|
|
Hanggi, E. B., & Ingersoll, J. F. (2012). Lateral vision in horses: A behavioral investigation. Behav. Process., 91(1), 70–76.
Abstract: This study investigated lateral vision in horses (Equus caballus) for the first time from a behavioral point of view. Three horses were tested using a novel experimental design to determine the range of their lateral and caudolateral vision with respect to stimulus detection and discrimination. Real-life stimuli were presented along a curvilinear wall in one of four different positions (A, B, C, D) and one of two height locations (Top, Bottom) on both sides of the horse. To test for stimulus detection, the correct stimulus was paired against a control; for stimulus discrimination, the correct stimulus was paired against another object. To indicate that the correct stimulus was detected or discriminated, the horses pushed one of two paddles. All horses scored significantly above chance on stimulus detection trials regardless of stimulus position or location. They also accurately discriminated between stimuli when objects appeared in positions A, B, and C for the top or bottom locations; however, they failed to discriminate these stimuli at position D. This study supports physiological descriptions of the equine eye and provides new behavioral data showing that horses can detect the appearance of objects within an almost fully encompassing circle and are able to identify objects within most but not all of their panoramic field of view.
|
|
|
|
Komárková, M., & Bartošová, J. (2012). Lateralized suckling in domestic horse foals (Equus caballus). In K. Krueger (Ed.), Proceedings of the 2. International Equine Science Meeting (Vol. in press). Wald: Xenophon Publishing.
Abstract: Animals with eyes placed laterally on their head would respond differently to stimuli detected on their different sides. Visual cues from the left eye are processed in the right hemisphere which controls the intensive emotion expression and fast response to the stimuli, while the left hemisphere receiving the information from the contralateral eye is responsible for the routine behaviour and concentration. Different use of left/right eye for exploring environment and evaluation of different stimuli was recently described in domestic horses. They use left eye predominantly for watching novel object or frightening stimulus which indicates specialization of right hemisphere (RH) for appraisal of these types of stimuli. We presumed such lateralisation also in foals during suckling when only monocular vision can be employed for observing surroundings (foals suck mostly in antiparallel body position). Two mutually exclusive hypotheses about the origin of probable foal’s preference for particular suckling side were postulated: 1) visual lateralization, then the foals should suck more often from the mother’s right side (‘from right’), so as potential danger would be detected by the better adapted right hemisphere (i.e. left eye); 2) motor lateralization (the analogous concept as human “handness”), then a foal should suck predominantly from one side, either left or right, more often. Within two seasons, suckling behaviour of 59 Kladruby mares giving birth to 79 foals was observed from deliveries to abrupt weaning (4-7 months of age). From 10 607 recorded suckling solicitations, 50.2% were performed from right, thus there was no preference of the suckling side on a population level. However, we found large variability in the probability of suckling from right among individual foals (p<0.0001); the probability ranged from 0.22-0.98. One third of the foals (35.4%) showed strong, either right (N=13) or left (N=15) side preference which further strengthened with age (interaction suckling side preference*foal’s age: p<0.0001). Other tested variables, i.e. sex of the foal, age of the mother and identity of the herd were not significant. The probability that the mother rejected foal’s suckling solicitation (N=108) did not differ according to the suckling side (right/left) or suckling side preference (right/left/no preference). Suckling bout duration was not significantly influenced neither by the suckling side nor suckling side preference regardless the mother or the foal terminated the suckling bout. In conclusion, only 16 % of the foals revealed significant right side preference for suckling while 19 % left side and 65 % no preference. Thus, we can reject the visual hypothesis because a general trait to suck with left eye open for better danger detection and recognition is unlikely to occur, at least in up to 7 months old foals. Such a young foal is probably fully focused on suckling and relies on mother’s vigilance. Observed individual side preferences indicated more likely a kind of motor lateralization in part of the foals. Further research is needed to clear up the effects of age and individual experience of the foal. Supported by AWIN, EU FP7 project No. 266213.
|
|
|
|
Bouskila, A., de Vries, H., Hermans, Z. M., & van Dierendonck, M. (2012). Leadership roles in movements of free-roaming Konik horses (Equus caballus) in a Dutch reserve. In K. Krueger, & (Ed.), Proceedings of the 2. International Equine Science Meeting (Vol. in press). Wald: Xenophon Publishing.
