Small Carcasses Research Articles

Activity and social interactions in a wide-ranging specialist scavenger, the Tasmanian devil (Sarcophilus harrisii), revealed by animal-borne video collars

Observing animals directly in the field provides the most accurate understanding of animal behaviour and resource selection. However, making prolonged observation of undisturbed animals is difficult or impossible for many species. To overcome this problem for the Tasmanian devil (Sarcophilus harrisii), a cryptic and nocturnal carnivore, we developed animal-borne video collars to investigate activity patterns, foraging behaviour and social interactions. We collected 173 hours of footage from 13 individual devils between 2013 and 2017. Devils were active mostly at night, and resting was the most common behaviour in all diel periods. Devils spent more time scavenging than hunting and exhibited opportunistic and flexible foraging behaviours. Scavenging occurred mostly in natural vegetation but also in anthropogenic vegetation and linear features (roads and fence lines). Scavenging frequency was inversely incremental with size e.g. small carcasses were scavenged most frequently. Agonistic interactions with conspecifics occurred most often when devils were traveling but also occurred over carcasses or dens. Interactions generally involved vocalisations and brief chases without physical contact. Our results highlight the importance of devils as a scavenger in the Tasmanian ecosystem, not just of large carcasses for which devils are well known but in cleaning up small items of carrion in the bush. Our results also show the complex nature of intraspecific interactions, revealing greater detail on the context in which interactions occur. In addition, this study demonstrates the benefits of using animal-borne imaging in quantifying behaviour of elusive, nocturnal carnivores not previously seen using conventional field methods.

Delaying insect access alters community composition on small carrion: a quantitative approach

AbstractWe present a study of interactions in the highly competitive insect communities inhabiting the carrion of small mammals. Via manipulation in a fully quantitative design, we delayed community development by excluding insect colonization in mouse and rat carcasses for 3 days, to study the role of early competitively dominant colonizers [burying beetles (Nicrophorus spp.; Coleoptera: Silphidae) and blowfly larvae (Diptera: Calliphoridae)] in the course of heterotrophic succession on small cadavers. Earlier studies demonstrated that in the case of large mammalian carrion, exclusion of insects’ access to the carcass in the early stages of decomposition altered the successional trajectory and species assemblages. However, the effect of such manipulation in easy monopolizable small vertebrate carrion remained unknown. Our results demonstrate that delaying insect access to carrion significantly lowered blowfly larvae abundances, while it simultaneously had no effect on colonization and carrion burial by burying beetles. Higher abundances of blowfly larvae seem to deter necrophagous beetles, whereas they are not harmful to the larvae of flesh flies, at least in larger rat carcasses. Predatory beetle species preferred the lower abundances of blowfly larvae, presumably due to better accessibility of their prey. Our results therefore suggest that in the course of the entire season, larvae of blowflies are the dominant competitors in small carcasses, and significantly affect the assembly of other insect groups, whereas burying beetles may exhibit a more temporal pattern of dominance.

Impacts of a concentrated solar power trough facility on birds and other wildlife in South Africa

This study assesses bird and wildlife mortality and changes in bird species communities at a 50 MW utility-scale concentrated solar power parabolic trough facility in South Africa. The facility was searched for evidence of large vertebrate mortalities over three months. Eight bird carcasses were recorded in the solar field, all of which probably died prior to the study period. Carcass persistence trials indicated that 94% of bird carcasses survived 24 h, 68% for 7 d, and 56% for 28 d, although persistence varied with carcass size. No large carcasses (>1 000 g) were removed entirely by scavengers after 28 d, whereas only 42% of medium-sized (100–1 000 g) and 17% of small (<100 g) carcasses remained after 28 d. Searchers detected 72% of bird carcasses, with large birds more likely to be detected than small birds. The extrapolated mortality rate for the facility was 3.9 birds y−1 (90% CI 0.0–14.9) or 0.1 bird fatalitites MW y−1 (90% CI 0.0–0.3). Birds were much more abundant (141.9 birds km−1) and species rich (51 species) in the surrounding rangeland than in the solar field (1.27 birds km−1; 22 species). Of the 24 bird carcasses found in the evaporation ponds, six likely drowned (four species). Three reptiles (one species) and 12 mammals (seven species), including sensitive species such as aardvark Orycteropus afer, also drowned in the evaporation ponds. This is the first study of its kind in South Africa and unexpectedly revealed that the evaporation ponds had a bigger impact on wildlife than anticipated.

