Behaviour and animal welfare indicators of broiler chickens housed in an enriched environment

The present study aimed to assess the influence of adding straw bales, step platforms, and laser projectors as environmental enrichment resources on the behaviour and welfare indicators of broiler chickens (Gallus gallus domesticus). A sample of 4,000 day-old male Cobb® 500 birds was used. The experimental treatments consisted of No Environmental Enrichment (NEE)—similar to a conventional environment; and Environmental Enrichment (EE)—environment enriched with straw bales, step platforms, and laser projectors, with four replicates per treatment of 500 animals. Behavioural characteristics (ethological observation through cameras, grab test, and modified touch test) and animal welfare indicators (pododermatitis and dorsal cranial myopathy) were assessed. The birds submitted to the EE treatment exhibited greater exploratory activity and expression of behaviours associated with comfort and welfare, whereas those in the NEE group were less active. Locomotion and play fighting behaviour decreased and behaviours associated with comfort increased as age advanced. The frequencies of interaction with laser spots and birds lying around straw bales were the highest in the 1st week (P<0.01). The behaviours of pecking at straw bales (P<0.0004), using the step platforms (P = 0.0001) and being on top of straw bales (P<0.0002) gradually increased. The chickens accessed the feeding troughs the most in the period of 0800 hours (P<0.0001) and expressed the highest frequencies of behaviours associated with comfort in the 1400 hours and 1700 hours periods. The birds in the EE group were calmer in face of human presence and touch and scored higher in animal welfare indicators. Adding straw bales, step platforms, and laser projectors increased locomotion, reduced expression of fear, and improved animal welfare indicators of broiler chickens.

Fighting over defence chemicals disrupts mating behaviour

Studies on intraspecific contest behaviour predominantly focus on contests between individuals of the same sex, however contest behaviour is also expected to occur between individuals of the opposite sex including possible mates. Here we investigate potential trade-offs between mating and fighting behaviour in the turnip sawfly (Athalia rosae). Adults of this species collect chemical defence compounds (clerodanoids) directly from plants but also indirectly by nibbling on conspecifics that have already obtained clerodanoids themselves, a highly aggressive behavioural interaction. An A. rosae individual without clerodanoids may therefore be the potential mate or attacker of an individual of the opposite sex that has gained clerodanoids. We paired males and females with or without clerodanoid access and manipulated body mass differences between the sexes via the early life starvation of females. We show that asymmetrical clerodanoid acquisition between male-female pairs causes an increase in agonistic nibbling behaviour, irrespective of sex. Moreover, fighting over clerodanoids disrupted mating behaviour, and the frequency of aggressive nibbling behaviour in these pairs was determined by the comparative body mass of the attacking individual. Our study highlights the vital importance of investigating agonistic intersex interactions not only over mating but also over resources.

Fighting Behaviour of Male Onion Thrips, Thrips tabaci (Thysanoptera: Thripidae) Lineages

Onion thrips, Thrips tabaci Lindeman, 1889 (Thysanoptera: Thripidae) has three distinctive reproductive modes: arrhenotokous, thelytokous and deuterotokous. This experiment was focused on the arrhenotokous leek-(L1) and tobacco-associated (T) T. tabaci lineages. These two lineages are distinctively varied genetically and in host adaptations. L1 and T lineages perform better on leek and tobacco plants, respectively. Fighting occurs between males when they compete for food, mating, and oviposition sites. The aim of this research was to examine the fighting behaviour and characterize the fighting elements of males in L1 and T lineages. The experiment was performed in the laboratory by using a Euromex VC.3036 video camera and each experiment was recorded for a duration of 10 minutes. Transparent PCR tube caps formed the arena to observe the fighting interactions in both lineages. A total of 40 video recordings have been observed and each recording had a different arena. The fighting performance was observed at 2, 5, 8, 10, 12 days old specimens in four replications. This result has shown L1 lineage had better fighting performance and a more aggressive fighting ability than T lineage. Antennal bouts, jumping, flipping, stabbing and pitching are the most commonly observed fighting elements.