Abstract: We observed the activity and movements of Konik horses (Equus caballus) in order to determine the initiators of movements and the individuals taking the lead in movements of the main groups. We conducted our observations between March-June 2010 along the shores of the Rhine river, in the Blauwe Kamer reserve, in the Netherlands. The horses were introduced to the reserve alongside with cattle to prevent the growth of the forest and maintain the grass habitat. We videotaped all observations on two digital video cameras, one providing the general view of the group and the other scanning and focusing on the individuals, to aid with identification. Horses were recognized based on individual profiles that were created for each one, consisting of photos of both sides and notes of the main characters, such as orientation and coloration of the mane, prominent scars and markings, etc. Twenty three horses (not counting foals) were organized in two harem groups with 11 individuals (two of which were dominant stallions) in the large group and six individuals (one of which was a stallion) in the second group. These two main groups were always within sight of each other, and two bachelor males moved usually in their vicinity. An additional group of three young bachelor males roamed elsewhere in the reserve. We divided the movements of the horses to local movements while grazing and to long-distance movements, in which the horses moved to a different grazing location, to a pond of water, resting area or groups of trees that were used by the horses for scratching themselves. During the local movements, any two of the three oldest females in the large harem group were enough to cause the whole group to follow them and gradually change position within the pasture. The smaller harem always followed the large harem’s movements. The long-distance movements of the large harem were sometimes initiated by one of the harem stallions that herded their group and at other times – by the oldest females. Soon after the movement was clearly initiated, the dominant stallions positioned themselves in the back of the group or in the center and had no influence on the direction of move that was only determined by the leading females. In the long-distance movements too, the small harem followed the large harem group, and the two bachelor males usually followed behind them. Social interactions included aggressive interactions between the two dominant males within the large harem or between dominant stallions and the two bachelor males accompanying the two harems. In addition, dominant males courting or attempting to mate with mares sometimes caused a turmoil that eventually initiated movement of the harems. KW -
|
|
|
|
Baumgartner M. (2012). Liegeverhalten von Pferden im Offenlaufstall auf unterschiedlichen Bodenmaterialien (Gummimatten, Späne und Sand) [Recumbency patterns of horses stabled in group housing systems on different bedding materials (rubber mats, shavings and sand)]. Ph.D. thesis, , Munich.
Abstract: Die angemessenste Art ein Pferd als soziales Wesen unter menschlicher Obhut zu halten, ist in der Gruppe mit Seinesgleichen. Dabei gilt der Offenlaufstall mit getrennten Funktionsbereichen (Mehrraum-Außenlaufstall mit Auslauf) als die tiergerechteste Haltungsform für Pferde (BMELV, 2009). Aus Gründen der Arbeits- und Kostenersparnis sowie zur Reduzierung der Keim- und Staubbelastung werden in jüngster Zeit vermehrt Gummimatten als Einstreuersatz in Liegehallen von Offenlaufställen eingesetzt.
