Reduced Body Condition Research Articles

Widespread exposure to lead affects the body condition of free-living whooper swans Cygnus cygnus wintering in Britain

Lead poisoning, through the ingestion of spent lead gunshot, is an established cause of morbidity and mortality in waterbirds globally, but the thresholds at which blood levels begin to affect the physiology of birds in the wild are less well known. Here we determine the prevalence of lead exposure in whooper swans and, for the first time, identify the level of blood lead associated with initial reductions in body condition. Blood lead elevated above background levels (i.e. >20 μg dL−1) was found in 41.7% (125/300) of swans tested. Blood lead was significantly negatively associated with winter body condition when levels were ≥44 μg dL−1 (27/260 = 10%). Our findings indicating that sub-lethal impacts of lead on body condition occur at the lower end of previously established clinical thresholds and that a relatively high proportion of individuals in this population may be affected, reaffirm the importance of reducing contamination of the environment with lead shot.

Small mammals as sentinels of oil sands related contaminants and health effects in northeastern Alberta, Canada

The extraction of bitumen in areas of northeastern Alberta (Canada) has been associated with the release of complex mixtures of metals, metalloids, and polycyclic aromatic compounds (PACs) to the environment. To mitigate effects on ecosystems, Canadian legislation mandates that disturbed areas be reclaimed to an ecologically sustainable state after active operations. However, as part of reclamation activities, exposure to, and effects on wildlife living in these areas is not generally assessed. To support successful reclamation, the development of efficient methods to assess exposure and health effects in potentially exposed wildlife is required. In the present study, we investigated the usefulness of two native mammalian species (deer mouse Peromyscus maniculatus, and meadow vole Microtus pennsylvanicus) as sentinels of oil sands related contaminants by examining biomarkers of exposure and indicators of biological costs. Tissue residues of 31 metals and metalloids in kidneys and muscle, activity of the hepatic detoxification enzyme EROD (as a biomarker of exposure to organic contaminants), body condition, and the relative mass of liver, kidney, spleen, and testes were compared in animals from one reclaimed area and a reference site. Deer mice from the reclaimed site had higher renal levels of Co, Se and Tl compared to animals from the reference site, which was associated with reduced body condition. Lower testis mass was another feature that distinguished mice from the reclaimed site in comparison to those from the reference site. One mouse and one vole from the reclaimed site also showed increased hepatic EROD activity. In marked contrast, no changes were evident for these variables in meadow voles. Our results show that deer mouse is a sensitive sentinel species and that the biomarkers and indicators used here are efficient means to detect local contamination and associated biological effects in native mammals inhabiting reclaimed areas on active oil sands mine sites. These field-derived findings can be used by risk assessors to fill possible data gaps for mammalian wildlife in science-based environmental risk assessments for oil and gas projects.

Individual and demographic consequences of reduced body condition following repeated exposure to high temperatures

Individual and demographic consequences of reduced body condition following repeated exposure to high temperatures

Pollutant accumulation patterns in nestlings of an avian top predator: biochemical and metabolic effects

The exposure to persistent pollutants such as organochlorine compounds (OCs) or metals has been associated with declines in top predator populations, which can accumulate high amounts of these pollutants from their prey. However, understanding how variation in OC and metal accumulation in wild species affects their biochemical and physiological responses is a big challenge, especially for endangered predators like the Bonelli's eagle (Aquila fasciata). This bird of prey is an interesting study model because the differences in diet composition among populations and territories can account for important pollutant uptake variations. We compared OC and metal accumulation in blood of Bonelli's eagle nestlings from three populations across Spain as a function of origin, age class (nestlings vs. adults), sex and number of siblings per nest, and related accumulation patterns to responses indicative of body condition, biochemistry and antioxidant status. Nestlings from Catalonia, the most industrialized area, showed the highest concentrations of PCBs and arsenic, and the lowest concentrations of zinc. The two former substances, together with DDTs, exerted an overall influence on nestling's physiology. PCBs and arsenic were associated with reduced retinol levels, pointing to oxidative damage in exposed individuals, which was also consistent with the low zinc levels in individuals from the polluted region. Increased plasma DDT levels were related to reduced body condition and lower levels of triglycerides. Mercury accumulation in Castile and Leon was higher in nestlings that were alone in the nest than in nestlings that shared it with a sibling; this suggests an increased mercury uptake from secondary prey in territories where preferred prey (i.e. rabbits) are scarce, which are also the territories where productivity is reduced. Overall, the results reveal a spatial variation in pollutant accumulation patterns and associated physiological effects, and suggest the major role that territory quality may have in such patterns.

