with daily outdoor access provided from 25 until 64 weeks. Daily egg production at different laying locations (large nests, small nests and floor), weekly egg weights and egg abnormalities were recorded from 18 to 64 weeks old. External and internal egg quality parameters of egg weight, shell reflectivity, albumen height, haugh unit, yolk colour score, shell weight and shell thickness were measured at 44, 52, 60 and 64 weeks. There was a significant interaction between rearing treatment and nest box use on hen-day production from weeks 18 to 25 (P < 0.0001) with the novelty hens laying the most eggs and the control hens the fewest eggs in the nest box. Similarly, from 26 to 64 weeks, the novelty hens laid more eggs in the large nest boxes and fewer eggs on the floor than both the structural and control hens (P < 0.0001). Egg weight and abnormalities increased with age (P < 0.0001), but rearing treatment had no effect on either measure (both P ≥ 0.19). Rearing treatment affected shell reflectivity and yolk colour with the control hens showing paler colours across time relative to the changes observed in the eggs from enriched hens. The novelty hens may have established nest box laying patterns as they were more accustomed to exploring new environments. The differences in egg quality could be related to stress adaptability or ranging behaviour. This study shows that enriching environments during rearing can have some impacts on production parameters in free-range hens.     

A method for rating the individual distinctiveness of domestic cats

Fourteen adult female domestic cats were watched by two observers for 3 months. Ratings of 18 aspects of each cat's behavioural style were obtained independently from each observer. Correlations between observers were statistically significant for 15 of the 18 aspects and seven of the correlation coefficients were greater than 0·7. The ratings were compared with results of direct recording methods, where equivalent measures were available and, in five out of six cases, the results of the ratings and direct methods were significantly correlated. The rating method is, therefore, generally reliable and can be adequately validated. Some assessments of observer ratings which are not obviously and easily related to direct recordings may prove particularly useful in developmental studies of alternative modes of behaviour and the origins of individual differences.