In vorliegender Arbeit sollte überprüft werden, ob Gummimatten (7,5 cm hoch, schaumstoffgefüllt; HIT-Softbed plus®) in Kombination mit minimaler Späneeinstreu als Liegeunterlage in Liegehallen von Offenlaufställen als tiergerecht beurteilt werden können. Darüber hinaus galt es zu klären, ob die Klimaverhältnisse in den Liegehallen trotz nicht saugfähiger Gummiunterlage den hygienischen Anforderungen des BMELVs (2009) an das Stallklima entsprechen. Dazu wurde das Liegeverhalten von einer repräsentativen Anzahl von 56 Pferden in einem Offenlaufstall mit getrennten Funktionsbereichen an jeweils 6 Tagen je Jahreszeit (Frühling, Sommer, Herbst, Winter) mittels kontinuierlicher Videoaufzeichnungen (n= 24 Tage) und zusätzlichen visuellen Direkt-beobachtungen (n= 60 Std) erfasst. Die Pferde hatten zum Liegen die Wahl zwischen folgenden drei Arealen: drei identisch ausgestatteten, jedoch unterschiedlich großen Liegehallen (mittig Gummimatten; Randbereich Späneeinstreu), einem Unterstand (Sand), sowie einem Sandplatz. Die Größe der Liegefläche in den drei Liegehallen (LH I 172 m², LH II und III jeweils 143 m²) entsprach den Anforderungen des BMELVs (2009). Unterstand und Sandplatz konnten zusätzlich von den Pferden zum Ruhen im Liegen genutzt werden. Ergänzend wurden folgende Einflussfaktoren auf das Liegeverhalten der Pferde erfasst: Tageszeit, Jahreszeit und Witterung sowie Alter, Stockmaß, Gewicht, „Body Condition Score“ und Rangordnung.
Durchschnittlich ruhten lediglich 35,2 der 52,3 in der Anlage befindlichen Pferde (67,3%) pro Beobachtungstag im Liegen in den Arealen. Demzufolge nahmen
Zusammenfassung 213
viele Pferde nicht jede Nacht eine Liegeposition ein. Die Hauptliegezeit mit 72% der erfassten Liegephasen war zwischen 0 und 6 Uhr. Bezogen auf die vorhandene Liegefläche je Areal ergab sich lediglich eine 50%ige Maximalauslastung an gleichzeitig liegenden Pferden.
Die Liegephasendauer variierte -unabhängig vom Areal- signifikant zwischen den Pferden (p=0,028) und darüber hinaus auch je Pferd (p<0,001). Die durchschnittliche Dauer pro Liegephase war mit 28,8 ± 0,5 (SEM) min signifikant länger in den Liegehallen (I, II und III), als im Unterstand mit 24,6 ± 0,9 min und auf dem Sandplatz mit 20,0 ± 1,9 min (p<0,001).
Die mittlere tägliche Gesamtliegedauer eines Pferdes betrug 91 ± 2,7 min in den Liegehallen (I, II und III), 43 ± 2,3 min im Unterstand und 27 ± 2,9 min auf dem Sandplatz (p<0,001). In den Liegehallen legte sich ein Pferd im Mittel 3,2 Mal am Tag ab, im Unterstand lediglich 1,7 und auf dem Sandplatz 1,3 Mal (p<0,001). 79% der registrierten Liegephasen (n= 2410) fanden darüber hinaus in den Liegehallen (I, II und III) statt, was deren zentrale Bedeutung als Liegebereich hervorhebt.
In der größeren Liegehalle I ruhten eine größere Anzahl an unterschiedlichen Pferden häufiger (p<0,0002) und länger (p<0,0005) pro Tag im Liegen als in den beiden etwas kleineren Liegehallen II und III.
Die tägliche Gesamtliegedauer pro Pferd war mit aufgestütztem Kopf mit 54,8 ± 1,6 Minuten länger als ohne aufgestützten Kopf mit 45,2 ± 1,8 min. In Seitenlage wurde im Durchschnitt pro Tag und Pferd 27,5 ± 1,1 min geruht (p<0,001). Diese Ruheposition wurde in den Liegehallen signifikant häufiger eingenommen, als auf dem Sandplatz oder im Unterstand (p<0,001).
Die tägliche mittlere Gesamtliegedauer pro Pferd auf Späne war mit 74,3 ± 2,9 min gegenüber 62,4 ± 2,3 min auf Gummimatten signifikant länger (p=0,005). Ebenso fanden in Relation zum Flächenangebot in den Liegehallen geringfügig mehr Liegephasen auf dem Späne-Bereich als auf den Gummimatten statt. Ebenfalls in Flächenrelation wurde der offen gestaltete Unterstand deutlich vor den anderen Arealen zum Ruhen im Liegen von den Pferden präferiert. Es sei deshalb auf die Bedeutung eines Unterstandes als zusätzliche Liegefläche in Offenlaufstallhaltung hingewiesen.