Enhanced biological processes associated with alopecia in polar bears (Ursus maritimus)

Populations of wildlife species worldwide experience incidents of mass morbidity and mortality. Primary or secondary drivers of these events may escape classical detection methods for identifying microbial insults, toxin exposure, or additional stressors. In 2012, 28% of polar bears sampled in a study in the southern Beaufort Sea region of Alaska had varying degrees of alopecia that was concomitant with reduced body condition. Concurrently, elevated numbers of sick or dead ringed seals were detected in the southern Beaufort, Chukchi, and Bering seas in 2012, resulting in the declaration of an unusual mortality event (UME) by the National Oceanic and Atmospheric Administration (NOAA). The primary and possible ancillary causative stressors of these events are unknown, and related physiological changes within individual animals have been undetectable using classical diagnostic methods. Here we present an emerging technology as a potentially guiding investigative approach aimed at elucidating the circumstances responsible for the susceptibility of certain polar bears to observed conditions. Using transcriptomic analysis we identified enhanced biological processes including immune response, viral defense, and response to stress in polar bears with alopecia. Our results support an alternative mechanism of investigation into the causative agents that, when used proactively, could serve as an early indicator for populations and species at risk. We suggest that current or classical methods for investigation into events of unusual morbidity and mortality can be costly, sometimes unfocused, and often inconclusive. Advances in technology allow for implementation of a holistic system of surveillance and investigation that could provide early warning of health concerns in wildlife species important to humans.

Invasive cane toad triggers chronic physiological stress and decreased reproductive success in an island endemic

Summary Understanding the mechanisms that afford invasive species their ecological success as important agents of global change is key to addressing their biodiversity impacts. Species invasions that occur on small islands are especially detrimental and suggest that invaders intensify their ecological impacts by exploiting novel ecological functions. However, it remains unknown whether such strong impacts are also a consequence of an invader's indirect effect (e.g. causing physiological stress or reproductive failure) on island species. Therefore, it is valuable to quantify the physiological mechanisms through which invasive species can exert indirect effects on the performance, and ultimately the fitness of island endemics. In this study, we investigated whether the invasive cane toad (Rhinella marina) caused indirect competitive impacts on the endemic Fijian ground frog (Platymantis vitiana) on the small (60 ha) Viwa Island, Fiji. We used large (4 × 10 000 m2), natural and replicated enclosures to monitor ground frog stress hormone levels, reproductive hormone cycle, body condition, breeding and survival in the presence/absence of the cane toad. We conducted monthly sampling to analyse annual patterns in testosterone for males, estradiol and progesterone for females, corticosterone for both sexes and body condition of ground frogs in replicated enclosures or natural habitats with high/low cane toad densities. We also measured survival and reproductive success of ground frogs in enclosures. Results showed that in both enclosures and natural habitats with high cane toad densities, ground frogs had a significant reduction in body condition, increased urinary corticosterone metabolites and suppressed sex steroid metabolites. Most importantly, annual field surveys showed significant reduction in ground frog reproductive success (fewer eggs were laid in enclosures with toads present); however, survival was not severely reduced. Our study clearly demonstrated that on small islands, invasive species may exploit broader ecological roles with strong indirect effects that amplify their impacts beyond those seen on continents. Overall, the effects of cane toad competition had the capacity to strongly reduce ground frog reproductive success. We strongly advocate management actions that either minimize invasion or limit the strength of invasive–native species interactions (e.g. through habitat conservation) to prevent further extinctions on islands.