Using multiple data sources to investigate foraging niche partitioning in sympatric obligate avian scavengers

AbstractAs carrion feeders competing for a limited and ephemeral resource, avian scavengers are ideal model organisms to study mechanisms of niche partitioning. Previous work has focused on observations of species’ interactions at carcasses, and although fruitful, the inclusion of behavior beyond that at carcasses, such as movement patterns, could yield a more comprehensive understanding of mechanisms of foraging niche partitioning. Our goal was to assess how differences in physiological, morphological, and social characteristics between sympatric black vultures (Coragyps atratus) and turkey vultures (Cathartes aura) manifest interspecific variation in movement patterns, foraging habitats, and carcass use to reduce direct competition. Both species are obligate scavengers that co‐occur across much of the New World. Turkey vultures are solitary foragers with enhanced olfactory capabilities and wings optimized for energy‐efficient low‐altitude soaring. Black vultures are aggressive, heavier bodied, and forage socially. We assessed interspecific variation in carcass exploitation using experimental carcass trials encompassing a range of habitats, carcass sizes, and seasons, and used GPS telemetry to compare how soaring conditions influenced daily space use and diurnal patterns of movement activity for each species. Turkey vultures occurred more often at small (i.e., rabbit) carcasses, and those obscured by forest cover than black vultures, and were the first vultures recorded at 94% of carcasses visited by both species. Both species increased movement rates and daily ranges when soaring conditions were favorable; however, turkey vultures had higher travel rates regardless of soaring conditions. Our results suggest the olfactory sense of turkey vultures allows them to locate smaller and visually obscured carcasses more efficiently than black vultures, facilitated by wing morphology that allows them to forage over large areas efficiently. Socially foraging black vultures appear specialized at locating larger carcasses in open habitats, which does not require as much foraging flight as turkey vultures. Our study illustrates how inclusion of movement ecology into niche partitioning studies provides a more complete understanding of the mechanisms of coexistence in avian scavenger guilds. This approach may provide important information to guide conservation efforts, such as supplemental feeding, of imperiled vulture species.

The early-life environment and individual plasticity in life-history traits.

We tested whether the early‐life environment can influence the extent of individual plasticity in a life‐history trait. We asked: can the early‐life environment explain why, in response to the same adult environmental cue, some individuals invest more than others in current reproduction? Moreover, can it additionally explain why investment in current reproduction trades off against survival in some individuals, but is positively correlated with survival in others? We addressed these questions using the burying beetle, which breeds on small carcasses and sometimes carries phoretic mites. These mites breed alongside the beetle, on the same resource, and are a key component of the beetle's early‐life environment. We exposed female beetles to mites twice during their lives: during their development as larvae and again as adults during their first reproductive event. We measured investment in current reproduction by quantifying average larval mass and recorded the female's life span after breeding to quantify survival. We found no effect of either developing or breeding alongside mites on female reproductive investment, nor on her life span, nor did developing alongside mites influence her size. In post hoc analyses, where we considered the effect of mite number (rather than their mere presence/absence) during the female's adult breeding event, we found that females invested more in current reproduction when exposed to greater mite densities during reproduction, but only if they had been exposed to mites during development as well. Otherwise, they invested less in larvae at greater mite densities. Furthermore, females that had developed with mites exhibited a trade‐off between investment in current reproduction and future survival, whereas these traits were positively correlated in females that had developed without mites. The early‐life environment thus generates individual variation in life‐history plasticity. We discuss whether this is because mites influence the resources available to developing young or serve as important environmental cues.