Die meisten Liegephasen und auch die längsten täglichen Liegezeiten fanden in den warmen Monaten statt (p=0,013). Im Winter flachte das Ruhen im Liegen
deutlich ab und verlagerte sich bei unter -10°C nahezu ausschließlich auf die Liegehallen (p=0,001).
Der leichte Späne-Überzug und der positive Effekt der bereits integrierten und die Gummimatten zum Liegen nutzenden Pferde waren mögliche Gründe dafür, dass die Neuankömmlinge ohne Gummimatten-Vorerfahrung (n= 10 Pferde ≤ 6 Monate in der Anlage) kein vermindertes Liegeverhalten im Vergleich zur bestehenden Herde (n= 46 Pferde; mind. 1 bis max. 3 J. in der Anlage) aufwiesen.
Die Rangordnung wurde mittels modifiziertem „Average Dominance Index“ berechnet. Die rangniederen Pferde hatten mit 2,6 gegenüber 3,4 und 3,1 sowohl signifikant weniger Liegephasen pro Pferd und Tag, als auch mit 69,3 ± 3,9 min eine um 22 min signifikant kürzere tägliche Gesamtliegedauer als die Ranghöheren (jeweils p<0,001). Rangniedrige Pferde ruhten in den Liegehallen weniger häufig (2,7 gegenüber 3,5 und 3,2 mittlere Anzahl Liegephasen/ Pferd/ Tag) und auch signifikant (p<0,001) kürzer je Tag (77,8 ± 5,0 min gegenüber 97,3 ± 3,9 min und 98,8 ± 5,1 min). Je jünger ein Pferd war, desto öfter (3,5 gegenüber 2,6 mittlere Anzahl Liegephasen/ Pferd/ Tag) und länger (103,7 ± 7,6 min gegenüber 56,1 ± 13,2 min) legte es sich am Tag nieder, und desto häufiger (90% der Liegephasen der 4 und 5 Jährigen gegenüber 39% und 70% der 16 bis 25 J.) nutzte es die Liegehallen zum Liegen (p<0,001). Das Stockmaß der Pferde und das Pferdegewicht zeigten keinen eindeutigen Einfluss auf das Liegeverhalten. Für den „Body Condition Score“ (Skala 1 bis 9) ergaben sich signifikante Unterschiede. Je höher der BCS der Pferde war, desto häufigere (p=0,0185) und längere Liegezeiten (p=0,007) wiesen sie auf.
Der monatlich gemessenen Ammoniakgehalt sowie Luftgeschwindigkeit, Luftfeuchtigkeit und Temperatur entsprachen bei Einsatz von Gummimatten in den Liegehallen den Anforderungen des BMELV (2009) an ein tiergerechtes Stallklima. Voraussetzung hierfür ist jedoch eine ausreichende Luftzirkulation im Stallgebäude sowie eine gute Stallhygiene.
Die Ergebnisse aus den vergleichenden Beobachtungen der unterschiedlichen Liegematerialien lassen schlussfolgern, dass die hier untersuchten verformbaren Gummimatten in Kombination mit minimaler Späneeinstreu in Offenlaufställen von der Mehrzahl der Pferde zum Ruhen im Liegen angenommen wurde und deshalb als weitgehend tiergerecht beurteilt werden können.
[Being highly social animals, horses are housed most adequately in groups. Loose housing systems are said to be the most species adequate system of horse housing (BMELV, 2009). Recently rubber mats have increasingly been used instead of shavings as bedding in loose housing systems where the different functional areas are separated. Advantages of rubber mats are that they are less cost and labour intensive as shavings, and their use also reduces the bacterial and dust contamination of the environment.