Effects of bottom trawling on fish foraging and feeding

The effects of bottom trawling on benthic invertebrates include reductions of biomass, diversity and body size. These changes may negatively affect prey availability for demersal fishes, potentially leading to reduced food intake, body condition and yield of fishes in chronically trawled areas. Here, the effect of trawling on the prey availability and diet of two commercially important flatfish species, plaice (Pleuronectes platessa) and dab (Limanda limanda), was investigated over a trawling intensity gradient in the Irish Sea. Previous work in this area has shown that trawling negatively affects the condition of plaice but not of dab. This study showed that reductions in local prey availability did not result in reduced feeding of fish. As trawling frequency increased, both fish and prey biomass declined, such that the ratio of fish to prey remained unchanged. Consequently, even at frequently trawled sites with low prey biomass, both plaice and dab maintained constant levels of stomach fullness and gut energy contents. However, dietary shifts in plaice towards energy-poor prey items were evident when prey species were analysed individually. This, together with a potential decrease in foraging efficiency due to low prey densities, was seen as the most plausible cause for the reduced body condition observed. Understanding the relationship between trawling, benthic impacts, fish foraging and resultant body condition is an important step in designing successful mitigation measures for future management strategies in bottom trawl fisheries.

Chilled frogs are hot: hibernation and reproduction of the Endangered mountain yellow-legged frog Rana muscosa

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 27:43-51 (2015) - DOI: https://doi.org/10.3354/esr00648 Chilled frogs are hot: hibernation and reproduction of the Endangered mountain yellow-legged frog Rana muscosa Frank E. Santana1,2, Ronald R. Swaisgood1,*, Jeffrey M. Lemm1, Robert N. Fisher3, Rulon W. Clark2 1San Diego Zoo Institute for Conservation Research, 15600 San Pasqual Valley Road, Escondido, CA 92027, USA 2Department of Biology, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, USA 3US Geological Survey, San Diego Field Station, 4165 Spruance Road, Suite 200, San Diego, CA 92101, USA *Corresponding author: rswaisgood@sandiegozoo.org ABSTRACT: In the face of the sixth great extinction crisis, it is imperative to establish effective breeding protocols for amphibian conservation breeding programs. Captive efforts should not proceed by trial and error, nor should they jump prematurely to assisted reproduction techniques, which can be invasive, difficult, costly, and, at times, counterproductive. Instead, conservation practitioners should first look to nature for guidance, and replicate key conditions found in nature in the captive environment, according to the ecological and behavioral requirements of the species. We tested the effect of a natural hibernation regime on reproductive behaviors and body condition in the Endangered mountain yellow-legged frog Rana muscosa. Hibernation had a clear positive effect on reproductive behavior, manifesting in vocal advertisement signaling, female receptivity, amplexus, and oviposition. These behaviors are critical components of courtship that lead to successful reproduction. Our main finding was that captive R. muscosa require a hibernation period for successful reproduction, as only hibernated females produced eggs and only hibernated males successfully fertilized eggs. Although hibernation also resulted in a reduced body condition, the reduction appeared to be minimal with no associated mortality. The importance of hibernation for reproduction is not surprising, since it is a major component of the conditions that R. muscosa experiences in the wild. Other amphibian conservation breeding programs can also benefit from a scientific approach that tests the effect of natural ecological conditions on reproduction. This will ensure that captive colonies maximize their role in providing genetic reservoirs for assurance and reintroduction efforts. KEY WORDS: Hibernation · Amphibian · Assurance colony · Captive breeding · Reproductive behavior Full text in pdf format PreviousNextCite this article as: Santana FE, Swaisgood RR, Lemm JM, Fisher RN, Clark RW (2015) Chilled frogs are hot: hibernation and reproduction of the Endangered mountain yellow-legged frog Rana muscosa . Endang Species Res 27:43-51. https://doi.org/10.3354/esr00648 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 27, No. 1. Online publication date: February 11, 2015 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2015 Inter-Research.

Can a Blood-Feeding Ectoparasitic Fly Affect Songbird Migration? Examining Body Condition and Fat Reserves of Five Bird Species in Relation to Hippoboscid Fly Parasitism

Background. Migratory birds are often faced with the challenge of undertaking long-distance journeys while harboring parasites. Objective. I investigated the possibility that Hippoboscid flies (Diptera, Hippoboscidae), blood-feeding ectoparasites, would be associated with reduced body condition or fat reserves of migratory songbirds. Methods. I mist-netted songbirds on an island off the southern coast of Nova Scotia, Canada during fall 1996 and noted the presence of hippoboscid flies on five focal species. Of 731 individuals, 60 (8.2%) had flies. Results. In statistical models that considered species and parasitism, I found no effect of flies on body condition, but birds with flies had significantly reduced fat reserves. This pattern was found in all species to varying degrees. Conclusions. While these results do not confirm causality, they are consistent with the idea that parasitized birds suffer a cost to their migratory preparations. It is unclear whether the birds were in a premigratory stage or actually migrating, although reductions in fat in either case would be costly. This study highlights how host-parasite interactions must be studied in multiple life stages to gain a complete understanding of their nature.