Effect of Hot Carcass Weight on the Rate of Temperature Decline of the Longissimus Dorsi and Semimembranosus of Pigs Slaughtered in a Blast-Chilled Commercial Abattoir

ObjectivesOver the last 30 yr, the average hot carcass weight (HCW) has consistently increased by approximately 0.5 kg per yr. This trend toward increased HCW causes engineering challenges for aging facilities designed when average HCW was 85 kg, in contrasts to today’s average HCW of 95 kg. The rate of carcass chilling is among the primary concerns. Larger carcasses have a smaller surface area to volume ratio, and almost certainly do not reach desired internal temperatures at the same rate as smaller carcasses. However, differences in rate have not been routinely reported, and to the authors’ knowledge, no such model has been reported for a large-scale, blast-chilled pork abattoir. Therefore, the objective of this study was to model the effect of HCW on temperature decline of a contemporary population of pork carcasses slaughtered at a commercial abattoir that used a blast-chilling method. Additionally, carcasses were sorted into HCW classes and the effect of HCW group was tested on the rate of temperature decline of the longissimus dorsi and semimembranosus.Materials and MethodsHot carcass weight, internal temperature of the loin muscle (at the 10th rib) and ham, as well as ambient temperature, were recorded from 40 to 1,320 min postmortem (45 time points) on 754 pork carcasses. An exponential decay model based on Newton’s Law of Cooling, was fit to temperature decline of the ham and loin of the whole population using PROC MODEL of SAS (SAS Inst. Inc., Cary, NC). The initial models for the decline of both ham and loin temperature displayed significant autocorrelation of errors based on evaluation of the autocorrelation function plots and Durbin-Watson test (P < 0.0001). Therefore, second and third order autocorrelation parameters were tested. Based on Durbin-Watson tests, the use of second order autocorrelation model with lags of 1 and 2 were deemed adequate and were therefore included in all subsequent models. This base model and its respective parameter estimates were all significant (P < 0.01) for the whole population. Carcasses approximating (± 1 kg) 85, 90, 95, 100, and 105 kg were selected and binned into their respective weight classes. Dummy variables were used to compare the effect of HCW class on parameter estimate of ham and loin models.ResultsThe developed model significantly fit all weight classes (P < 0.01) for both ham and loin temperature decline. For both loin and ham models, estimates of the rate constant (k) generally decreased as HCW increased. For loin temperature, k estimate for 105 kg carcasses was 0.00124 less (P = 0.02) than 85 kg carcasses, with the intermediate HCW classes not differing from the 85 kg class. For ham temperature, estimates of k for 90, 95, 100, and 105 kg HCW were all significantly and successively less than the k estimate for 85 kg class. For perspective, loins of 95 kg carcasses were estimated to reach 2°C in 17 h; whereas, loins from 105 kg carcasses would not reach 2°C until 27 h. For hams, 95 kg carcasses were projected to reach 2°C in 21 h; whereas, those from 105 kg carcasses would take 28 h. These estimates generally agreed with observed values.ConclusionOverall, HCW significantly affects the rate of temperature decline of pork hams, but not loins from pork carcasses weighing between 85 and 100 kg. This method of analysis can be used to model temperature decline in individual facilities.

The effect of body size on skeletal articulation and completeness in Jurassic Ichthyopterygia (Reptilia)

A taphonomic investigation of Jurassic ichthyopterygians from the Posidonienschiefer Formation initially supports the common assumption of better preservation with increasing body size. However, there is also an obvious increase in the range of preservational states with decreasing body size, suggesting greater susceptibility of smaller carcasses to the effects of biostratinomic processes. An investigation of articulation and completeness separately against body size indicates a stronger link of completeness to preservation; bigger elements were more difficult to move. Size ranges, which crucially relate to ontogenetic stages, suggest the extent of disarticulation and loss of completeness is greater in juvenile and embryonic skeletons (less than 200 cm ±) compared to those of adults (over 200 cm). The study has important implications for the preservation of different body size ranges, in particular, those representing ontogenetic stages in ichthyopterygians and other marine reptile groups, but, more generally, for vertebrates entering the fossil record.

Resource availability, but not polyandry, influences sibling conflict in a burying beetle Nicrophorus vespilloides

Conflict over resources is a fundamental component of family life. Family conflicts are predicted to be strongly influenced by resource availability and levels of relatedness between family members. Here, we examined the effects of these factors on intra-brood sibling conflict in a family living beetle, Nicrophorus vespilloides, where offspring are partially dependent on parental provisioning. Specifically, we measured the intensity of offspring begging behavior in response to experimental manipulation of 1) relatedness between siblings (through mating females monogamously or polyandrously) and 2) resource availability (through varying the amount of resources at the onset of breeding). We found no effect of polyandry on sibling conflict or patterns of female reproductive investment, but we did find that sibling conflict was influenced by resource availability. Specifically, larvae spent more time begging on smaller carcasses, but only in smaller clutches. In addition, we found that resource availability affected patterns of female reproductive investment: when resource availability was low, females laid eggs more synchronously and produced fewer eggs but of a larger size. We discuss potential explanations for these results, and the implications of this study for understanding the factors that mediate family dynamics.