However, it has not yet been shown whether horses are capable of satisfying their recumbency needs on rubber mats as well as they can on shavings. This study looks to clarify this question, as well as to evaluate the hygienic conditions of the stabling climate in the areas equipped with sponge-filled rubber mats (HIT-Softbed® plus).
The recumbency patterns of 56 horses kept in a loose housing system with separate functional areas were observed on 6 days per season (spring, summer, autumn and winter) using wide angle video cameras. The different areas were: three similar but different large halls meant as lying areas (in the middle rubber mats; in the periphery shavings), an unsheltered area with sand footing and a sheltered area with sand footing. The size of the three halls meant as lying areas (LH I 172 m², LH II and III each 143 m²) was adequate with the demands of the BMELV (2009). Confounding factors which could also affect recumbency behaviour, such as day time, season and weather were taken into account. The role of the horses rank was also investigated. The occurrence of disruptions during recumbency phases by other members of the herd was also found out. Horse specific factors such as age, height, weight and body condition score were also taken into account as these could also have an effect on recumbency patterns.
On each day of observation, in average 35 different horses out of 56 horses (65%) were seen to be resting in a recumbent position. Hence many horses did not assume a recumbent position every night. Seventy-two percent of the recumbency
phases occurred between 0 and 4 am. The capacity of the area for a lying position at one time offered the horses was only exploited to 50%.
The length of the recumbency phase varied significantly between animals and for the individual animals over the duration of the observation period (p<0.001). The average recumbent time per lying phase was 28.8 ± 0.5 (SEM) minutes in the halls (I, II and III), 24.6 ± 0.9 min in the shelter and 20.0 ± 1.9 min on the sand area. The average time spent lying down per horse per day was 91 ± 2.7 min in the halls, 43 ± 2.3 min in the shelter and 27 ± 2.9 min on the sand area (p<0.001). The horses lay down an average of 3.2 times in the halls, 1.7 times in the shelter and 1.3 times in the sand area (p<0.001). Seventy-nine percent of the observed recumbency phases (n= 2410) were seen in the halls. This shows that along with the pastures, the halls played a central role in the recumbency patterns of the horses.
When comparing the halls, a wider variety of horses was observed spending a longer time in recumbency (p<0.0005) more often (p<0.0002) in hall I than in the somewhat smaller halls II and III.
The total time spent per day in recumbency with the head supported was 54.8 ± 1.6 min and hence was ten minutes longer than the total daily time spent in recumbency without the head supported with 45.2 ± 1.8 min. On average the horses spent 27.5 ± 1.1 min in lateral recumbency (p<0.001). Horses were observed to lie in lateral recumbency more often in the halls than on sand area or in the shelter (p<0.001).
The daily total length of time spent in recumbency was found to be significantly longer on bedding (74.3 ± 2.9 min) versus on rubber mats (62.4 ± 2.3 min) (p=0.005). Even though the average number and length of recumbency periods per day and horse, as well as the average time spent in lateral recumbency was greater for the halls, when taking surface area into consideration, it was found that the sheltered area was used the most per surface area for resting in recumbency. Hence it is relevant to state the importance of a shelter as additional lying space in loose housing systems.
The highest number of recumbency phases and the longest time spent daily lying down were seen in the mild months of the year (p=0.013). Temperatures below freezing led to decreased recumbency behavior. The horses observed lay down
almost exclusively in the halls when temperature was below -10°C (p<0.001).
The newcomers (n= 10 horses ≤ 6 months in the stable) to this housing system did not show a diminished recumbency behaviour compared to the other horses (n= 46 horses for 1 to 3 years in the stable). It is apparent that horses that do not have previous experience of rubber mats do not necessitate an adaptation period to use the mats to lay down on, as long as they are introduced into a group of horses that are already comfortable with the use of the mats. Likewise the shavings could help the horses adapt to the new material faster.