Climate Change and Livestock Nutrient Availability: Impact and Mitigation

Climate Change and Livestock Nutrient Availability: Impact and Mitigation Livestock is an integral part of any agricultural system all over the world. Optimized livestock production is depended upon many factors like environmental stresses, climatic factors, health status, nutrient availability, and genetic potential. In the changing climate scenario, nutritional stress act as the most important indirect stress affecting livestock leading to decreased performance, lower efficiency, increased mortality and it also affects the immune system. The animals in tropics faces the problem of low feed availability during summer and this leads to severe nutritional stress to livestock grazing in the low pasture lands. Under nutrition reduces the quality and quantity of milk production, effects growth potential and reduces body condition score (BCS), induces seasonal weight loss (SWL) and it also declines the reproductive capacity of the animals, it reduces the fertility rate, embryo quality, expression of oestrus behaviour, altering follicular development, compromising oocyte competence, and inhibiting embryonic development, reduced calf birth weight, reduced sperm output, decreased sperm motility and an increased proportion of morphologically abnormal spermatozoa in the ejaculate. The reduced nutrient availability also alters the endocrine and hormonal activity in livestock leading to physiological changes and decline in reproductive efficiency. The animals exposed to environmental stress are found to cope up with the adverse effects of the stress when the nutritional requirements are not compromised. Thus in order to sustain the productivity, suitable nutritional interventions are to be adopted like management of forage for the dry period, utilization of the non-conventional feed resources as alternatives, antioxidant supplementations during the stress period, and also water management strategies for both surface and ground water resources, at both local and national levels, as fresh and contamination free water is crucial for animal production. These efforts will ensure economically viable returns in livestock farms in the changing climate scenario..

Individual variation in the oxidative costs of personality traits

Summary ‘Personality traits’ are behavioural differences between individuals that are stable within individuals. Different combinations of personality traits can correlate with fitness variation but the mechanisms remain unclear. There is the suggestion that personality reflects variation in physiology. For example, ‘fast’ (bold, active, fast exploring) individuals are predicted to maintain a higher metabolic rate than ‘slow’ animals. A raised metabolic rate can result in a proliferation of reactive oxygen species (ROS) which, if unchecked, cause oxidative stress. Thus, the ‘extended pace of life theory’ predicts that ‘fast’ individuals will pay higher oxidative costs than ‘slow’ ones. Alternatively, stress hormones, which are often relatively high in ‘slow’ individuals, can also cause proliferation of ROS and subsequent oxidative damage. Here, we assessed co‐variation between personality and oxidative profile in wild blue tits. The personality traits neophobia (latency to approach food near novel objects), activity level in a novel environment and exploratory tendency (controlling for differences in activity) assayed in captivity were repeatable within individuals but were uncorrelated with each other. Reactive oxygen metabolites (ROMs an index of pro‐oxidant status) and OXY (antioxidant capacity) were also uncorrelated with each other and did not vary with age or sex. Blood sampling birds within three minutes of capture from their familiar cage vs. after 15 min of exposure to a standardized stressor did not affect ROMs or OXY. Wintering blue tits that were both highly neophobic and exploratory had low OXY defences and individuals that showed low neophobia and low exploration had high OXY defences. Variation in ROMs was not explained by any personality trait. High exploratory tendency also correlated with a reduction in body condition in captivity, but body condition did not predict ROMs or OXY. Activity level in the exploration trial did not vary with oxidative profile or change in body condition. Personality types differed in antioxidant defences, and it was the combination of an individual's personality traits that proved important. ROS production and antioxidant defences will vary due to many processes for example resource allocation, not just metabolic rate and stress responsiveness. Consequently, the costs of personality traits and thus the predictions regarding fitness are complex.