Decomposition rate of intact and injured piglet cadavers

The popular assumption persists that wounded or injured carcasses and by association human bodies, provide enhanced attraction and opportunity for the oviposition of forensically important flies and therefore lead to accelerated putrefaction. Recent studies, however, contradict this assumption. In this study piglet carcasses were exposed in early spring and late summer to ensure seasonal comparability of decay. To assess possible influencing factors injuries of varying depths were inflicted postmortem (e.g. abrasions, superficial and deeper lacerations of the skin) and additional blood was applied onto wounds. It could be confirmed for small piglet carcasses that injuries and trauma might have an influence on the pattern of decomposition but not on the rate of decomposition. The data gained might be valuable in estimating postmortem intervals for babies or small children.

Carcasses of invasive species are predominantly utilized by invasive scavengers in an island ecosystem

AbstractInvasive species have significantly affected ecosystems, particularly islands, and species invasions continue with increasing globalization. Largely unstudied, the influence of invasive species on island ecosystem functions, especially scavenging and decomposition, could be substantive. Quantifying carcass utilization by different scavengers and shifts in community dynamics in the presence of invasive animals is of particular interest for understanding impacts on nutrient recycling. Invasive species could benefit greatly from carcass resources within highly invaded island ecosystems, through increased invasion success and population growth, subsequently exacerbating their impacts on native species. We quantified how experimentally placed invasive amphibian, reptile, small mammal, and bird carcasses were utilized by vertebrate and invertebrate scavengers on the Big Island of Hawai'i in three island habitats: a barren lava field, a vegetated lava field, and a rainforest. We used camera traps to record vertebrate scavengers removing carcasses and elapsed time until removal. We evaluated differences in scavenging between vertebrates and invertebrates and within the vertebrate community across different habitats and carcass types. Despite the small carcass sizes (&lt;1 kg) used in this study, 55% of carcasses were removed by vertebrate scavengers, all invasive: mongoose, rodents, cats, pigs, and a common myna. Our data indicate that invasive vertebrate scavengers in this island ecosystem are highly efficient at assimilating a range of carrion resources across a variety of habitats. Carcasses of invasive animals could contribute substantially to energy budgets of other invasive vertebrate species. This may be a critical component contributing to successful invasions especially on islands and subsequent impacts on ecosystem function.

Evolution of elaborate parental care: phenotypic and genetic correlations between parent and offspring traits.

The evolution of elaborate forms of parental care is an important topic in behavioral ecology, yet the factors shaping the evolution of complex suites of parental and offspring traits are poorly understood. Here, we use a multivariate quantitative genetic approach to study phenotypic and genetic correlations between parental and offspring traits in the burying beetle Nicrophorus vespilloides. To this end, we recorded 2 prenatal traits (clutch size and egg size), 2 postnatal parental behaviors (direct care directed toward larvae and indirect care directed toward resource maintenance), 1 offspring behavior (begging), and 2 measures of breeding success (larval dispersal mass and number of dispersing larvae). Females breeding on larger carcasses provided less direct care but produced larger larvae than females breeding on smaller carcasses. Furthermore, there were positive phenotypic correlations between clutch size, direct, and indirect care. Both egg size and direct care were positively correlated with dispersal mass, whereas clutch size was negatively correlated with dispersal mass. Clutch size and number of dispersed larvae showed genetic variance both in terms of differences between populations of origin and significant heritabilities. However, we found no evidence of genetic variance underlying other parental or offspring traits. Our results suggest that correlations between suites of parental traits are driven by variation in individual quality rather than trade-offs, that some parental traits promote offspring growth while others increase the number of offspring produced, and that parental and offspring traits might respond slowly to selection due to low levels of additive genetic variance.

