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At least 271 records · Page 15Linked to original sources

PubMed1977

Effect of handling on maternal behavior following return of pups to the nest.

Handling rat pups during the 1st week after birth altered adult behavior in the open-field, whereas simply spearating the pups from their mothers during the same period produced differences in body weight at weaning. Observations of mother-infant interaction following pup treatment yielded different patterns of maternal behavior. Moreover, pups receiving early treatment were more active as adults in a novel environment and had a greater body weight at weaning. The quality of maternal care and the immediate effects of infantile stimulation on the mother-infant relation should be considered in specifying a mediating mechanism for the effects of early experience.

Age Factors↗

PubMed1977

Significance of the weaning period for natality and maternal behaviour of laboratory rats.

Normally weaned females (at 30 days) displayed seasonal cyclic changes in natality and the characteristics of the young. Natality in the spring and summer was high, the litters were large, the proportion of females and males in the litter was equal and deaths among the unweaned young were very few. Natality in the autumn and winter was low and the litters were small and consisted mainly of males. The death rate among the young was higher than in the spring and summer. Prematurely weaned females (at 15 days) displayed no seasonal cycle either in natality or in the characteristics of the young. The studied parameters corresponded to the values found in the spring and summer in normally weaned females. No differences were found in maternal retrieving, but there was a marked difference in nest-building. The normally weaned female tore up paper (building material) into small fragments 24 hours before giving birth and dropped the young into a soft nest of finely shredded paper. On leaving the nest it covered the young up. The prematurely weaned female scattered the paper about the cage 24 hours before giving birth and dropped the young into a depression stamped out among whole pieces of paper. It did not cover the young up on leaving the nest. The cause of the difference in building behaviour is evidently that prematurely weaned females failed to acquire early experience of this behaviour between the 15th and 30th day of life.

Animals↗

PubMed1997

Paternal care reduces maternal hyperthermia in Djungarian hamsters (Phodopus campbelli).

Throughout lactation, maternal body temperature, nest attendance, activity level and reproductive success of solitary female Djungarian hamsters housed at the recommended ambient temperature of 23 degrees C (Canadian Council on Animal Care guidelines) were compared with those of paired females housed at the same temperature and with solitary females housed at the natural burrow temperature of 18 degrees C. As expected, cooler ambient temperature improved pup survival and weaning weight. Likewise, paternal presence largely compensated for the poor pup growth typical at 23 degrees C. However, the mechanisms were not the same. Females at reduced ambient temperatures were as hyperthermic as females at the higher temperature and spent the same proportion of their day at very high body temperatures. However, the steeper temperature gradient available for passive cooling allowed those females to enhance maternal care by shortening their nest bout absences. In contrast, body temperatures of paired females were tightly regulated compared to the hyperthermia of solitary females and rarely included the highest body temperatures. This alleviation of maternal hyperthermia was not achieved through a reduction in nest attendance. Therefore, maternal hyperthermia in Djungarian hamsters is not essential and may be considered a substantial cost to females when males are not present.

Animals↗

PubMed1977

Nest and home.

A nest as a rather loose construction of plant material, as it is used by most birds and some of the lowest primates, never serves as a goal of flight, very rarely as a sleeping place but mainly as a support for the offspring. A home, however, as used by many nonprimate mammals and other vertebrates, is a solid construction or an excavation in a solid material (tree hole, burrow, etc.) which serves principally as a goal of flight in case of danger, also as a sleeping place and temporarily as a nest, that is a fix-point for raising the young. In the phylogeny of primates the nest has been given up very early. The sleeping nest of pongids has nothing to do with it. Whereas the most primitive primates using nests transport their young with the mouth, in all other primates the young has to grasp actively the mother's (parent's) hair to be tranported. When the hair disappeared phylogenetically, technical devices came into use.

Animals↗

PubMed1994

Investigating sea turtle migration using DNA markers.

The past year has seen a further marshaling of genetic evidence for 'natal homing' in several species of marine turtles, a phenomenon wherein females, upon reaching sexual maturity, exhibit a propensity to return to nest at or near the respective beaches upon which they hatched some two or more decades earlier. This genetics-based inference stems from the strong spatial patterning observed in mitochondrial DNA lineages among nesting sites. Rookery-specific mitochondrial DNA markers are now being employed to monitor the natal sources of individuals captured at other phases of the life cycle, and the genetic findings have important conservation ramifications.

Animals↗

PubMed2003

Changes in plasma corticosterone and adrenocortical response to stress during the breeding cycle in high altitude flycatchers.