English

The Delta Smelt, an endangered fish, has suffered a long-term decline in abundance, believed to result from, in part, to changes in the pelagic food web of the upper San Francisco Estuary. To investigate the current role of food as a factor in Delta Smelt well- being, we developed reference criteria for gut fullness and body condition based on allometric growth. We then examined monthly diet, prey selectivity, and gut fullness of larvae and juvenile Delta Smelt collected April through September in 2005 and 2006 for evi- dence of feeding difficulties leading to reduced body condition. Calanoid copepods Eurytemora affinis and Pseudodiaptomus forbesi remained major food items during spring and from early summer through fall, respectively. Other much larger copepods and mac- roinvertebrates contributed in lesser numbers to the diet of older juvenile fish from mid-summer through fall. In fall, juvenile Delta Smelt periodically relied heavily on very small prey and prey potentially associated with demersal habitat, suggesting typical pelagic food items were in short supply. We found a strong positive selection for E. affinis and P. forbesi, neutral to negative selection for evasive calanoid Sinocalanus doerrii, and neutral to negative selection for the small cyclopoid copepod Limnoithona tetra- spina and copepod nauplii, which were consumed only when extremely numerous in the environment. Feeding incidence was significantly higher in 2006, but among successfully feeding fish we found no between year difference in gut fullness. However, we did detect differences in fullness across months in both years. We found no difference in body condition of Delta Smelt between years yet our sample sizes were low in September when Delta Smelt reverted to feeding on very small organisms and fullness declined, so the longer-term effect remains unknown. Our findings suggest that: Delta Smelt had difficulty obtaining prey in spring 2005 or obtaining proper- sized prey in fall of both years. We detected these difficulties in some regional feeding incidence and fullness indices, but not in body condition indices.

Paternal programming in sticklebacks

In a wide range of organisms, including humans, mothers can influence offspring via the care they provide. Comparatively little is known about the effects of fathering on offspring. Here, we test the hypothesis that fathers are capable of programming their offspring for the type of environment they are likely to encounter. Male threespine sticklebacks, Gasterosteus aculeatus, were either exposed to predation risk while fathering or not. Fathers altered their paternal behaviour when exposed to predation risk, and consequently produced adult offspring with phenotypes associated with strong predation pressure (smaller size, reduced body condition, reduced behavioural activity). Moreover, more attentive fathers produced offspring that showed stronger antipredator responses. These results are consistent with behaviourally mediated paternal programming: fathers can alter offspring phenotypes to match their future environment and influence offspring traits well into adulthood.

Response of stream salamanders to experimental drought in the southern Appalachian Mountains, USA

Droughts act as significant disturbances to freshwater animals and their ecosystems. Given the impending threat of more frequent and persistent droughts because of global climate change, the lack of data on the responses of many aquatic animals to drought is a cause for concern. This study examined the body condition of the most commonly detected species (Desmognathus quadramaculatus) and abundance of commonly found species after two years of experimental drought in two first-order streams in the southern Appalachian Mountains. Our results indicated negative effects of drought on the stream salamander community. The body condition of D. quadramaculatus larvae in experimental drought transects was significantly lower than larvae captured in control reaches, which may have resulted from lower macroinvertebrate production in experimental reaches. Additionally, larval D. quadramaculatus abundance declined 47% in experimental drought transects, and Eurycea wilderae larvae and D. ocoee adults were 70% less likely to be captured in experimental stream transects. Our findings contribute additional evidence that stream plethodontids have little resistance to drought. With extended droughts resulting from climate change more likely in the future, more research is necessary to determine if reduced body condition, production, and lowered abundance have effects on long-term population viability.

Intra-sexual competition alters the relationship between testosterone and ornament expression in a wild territorial bird

In a reliable signalling system, individual quality is expected to mediate the costs associated with ornamental displays, with relatively lower costs being paid by individuals of higher quality. These relative costs should depend not only on individual quality, but also on levels of intra-sexual competition. We explored the current and delayed effects that testosterone implants have on bird ornamentation in populations with contrasted population densities, as a proxy for intra-sexual competition. In a replicated experiment, we manipulated testosterone in 196 yearling male red grouse Lagopus lagopus scoticus in autumn in populations of high and low levels of intra-sexual competition. Males were assigned to one of three exogenous testosterone (T) treatments: empty implants (T0), small T implants (T1) or larger T implants (T2). We monitored subsequent changes in testosterone levels, ornament size and carotenoid-based colouration, carotenoid levels and body condition from autumn to spring. Testosterone implants increased testosterone levels, comb redness and comb size, and decreased body condition but these effects depended on levels of intra-sexual competition. Specifically, T2-implanted birds increased testosterone levels and comb size more, and reduced body condition more, in populations where intra-sexual competition was low. In the following spring, testosterone levels of T2-treated birds kept increasing in populations where intra-sexual competition was high but not in populations where intra-sexual competition was low. Our results highlight that levels of intra-sexual competition alter the relationship between testosterone levels and ornament expression, influencing their condition-dependence; they also indicate that the outcome of standard hormone manipulation conducted in free-living animals vary depending on the population context.