Searcher efficiency and survey coverage affect precision of fatality estimates

Studies at renewable energy sites often attempt to estimate avian and bat fatalities or fatality rates (e.g., fatalities/megawatt [MW]/year). However, searcher efficiency and level of survey effort among sites are variable. We evaluated how searcher efficiency and proportion of area surveyed affected precision of fatality estimates and probability of detecting rare fatalities (e.g., fatalities of an endangered species). We measured searcher-efficiency rates of human and dog-handler teams for 3 fatality types: feather spots, small carcasses, and large carcasses. We also created high and low searcher-efficiency scenarios to evaluate effects of searcher efficiency across a broader range. Model selection on a set of logistic regression models for our empirical trials supported search team and fatality type as important predictors of searcher-efficiency rates, and demonstrated that dog-handler teams had higher searcher efficiency for all fatality types than human search teams. We used model simulations to evaluate fatality estimates obtained across the 4 searcher-efficiency scenarios and 10 levels of survey coverage: 10–100%, in increments of 10%. At each level of survey coverage, width of confidence intervals decreased as searcher efficiency increased; however, as survey coverage increased, width of the confidence intervals stabilized, and further increases in coverage did not lead to increases in precision. Average fatality estimates were biased positively and this bias increased with lesser searcher efficiency. The survey coverage necessary to achieve 80% detection probability for rare fatalities (defined as 1, 5, or 15 fatalities) decreased as searcher efficiency increased for all fatality types. When a rare fatality was defined as a single fatality out of 1,000, an 80% detection probability was achieved only by dog-handler teams and the high searcher-efficiency scenario, and only for large carcasses. Our results emphasize the need for managers and agencies to consider study objectives and site characteristics when selecting level of survey coverage, type of search team, and other options to maximize searcher efficiency. © 2016 The Wildlife Society.

Scavenging of small bird carrion in southwestern Germany by beetles, birds and mammals

When considering the impact of wind turbines on the mortality of birds and bats, it is important to know the length of time that a carcass will be detectable. Thousands of small animals (such as many passerine birds with high mortality rates) die every day, but dead animals are rarely found by casual observers in the field. What is the fate of small carcasses in European ecosystems? During this project, we placed 120 defrosted day-old chicks (Gallus gallus f. domestica) as a model for a small carcass in a variety of habitats in southwestern Germany between the end of May and the beginning of December 2014. Using automatic trail cameras, we recorded the scavengers which visited the carrion or were feeding on it. Overall, two-thirds of the carcasses were removed under these conditions within a 5-day period. During the summer months, 20 % of the chicks were buried by burying beetles (Nicrophorus sp.), and 40 % were removed by nine mammal and three bird species. The most important vertebrate scavengers were the Red Fox (Vulpes vulpes), the Common Buzzard (Buteo buteo), the European Magpie (Pica pica) and the Domestic Cat (Felis catus). Among the scavenged chicks, 38.8 % vanished during the first 24 h of exposure. The median persistence time was 2.79 days. Persistence times were not dependent on habitat type, but carrion persisted longer on average in autumn than in summer. Knowledge of the factors influencing carcass persistence is important for estimating mortality in songbirds or bats in the context of wind turbines.

Interspecific interactions change the outcome of sexual conflict over prehatching parental investment in the burying beetle Nicrophorus vespilloides

Sexual conflict arises when the optimal reproductive strategy differs for males and females. It is associated with every reproductive stage, yet few studies have considered how the outcome may be changed by interactions with other species. Here, we show that phoretic mites Poecilochirus carabi change the outcome of sexual conflict over the supply of prehatching parental investment in the burying beetle Nicrophorus vespilloides. Burying beetles require a small dead vertebrate for reproduction, which they prepare by shaving it, rolling up the flesh, and burying it. When pairs were given a medium‐sized mouse to prepare (13–16 g), mites changed how the costs of reproduction were divided between the sexes, with males then sustaining greater costs than females. We found no equivalent difference when pairs prepared larger or smaller carcasses. Thus, our experiment shows that the outcome of sexual conflict over prehatching parental investment is changed by interactions with other species during reproduction.