Plasma corticosterone levels were monitored in a breeding population of Dusky Flycatchers (Empidonax oberholseri) at Tioga Pass, in the eastern Sierra Nevada. Seasonal changes in baseline plasma corticosterone levels were largely related to changes in reproductive status. Levels in both sexes were highest during the period preceding the female's initiation of a clutch. Females, alone, incubated, but males provided food regularly for their incubating mates. Excepting transient peaks in female corticosterone levels that immediately preceded ovipositions, steep declines in baseline levels of corticosterone in both sexes corresponded to the onset of parental attentiveness. Serial measurements of plasma corticosterone levels over a 1-h period of restraint, indicated that these declines originate at the level of the hypothalamo-pituitary-adrenal response system. Increases in stress-induced plasma corticosterone were significantly greater during the period preceding clutch initiation (prenesting) than during the nesting period (incubation and nestling periods). Despite the changes in corticosterone between prenesting and nesting periods, variability in corticosterone levels during both stages was negatively correlated with body condition (body mass and fat, corrected for size), and level of parental investment. Highest levels of plasma corticosterone were observed in lighter, leaner flycatchers, and during the hours when self-foraging activities were highest; lowest levels were seen in heavier, fatter birds, and those foraging for chicks. This relationship between corticosterone and parental care extended to a small number of accessory males that were acting as helpers at the nest. These results suggest that variation in the length of the reproductive cycle and degree of parental investment may help to explain the level of adaptive modulation of the adrenal stress response in species that breed in unpredictable environments.

Adaptation, Physiological↗

PubMed1975

Long term changes in nest condition and pup grouping following handling of rat litters.

Observation of rat litters over the entire preweaning period revealed long term changes to result from handling pups. Handled litters had fewer good nests and were less likely to be found in a single group than control litters. These differences are not attributable to the disturbances per se, as litters where the mother was removed did not differ significantly from undisturbed controls. The differences occurred predominantly in the daytime when maternal activity was at its lowest.

Animals↗

PubMed1975

The influence of the sex of litter-mates on subsequent maternal behaviour in Rattus norvegicus.

Female rats reared in unisexual (U) or bisexual (B) cross-fostered litters were mated at 75 days of age and their maternal behaviour compared by periodic observation over 20 days following birth of their litters. In two separate experiments, U-females showed a lower incidence of pregnancy and, at birth, of litters with ten or more pups than B-females (P less than 0-05). Litters culled to ten animals on the day after birth were significantly heavier in B- than in U-females, although this difference was not evident at weaning as litters reared by U-females showed a relatively greater (P less than 0-01) increase in weight during the investigation than the corresponding litters reared by B-females. Using a scoring method, no difference was evident in the opportunities that U- and B-females offered for their pups to suck, and, when not nursing pups in the nest, both groups of females engaged equally in activities such as grooming, sleeping, eating, and rearing on their hind legs. Throughout the 20-day observation period, B-females maintained significantly more elaborate nests (as scored on an arbitrary scale) than U-females. This difference was evident in females rearing litters of both five and ten animals, and was observed in two separate experiments. In addition, whereas only 15 per cent of U-females were observed nest-building, over 60 per cent of B-females were noted to be engaged in this activity on one or more occasions (P less than 0-001). It is suggested that, in the light of previous findings, these results may reflect differences in oestrogen and/or progesterone metabolism in unisexually-reared and bisexually-reared female rats.

Animals↗

PubMed2003

Gathering public information for habitat selection: prospecting birds cue on parental activity.

Because habitat quality strongly affects individual fitness, understanding individual habitat selection strategies is fundamental for most aspects of the evolution and conservation of species. Several studies suggest that individuals gather public information, i.e. information derived from the reproductive performance of conspecifics, to assess and select habitats. However, the behavioural mechanisms of information gathering, i.e. prospecting, are largely unknown, despite the fact that they directly constrain individual selection strategies. To test whether prospectors gather public information or other cues of habitat quality, we manipulated brood size of collared flycatchers (Ficedula albicollis) and investigated subsequent attraction of prospectors. Experimentally adding two nestlings increased the probability of attracting prospectors to the nest as a result of increased parental feeding rates. Prospectors were attracted to the most successful sites because feeding rate predicted subsequent fledgling production. In the year following prospecting, individuals selected a breeding site very close to the prospected site. These results provide the first experimental evidence, to our knowledge, of the links between information gathering behaviour and breeding habitat selection strategies based on public information.

Animals↗

PubMed2003

Phase shifts and Per gene expression in mouse suprachiasmatic nucleus.

In mammals, circadian rhythms controlled by the suprachiasmatic nuclei are entrained by photic stimuli. To investigate the molecular mechanism of photic entrainment, we examined light-induced behavioral phase delays and associated changes in mPer1 and mPer2 gene expression in the suprachiasmatic nuclei of two mouse lines artificially selected for nest-building behavior. Big nest-builders show larger phase delays than small nest-builders. Light-induced mPer1 and mPer2 expression was examined in individual mice previously tested for phase shifting at circadian time 16. Light-induced mPer2 expression was significantly higher in big compared to small nest-builders. No difference was found between lines in light-induced mPer1 expression. The results suggest a more important role for mPer2 than for mPer1 gene expression in behavioral phase delays.