Plastic ingestion by Flesh-footed Shearwaters (Puffinus carneipes): Implications for fledgling body condition and the accumulation of plastic-derived chemicals

To provide much needed quantitative data on the lethal and sublethal effects of plastic pollution on marine wildlife, we sampled breast feathers and stomach contents from Flesh-footed Shearwater (Puffinus carneipes) fledglings in eastern Australia. Birds with high levels of ingested plastic exhibited reduced body condition and increased contaminant load (p < 0.05). More than 60% of fledglings exceed international targets for plastic ingestion by seabirds, with 16% of fledglings failing these targets after a single feeding (range: 0.13–3.21 g of plastic/feeding). As top predators, seabirds are considered sentinels of the marine environment. The amount of plastic ingested and corresponding damage to Flesh-footed Shearwater fledglings is the highest reported for any marine vertebrate, suggesting the condition of the Australian marine environment is poor. These findings help explain the ongoing decline of this species and are worrying in light of increasing levels of plastic pollution in our oceans.

Chilled frogs are hot: hibernation and reproduction of the endangered mountain yellow-legged frog Rana muscosa

In the face of the sixth great extinction crisis, it is imperative to establish effective breeding protocols for amphibian conservation breeding programs. Captive efforts should not proceed by trial and error, nor should they jump prematurely to assisted reproduction techniques, which can be invasive, difficult, costly, and, at times, counterproductive. Instead, conservation practitioners should first look to nature for guidance, and replicate key conditions found in nature in the captive environment, according to the ecological and behavioral requirements of the spe- cies. We tested the effect of a natural hibernation regime on reproductive behaviors and body con- dition in the Endangered mountain yellow-legged frog Rana muscosa. Hibernation had a clear positive effect on reproductive behavior, manifesting in vocal advertisement signaling, female receptivity, amplexus, and oviposition. These behaviors are critical components of courtship that lead to successful reproduction. Our main finding was that captive R. muscosa require a hiberna- tion period for successful reproduction, as only hibernated females produced eggs and only hiber- nated males successfully fertilized eggs. Although hibernation also resulted in a reduced body condition, the reduction appeared to be minimal with no associated mortality. The importance of hibernation for reproduction is not surprising, since it is a major component of the conditions that R. muscosa experiences in the wild. Other amphibian conservation breeding programs can also benefit from a scientific approach that tests the effect of natural ecological conditions on reproduc- tion. This will ensure that captive colonies maximize their role in providing genetic reservoirs for assurance and reintroduction efforts.

Comparison of peripartum metabolic status and postpartum health of Holstein and Montbéliarde-sired crossbred dairy cows