Niche variation and the maintenance of variation in body size in a burying beetle

1. In burying beetles (Nicrophorinae), body size is known to provide both a fecundity advantage (in females) and successful resource defence (in males and females). Despite this, considerable variation in body sizes is observed in natural populations.2. A possible explanation for the maintenance of this variation, even with intra‐ and inter‐specific resource competition, is that individuals might assort according to body size on different‐sized breeding resources.3. We tested prediction that ‘bigger is always better’, in the wild and in the laboratory, by experimentally manipulating combinations of available breeding‐resource size (mouse carcasses) and competitor's body size in Nicrophorus vespilloides (Herbst 1783).4. In the field, large female beetles deserted small carcasses, without breeding, more often than they did larger carcasses, but small females used carcasses indiscriminately with respect to size. In the laboratory, large beetles reared larger broods (with more offspring) on larger carcasses than small beetles, but on small carcasses small beetles had a reproductive advantage over large ones. Offspring size covaried with carcass size independently of parental body size.5. The present combined results suggest breeding resource value depends on an individual's body size, and variation in body size is environmentally induced: maintained by differences in available carcass sizes. This produces a mechanism by which individual specialisation leads to an increase in niche variation via body size in these beetles.

Effect of body mass and clothing on carrion entomofauna.

Carcass mass largely affects pattern and rate of carrion decomposition. Supposedly, it is similarly important for carrion entomofauna; however, most of its likely effects have not been tested experimentally. Here, simultaneous effects of carcass mass and clothing are analyzed. A factorial block experiment with four levels of carcass mass (small carcasses 5–15 kg, medium carcasses 15.1–30 kg, medium/large carcasses 35–50 kg, large carcasses 55–70 kg) and two levels of carcass clothing (clothed and unclothed) was made in a grassland habitat of Western Poland. Pig carcasses (N = 24) were grouped into spring, early summer, and late summer blocks. Insects were sampled manually and with pitfall traps. Results demonstrate that insect assemblages are more complex, abundant, and long-lasting on larger carcasses, whereas clothing is of minor importance in this respect. Only large or medium/large carcasses were colonized by all guilds of carrion insects, while small or medium carcasses revealed high underrepresentation of late-colonizing insects (e.g., Cleridae or Nitidulidae). This finding indicates that carcasses weighing about 23 kg—a standard in forensic decomposition studies—give an incomplete picture of carrion entomofauna. Residencies of all forensically relevant insects were distinctly prolonged on larger carcasses, indicating that cadaver mass is a factor of great importance in this respect. The pre-appearance interval of most taxa was found to be unrelated to mass or clothing of a carcass. Moreover, current results suggest that rate of larval development is higher on smaller carcasses. In conclusion, this study demonstrates that carcass mass is a factor of crucial importance for carrion entomofauna, whereas the importance of clothing is small.

Empirical Evidence for Factors Affecting Searcher Efficiency and Scavenging Rates at a Coastal, Terrestrial Wind-Power Facility

Abstract The rapid expansion of wind power development in recent years has accentuated the need to develop standard guidelines for identifying, assessing, and monitoring potential impacts to birds and bats. Although postconstruction mortality estimates generally take into account well-established sources of bias, including searcher efficiency and scavenging loss, methods for addressing these biases can be improved. Currently used bias-adjustment methods differ across studies, do not explicitly account for factors that may affect initial bias estimates, and often use averaged or assumed levels of bias. We examined scavenging and detection trial data from a 3-y study at a small, terrestrial wind-farm in coastal New Jersey. Logistic regression models indicated that carcass size, substrate, and observer all affected carcass detection rates, with larger carcasses more likely to be detected than smaller carcasses, and those located on bare ground or grass more likely to be detected than those on gravel. Known-fate mark–recapture models indicated that scavenging rates were highest within the first 3 d of placement, with some variation among seasons. We suggest that empirically based estimates of factors affecting observer detection and scavenging loss be generated for individual wind-farm mortality studies, because they likely vary across sites and could heavily bias resulting adjustment factors and mortality estimates.