Allometry and Fighting Behaviour of a Dimorphic Stag Beetle Cyclommatus mniszechi (Coleoptera: Lucanidae)

Male stag beetles (Coleoptera: Lucanidae) use their mandibles as weapons to compete for resources and reproduction. Mandible size in stag beetles can be associated with different behaviours and the outcome of male contests. We investigated the allometric relationship between mandible and body size in males of the stag beetle Cyclommatus mniszechi to uncover distinct morphs. The results divided male C. mniszechi into majors and minors with the switch point of mandible length at 14.01 mm. The allometric slope of mandibles was positive for both morphs but was steeper for the minors. We also characterised the fighting behaviour of the different morphs in size-matched contests using sequential analyses. Males matched each other’s behaviour in contests with many physical contacts, no injury and a progression from low towards high aggression and rare de-escalation. Major and minor males employed the same behavioural elements in contests, but major males were more likely to escalate directly into more aggressive phases and minor males tended to stay within phases. This finding suggests that major males may compete more aggressively than minor males in contests.

Pleiotropy promotes male exaggerated weapon and its associated fighting behaviour in a water strider

Exaggerated sexually selected traits, often carried by males, are characterized by the evolution of hyperallometry, resulting in their disproportionate growth relative to the rest of the body 1–3. While the evolution of allometry has attracted much attention for centuries, our understanding of the developmental genetic mechanisms underlying its emergence remains fragmented 4,5. Here we show that the hyperallometric legs in the males of the water strider Microvelia longipes are associated with a specific signature of gene expression during development. Using RNAi knockdown, we demonstrate that a broadly expressed growth factor, Bone Morphogenetic Protein 11 (BMP11, also known as Growth Differentiation Factor 11), regulates leg allometries through increasing the allometric coefficient and mean body size in males. In contrast, BMP11 RNAi reduced mean body size but did not affect slope in females. Furthermore, our data show that a tissue specific factor, Ultrabithorax (Ubx), increases intercept without affecting mean body size. This indicates a genetic correlation between mean body size and variation in allometric slope, but not intercept. Strikingly, males treated with BMP11 RNAi exhibited a severe reduction in fighting frequency compared to both controls and Ubx RNAi-treated males. Overall, we demonstrate a genetic correlation between male body size, the exaggerated weapon, and the intense fighting behaviour associated with it in M. longipes. Our results provide evidence for a role of pleiotropy in the evolution of allometric slope.

Head to head: the case for fighting behaviour in Megaloceros giganteus using finite-element analysis

The largest antlers of any known deer species belonged to the extinct giant deer Megaloceros giganteus . It has been argued that their antlers were too large for use in fighting, instead being used only in ritualized displays to attract mates. Here, we used finite-element analysis to test whether the antlers of M. giganteus could have withstood forces generated during fighting. We compared the mechanical performance of antlers in M. giganteus with three extant deer species: red deer ( Cervus elaphus ), fallow deer ( Dama dama ) and elk ( Alces alces ). Von Mises stress results suggest that M. giganteus was capable of withstanding some fighting loads, provided that their antlers interlocked proximally, and that their antlers were best adapted for withstanding loads from twisting rather than pushing actions, as are other deer with palmate antlers. We conclude that fighting in M. giganteus was probably more constrained and predictable than in extant deer.

Is camera trap videography suitable for assessing activity patterns in eastern grey kangaroos?

Camera traps are frequently used in wildlife research and may be a useful tool for monitoring behavioural patterns. The suitability of camera traps to monitor behaviour depends on the size, locomotion, and behaviour of the species being investigated. The suitability of cameras for documenting the behaviour of eastern grey kangaroos was assessed here by comparing activity patterns collected using cameras to published activity patterns for the species. The activity patterns calculated from camera trap data were largely consistent with data from previous studies, although nocturnal activity appeared to be under-represented. Observations of unusual fighting behaviour illustrates the potential for camera traps to enable capture of novel observations. Kangaroo behaviour appeared to be influenced by the presence of cameras; however, no kangaroos retreated from cameras. Data suggested that kangaroos became habituated to cameras after eight months. The findings of this study suggest that camera traps are suitable for assessing the diurnal activity of eastern grey kangaroos and are useful tools for documenting their behaviour.