The rank of the horse in the herd was determined using a modified “Average Dominance Index”. The horses of low rank showed a significantly lower number of recumbency phases (2.6 compared to 3.4 and 3.1 per horse per day), as well as with 69.3 ± 3.9 min a highly significant shorter by 22 minutes length of recumbency phase when compared to horses of higher rank (each p<0.001). With diminishing rank, the horses lay down less frequently in the halls (2.7 compared to 3.5 and 3.2 recumbency phases per horse per day) and the total daily time spent in recumbency (77.8 ± 5.0 min compared to 97.3 ± 3.9 min und 98.8 ± 5.1 min) diminished significantly (p<0.001). Younger horses were found to lie down more frequently (3.5 compared to 2.6 recumbency phases per horse per day) but also to spend significantly longer periods (103.7 ± 7.6 min compared to 56.1 ± 13.2 min) in recumbency (p<0.001). Younger horses also tended to (90% of recumbency phases of 4 and 5 year old compared to 39% and 70% of 16 until 25 year old) use the halls for recumbent periods of rest (p<0.001). Horse height and weight did not influence recumbency behavior clearly. An interesting correlation was however noted with “body condition score” (BCS). A scale from 1 to 9 was used. The higher the BCS, the more (p=0.0185) and longer (p=0.007) time the animal spent resting in recumbency.
Air ammonia content, air velocity, ambient humidity and temperature measured monthly were within the recommendations of the BMELV (2009). Rubber mats are of no concern to hygiene when used as bedding in loose housing systems with segregated functional areas, as long as sufficient air circulation and proper stable hygiene are present.
The results of the comparative observations of the various bedding materials lead us to conclude that the currently studied rubber mats in combination with a
minimum amount of shaving are accepted by the majority of the horses and therefore are a widely species-appropriate bedding material for horses in loose housing systems.]
|
|
|
|
Austin, N. P., & Rogers, L. J. (2012). Limb preferences and lateralization of aggression, reactivity and vigilance in feral horses, Equus caballus. Anim. Behav., 83(1), 239–247.
Abstract: Observational field studies were conducted on two remote populations of feral horses in Australia to determine whether lateralization is a characteristic of Equus caballus as a species or results from handling by humans. Group 1 had been feral for two to five generations and Group 2 for 10–20 generations. In both groups, left-side biases were present during agonistic interactions and in reactivity and vigilance. Therefore, as in other vertebrates, the right hemisphere appears to be specialized to control agonistic behaviour and responses to potential threats. The leftwards bias was stronger in measures of behaviour involving more aggression and reactivity. Preferences to place one forelimb in front of the other during grazing were also determined. No population bias of forelimb preference was found, suggesting that such limb preferences present in domestic horses may be entrained. Since stronger individual limb preferences were found in immature than in adult feral horses, limb preference may be modified by maturation or experience in the natural habitat. Stronger limb preference was associated significantly with elevated attention to the environment but only in younger feral horses. No sex differences in lateralization were found. The findings are evidence that horses show visual lateralization, as in other vertebrates, not dependent on handling by humans. Limb preference during grazing, by contrast, does appear to depend on experience.
|
|
|
|
Conradt, L. (2012). Models in animal collective decision-making: information uncertainty and conflicting preferences. Interface Focus, 2(2), 226–240.
Abstract: Collective decision-making plays a central part in the lives of many social animals. Two important factors that influence collective decision-making are information uncertainty and conflicting preferences. Here, I bring together, and briefly review, basic models relating to animal collective decision-making in situations with information uncertainty and in situations with conflicting preferences between group members. The intention is to give an overview about the different types of modelling approaches that have been employed and the questions that they address and raise. Despite the use of a wide range of different modelling techniques, results show a coherent picture, as follows. Relatively simple cognitive mechanisms can lead to effective information pooling. Groups often face a trade-off between decision accuracy and speed, but appropriate fine-tuning of behavioural parameters could achieve high accuracy while maintaining reasonable speed. The right balance of interdependence and independence between animals is crucial for maintaining group cohesion and achieving high decision accuracy. In conflict situations, a high degree of decision-sharing between individuals is predicted, as well as transient leadership and leadership according to needs and physiological status. Animals often face crucial trade-offs between maintaining group cohesion and influencing the decision outcome in their own favour. Despite the great progress that has been made, there remains one big gap in our knowledge: how do animals make collective decisions in situations when information uncertainty and conflict of interest operate simultaneously?
|
|
|
|
Palme, R. (2012). Monitoring stress hormone metabolites as a useful, non-invasive tool for welfare assessment in farm animals. Animal Welfare, 21(3), 331–337.