Animals↗

PubMed2001

Endocrine regulation of periparturient behaviour in pigs.

Pigs begin behavioural preparations for birth about 1-2 days before parturition. Prepartum sows wander to select a suitable site and then construct a maternal nest. The signal that initiates this behavioural cascade probably results from fetal maturation but is unknown. However, endogenous PGF2 alpha appears to be involved early on in an endocrine pathway that projects to the brain and can generate most of the prepartum behavioural components. This period of intense activity is followed by a quiescent phase of lying in the nest for some hours before fetal ejection occurs. Feedback from a completed nest or abdominal discomfort may both contribute to the end of nest building. In the postpartum phase, sows have to deal with the apparently conflicting drives of remaining passive to reduce accidental or deliberate damage to piglets, while at the same time responding actively to their needs. In commercial environments, animals frequently fail in this task. Although environmental influences on piglet survival have received much experimental attention, the genetic, social and endocrine drives that control sow behaviour after parturition remain poorly understood and their clarification is a major challenge for the future.

Animals↗

PubMed1993

Circadian rhythms differ between selected mouse lines: a model to study the role of vasopressin neurons in the suprachiasmatic nuclei.

Mice selected for differences in nest-building behavior differ in the number of arginine-vasopressin (AVP)-immunoreactive neurons in the suprachiasmatic nuclei (SCN). Although previous efforts to link AVP-immunoreactive neurons in the SCN to clock function have failed, we show that differences in several circadian parameters are associated with differences in the number of AVP-immunoreactive neurons between the selected lines. Although an alternative interpretation is discussed, we hypothesize that these neurons may relay timing information from the circadian pacemaker in the SCN for wheel-running activity. In addition, phase-response curves (PRCs) to 15-min light pulses in constant darkness also differ between the selected lines. However, these differences are not associated with the number of the AVP-immunoreactive neurons in the SCN, but are associated with the level of nest-building behavior. Compared to the Brattleboro rat, in which homozygous rats are deficient for AVP in the entire brain, our system, exhibiting a wide range of variability, has more specific utility for studying the role of the output pathways of the SCN in circadian rhythm control.

Analysis of Variance↗

PubMed2003

Sympatry and allopatry in two desert ant sister species: how do Cataglyphis bicolor and C. savignyi coexist?

Two extremely morphologically similar sister species of desert ants, Cataglyphis bicolor and C. savignyi, exhibit broadly overlapping distributional ranges within Tunisia. In order to analyse the microhabitats of C. bicolor and C. savignyi within the sympatric and allopatric areas of both ant species, the plant species located at 113 different nest sites of the two ant species were determined. In the sympatric area, the two species exhibit a clear-cut nest site segregation. This is not the case in the allopatric areas. Hence the two species differentiate their microhabitat only when they are sympatric. The plant species associated mainly with the nest sites of C. bicolor indicate that this species prefers a type of vegetation that needs irrigation. This is in contrast to the nest sites of C. savignyi, which are usually found around plants that characterize typical dry steppe areas. As the ants' foraging paths recorded in the sympatric area reveal, C. bicolor performs significantly shorter foraging runs with respect to both length and time, and covers a much smaller foraging range than C. savignyi does. This result reflects the fact that the microhabitat occupied by the colonies of C. bicolor is richer in food abundance. When direct interspecific interactions were investigated by placing a bait midway between two heterospecific nests, C. bicolor foragers dominated over those of C. savignyi. The same dominance of C. bicolor over C. savignyi occurred in laboratory experiments. These results suggest that the dominant species drives the subordinate one out of the high quality microhabitats, and that the subordinate species is forced to survive in the less lucrative habitats. In conclusion, coexistence seems to be maintained by the asymmetric competitive relationship between the two species and the fact that the subordinate species has the ability to endure in the less favourable microhabitat.

Animals↗

PubMed1990

Defensive burying, nest relocation, and pup transport in lactating female rats.

A wire-wrapped wooden dowel was inserted through the wall of the nest compartment of a two-compartment box. There were four conditions. Some lactating female rats were shocked by the dowel when they first touched it, and some were not, after which the dowel was either immediately withdrawn from the chamber or left in place for the duration of the ensuing 30-min test period. Three defensive behaviours were observed during the tests: the mothers buried the shock source with bedding from the floor of the chamber, they transported their pups to the adjoining "safe" chamber, and they built a new nest in the safe chamber from material salvaged from their original nest. The shocked mothers that were confronted with the shock source throughout the test period displayed significantly more of each of these three defensive behaviours than did the mothers in the other three conditions. The methods used in this study provide a simple, reliable, safe paradigm for studying maternal defensive behaviour; the results indicate that the defensive capacities of the rat extend far beyond stereotypical flight, freeze, and fight responses, which have been the focus of most research on rodent defense.