Juvenile hormone, metabolic rate, body mass and longevity costs in parenting burying beetles

Levels of juvenile hormone (JH) are elevated during parental care in burying beetles (Nicrophorus) at a time when ovarian activity is suppressed, suggesting that JH plays an alternative role to its better known gonadotropic function. Because parental activity in burying beetles is time-intensive, it might be expected to be energetically stressful and to impart longevity costs. We predicted that the active (feeding) stage of care would be associated with elevated JH and greater energy expenditure (higher metabolic rate, lower body mass), and that this stress would result in shorter life span. Parents experimentally manipulated into providing more care for young had increased levels of JH. For females, there was a significant longevity cost associated with parental care but not with mating or egg production. During carcass preparation, females and males that would later regurgitate to larvae showed an initial increase in body mass followed by a significant decrease in mass during the intense period of parental provisioning of young (during and just after the JH peak). Males that provided little care (on small carcasses with a female partner) showed no such anticipatory weight gain. An indirect measure of metabolic rate (VCO2) was nearly twice as high in caregiving females compared to nonbreeding females. These results suggest that the energy demands and/or high JH levels during care extract a significant cost on longevity. We propose that JH has evolved to play a novel role in parental care in burying beetles associated with extreme energy demands during feeding of offspring.

Carcass permanency time and its implications to the roadkill data

Roadkill studies are typically conducted without regard to the carcass permanency time on the highway, which may lead to underestimation of roadkill data, especially small animals that are quickly removed by scavengers. To evaluate the carcass duration time on the lane and its relation to the roadkill time event, we conducted an experiment comparing the removal rate of small carcasses between different stretches of a highway and stretches of dirt roads. The rates found in the study were considered high, with 89 % of carcasses being removed in the first 24 h and 66 % within 12 h. The removals were high for both road categories but reached their peaks at different periods of the day, being higher during the day on the highway and at night on dirt roads. We believe that removal on the highway is dictated by higher vehicular traffic and mainly by the action of scavenger birds during the day, while on dirt roads, it is due to the action of different opportunistic scavengers during the night.

Effect of body mass and clothing on decomposition of pig carcasses.

Carcass mass and carcass clothing are factors of potential high forensic importance. In casework, corpses differ in mass and kind or extent of clothing; hence, a question arises whether methods for post-mortem interval estimation should take these differences into account. Unfortunately, effects of carcass mass and clothing on specific processes in decomposition and related entomological phenomena are unclear. In this article, simultaneous effects of these factors are analysed. The experiment followed a complete factorial block design with four levels of carcass mass (small carcasses 5–15 kg, medium carcasses 15.1–30 kg, medium/large carcasses 35–50 kg, large carcasses 55–70 kg) and two levels of carcass clothing (clothed and unclothed). Pig carcasses (N = 24) were grouped into three blocks, which were separated in time. Generally, carcass mass revealed significant and frequently large effects in almost all analyses, whereas carcass clothing had only minor influence on some phenomena related to the advanced decay. Carcass mass differently affected particular gross processes in decomposition. Putrefaction was more efficient in larger carcasses, which manifested itself through earlier onset and longer duration of bloating. On the other hand, active decay was less efficient in these carcasses, with relatively low average rate, resulting in slower mass loss and later onset of advanced decay. The average rate of active decay showed a significant, logarithmic increase with an increase in carcass mass, but only in these carcasses on which active decay was driven solely by larval blowflies. If a blowfly-driven active decay was followed by active decay driven by larval Necrodes littoralis (Coleoptera: Silphidae), which was regularly found in medium/large and large carcasses, the average rate showed only a slight and insignificant increase with an increase in carcass mass. These results indicate that lower efficiency of active decay in larger carcasses is a consequence of a multi-guild and competition-related pattern of this process. Pattern of mass loss in large and medium/large carcasses was not sigmoidal, but rather exponential. The overall rate of decomposition was strongly, but not linearly, related to carcass mass. In a range of low mass decomposition rate increased with an increase in mass, then at about 30 kg, there was a distinct decrease in rate, and again at about 50 kg, the rate slightly increased. Until about 100 accumulated degree-days larger carcasses gained higher total body scores than smaller carcasses. Afterwards, the pattern was reversed; moreover, differences between classes of carcasses enlarged with the progress of decomposition. In conclusion, current results demonstrate that cadaver mass is a factor of key importance for decomposition, and as such, it should be taken into account by decomposition-related methods for post-mortem interval estimation.