Abstract: A multitude of endocrine mechanisms are involved in coping with challenges. Glucocorticoids, secreted by the adrenal glands, are in the front line of the battle to overcome stressful situations. They are usually measured in plasma samples as parameters of adrenal activity and thus of disturbance. Unfortunately, collecting blood samples itself can disturb an animal. Thus, non-invasive methods for the determination of glucocorticoids or their metabolites have become increasingly popular. The pros and cons of various non-invasive sample materials (saliva, excreta, milk, hair/feathers and eggs) for glucocorticoid determination are given. Above all, faecal samples offer the
advantage that they can be collected easily. In faecal samples, circulating hormone levels are integrated over a certain period of time and represent the cumulative secretion of hormones. Thus, the levels are less affected by short fluctuations or the pulse-like nature of hormone secretion. However, using this technique to assess an animal’s adrenocortical activity is not especially simple. Whether frequent sampling is necessary or single samples will suffice depends upon the study’s aim (whether one is examining the impact of acute or chronic stressors). Background knowledge of the metabolism and excretion of cortisol/corticosterone metabolites is required and a careful validation for each species and sex investigated is obligatory. The present review also addresses analytical issues regarding sample storage, extraction procedures and immunoassays and includes a comprehensive list of published studies (up to 2011) describing the use of such methods in farmed animals. Applied properly, non-invasive techniques to monitor glucocorticoid metabolites in faecal samples of various species are a useful tool for welfare assessment, especially as they are easily applied at farm or group level.
|
|
|
|
Galaverni, M., Palumbo, D., Fabbri, E., Caniglia, R., Greco, C., & Randi, E. (2012). Monitoring wolves (Canis lupus) by non-invasive genetics and camera trapping: A small-scale pilot study. Eur J Wildl Res, 58.
|
|
|
|
Briefer, E. F., Padilla de la Torre, M., & McElligott, A. G. (2012). Mother goats do not forget their kids' calls. Proc R Soc B, 279.
|
|
|
|
Stanley, C., & Shultz, S. (2012). Mummy’s Boys: Sex Differential Maternal Offspring Relationships in Semi-feral Horses. In K. Krueger (Ed.), Proceedings of the 2. International Equine Science Meeting (Vol. in press). Wald: Xenophon Publishing.
Abstract: In polygynous species with high reproductive skew in males, mothers often show differential investment between sons and daughters; however consistent sex differential investment has not been found by previous studies in horses. We investigated sex differences in mother-offspring relationships in nutritionally independent sub-adult semi-feral Carneddau Welsh mountain ponies Equus ferus caballus. Mothers and their sub-adult sons had consistently closer relationships than mothers and daughters. Stronger affiliative bonds between mothers and sons were quantified by their maintenance of closer proximity, higher rates of affiliative interactions and more frequent suckling bouts. These measures of affiliation were temporally associated with higher aggression levels directed towards sub-adults by other band members, particularly stallions. We suggest that aggression may serve as the proximate mechanism driving male dispersal in feral horses and that the stronger mother-son bond signals an attempt to delay their dispersal, highlighting conflict within the band concerning dispersal timing. Since males become increasingly central within the band over time, with mature stallions requiring excellent social skills in order to both acquire and keep a band of mares, we propose that delaying colts' dispersal allows for further development of these skills in a relatively safe environment. This additional investment is expected to maximise their reproductive success. This study illustrates how social network theory can be used to quantify individuals' social experiences, contributing to a greater understanding of the evolution of group living. It also gives us further insight into the mechanisms underlying dispersal in wild and semi-wild horse populations and how conflict often arises when individual needs differ.
|
|