Animals↗

PubMed2002

Male-only care and classical polyandry in birds: phylogeny, ecology and sex differences in remating opportunities.

It has been argued recently that the combination of male-only parental care and classical polyandry in birds is the most interesting and yet the least understood of all avian breeding systems. Despite a huge number of hypotheses, careful comparative analyses have repeatedly failed to identify consistent ecological differences between species showing male-only care and closely related species showing other patterns of care. This has led to the suggestion that such analyses fail because the crucial differences are between ancient lineages rather than between closely related species. Here, therefore, I use comparisons between families to test three well-known hypotheses: that male-only care is associated with: (i) a low rate of fecundity; (ii) large egg size relative to female size; or (iii) female-biased opportunities for remating. Families showing male-only care do not differ from families showing female-only care with respect to rate of fecundity or relative egg size. There is, however, a significant difference between these two groups of families with respect to an index of remating opportunities, nesting density. Families showing female-only care nest at high density, while those showing male-only care nest at very low density. This is one of the first times a consistent ecological correlate has been identified for male-only care in birds. It suggests that female-only care arises (or persists) in families where remating opportunities are abundant for both sexes, whereas male-only care arises (or persists) in families where remating opportunities are rare for both sexes and particularly scarce for males. This in turn suggests that sex differences in remating opportunities are the key ecological factor in determining male-only care and classical polyandry in birds.

Animals↗

PubMed1975

Population control in confined colonies of golden hamsters (Mesocricetus auratus Waterhouse).

The mechanisms by which confined colonies of Golden Hamsters regulate the density of their population were investigated. Six experimental populations were established with two males and two females each and allowed to grow freely for 3-8 months. At no time did any population exceed eight individuals. This appeared to be the result of a high rate of infant mortality due to failure of pregnant and parturient females to isolate themselves from the others. Two other populations were then established allowing many more nesting areas and more room for dispersal, but animals continued to crowd together and infant survival did not improve. These results contrast sharply with the large ultimate populations and only slowly developing disturbances seen in rats and mice. This difference in population control appears to be the direct result of a species difference in the tolerance of adults for strange newborns. In two further short-term experiments, the effects of the number and sex of adults in the founding population were systematically examined. The critical density at which no pups survived past the first day was six or more animals; females appeared to contribute more than males to infant mortality.

Animals↗

PubMed1982

Plasma concentrations of prolactin during incubation and parental feeding throughout repeated breeding cycles in canaries (Serinus canarius).

Concentrations of prolactin were measured in the plasma of male and female canaries serially sampled during repeated breeding cycles. Concentrations in female canaries were low during nest building and increased significantly (P less than 0.05) during the first few days of incubation. Levels increased further (P less than 0.01) in the middle of the incubation period to reach concentrations which were ten times higher than before breeding. Levels remained high for several days after the eggs hatched, as the young were fed in the nest. Prolactin concentrations declined gradually as the young were reared, reaching basal levels by the time the young were fledged, but always increased again in the females as they began incubating eggs in subsequent breeding cycles. Male canaries, which do not incubate but do assist in feeding the young, showed only slight increases in prolactin during the parental period. Male and female canaries which did not breed had low levels of prolactin throughout the experiment. The results show that prolactin secretion is high not only during incubation but also during the parental feeding phase in an altricial passerine bird. These findings are discussed in relation to the different patterns of prolactin secretion which occur during breeding in other birds.

Animals↗

PubMed1975

Adaptive significance of synchronized breeding in a colonial bird: a new hypothesis.

Bank swallows nest gregariously in colonies usually ranging from 10 to 300 nests. Different pairs within the same colony are highly synchronized with each other, and 67 percent of the nests fledged their young over a period of only 6 days. This high degree of synchronization is demonstrated to be of adaptive significance. Reproductive fitness increases as a function of the precision of synchrony of the colony. It is proposed that social foraging plays an important role in maximizing the feeding efficiency in this species and that asynchronous breeding decreases the effectiveness of this social foraging, particularly in late nesters and among young, newly fledged birds. An individual that fledges either early or at the peak of synchrony will emerge to find a steady stream of other bird traveling to local, ephemeral, concentrations of food. The late emerger finds itself practically alone and thus is deprived of the potential benefits of the pooled information about locations of food resources available to the full colony.

Adaptation, Biological↗