Objectives of the current experiment were to evaluate plasma concentrations of metabolites and haptoglobin peripartum, uterine health and involution, and follicle growth and resumption of cyclicity of Holstein (HO) and Montbéliarde-sired crossbred cows. Cows (52 HO and 52 crossbred) were enrolled in the study 45 d before expected calving date. Cows had body weight and body condition score recorded on d −45, −14, 0, 1, 28, and 56 relative to calving. Dry matter intake was calculated for a subgroup of cows (25 HO and 38 crossbred) from 6 wk before to 6 wk after calving. Blood was sampled weekly from d −14 to 56 relative to calving for determination of glucose, nonesterified fatty acid, and β-hydroxybutyrate concentrations; from d −7 to 21 relative to calving for determination of haptoglobin concentration; and from d 14 to 56 postpartum for determination of progesterone concentration. Cows were examined at calving and on d 4, 7, 10, and 14 postpartum for diagnosis of postparturient diseases, on d 24 postpartum for diagnosis of purulent vaginal discharge, and on d 42 postpartum for diagnosis of subclinical endometritis. Uteri and ovaries were examined by ultrasonography every 3 d from d 14 to 41 postpartum. Milk yield and composition were measured monthly and yield of milk, fat, protein, and energy-corrected milk were recorded for the first 90 d postpartum. Body weight was not different between Holstein and crossbred cows, but HO cows had reduced body condition score compared with crossbred cows. Even though DMI from 6 wk before to 6 wk after calving tended to be greater for HO cows (16.8±0.7 vs. 15.3±0.5kg/d), HO cows tended to have more pronounced decline in dry matter intake, expressed in percentage of body weight from d −15 to 0 relative to calving. Energy-corrected milk and nonesterified fatty acid and β-hydroxybutyrate concentrations were not different between breeds. No differences were observed in incidence of retained fetal membranes, metritis, and subclinical endometritis, but HO cows tended to be more likely to have pyrexia from d 0 to 15 postpartum (50.0 vs. 31.4%) and to have greater incidence of purulent vaginal discharge (44.2 vs. 26.5%) than crossbred cows. Holstein cows were more likely to have at least 1 uterine disorder postpartum than crossbred cows (63.5 vs. 36.7%). No differences between breeds were observed in uterine involution. Holstein cows had larger subordinate follicles (10.1±0.4 vs. 8.9±0.5) and a greater number of class III follicles (1.6±0.1 vs. 1.2±0.1) than crossbred cows. Furthermore, the first corpus luteum postpartum of HO cows was diagnosed at a slower rate compared with crossbred cows. Crossbred cows had improved uterine health compared with HO cows and this may have been a consequence of heterosis and (or) breed complementarity and less pronounced decrease in DMI during the last days of gestation.

The Effects of Embeddedness on the Seasonal Feeding of Mottled Sculpin

Excess sediment in streams (measured as embeddedness), whether from natural or anthropogenic sources, has adverse effects on the biota that inhabit these systems. Aquatic macroinvertebrates exhibit reductions in diversity and abundance, which in turn leads to a reduction in the availability and quality of food for their fish predators; however, macroinvertebrate communities were not significantly different from one another. The predator-prey relationship between mottled sculpin (Cottus bairdii) and macroinvertebrates was examined in four headwater streams with differing embeddedness levels (15% and 35%) in Garrett County, MD. Embeddedness was not different enough to cause a shift in the macroinvertebrate community. Sculpin in both streams showed a pattern in which larger individuals were consuming larger prey items, and in turn more energy, in certain seasons. This pattern was evident in the summer, autumn, and winter for the 15% embedded streams and spring and autumn for the 35% embedded streams. Compositional analysis revealed that sculpin from the lower embeddedness level were consuming ephemeropterans regardless of their abundance, and sculpin from the higher sediment level preferred chironomids. A reduction in body condition was found at one of the 35% embedded sites, possibly due to consuming smaller, lower energy prey. It may be possible that increasing embeddedness levels are not changing the macroinvertebrate community but might restrict benthic fish access to valuable prey resources.

Use of multi‐state models to explore relationships between changes in body condition, habitat and survival of grizzly bears Ursus arctos horribilis

One of the principal goals of wildlife research and management is to understand and predict relationships between habitat quality, health of individuals and their ability to survive. Infrequent sampling, non‐random loss of individuals due to mortality and variation in capture susceptibility create potential biases with conventional analysis methods. To account for such sampling biases, we used a multi‐state analytical approach to assess relationships between habitat, health and survival of grizzly bears Ursus arctos horribilis over a 10‐year period along the east slopes of the Canadian Rockies in Alberta, Canada. We defined bear health states by body condition estimated from the relationship between weight and body length. We used a sequential model building process to first account for potential sampling biases, and then explored changes in body condition relative to habitat use and survival. Bears that used regenerating forest habitats (mostly due to forest harvesting) containing a diversity of age classes were more likely to see gains in their body condition, whereas bears that used older forests were more likely to see reductions in body condition. Survival rate was reduced most by road densities which in turn were positively correlated with regenerating forest habitat. Human activities which promote young regenerating forests, such as forest harvesting, therefore promotes improved health (increased body condition) in bears, but are offset by reductions in survival rates. Multi‐state analyses represents a robust analytical tool when dealing with complex relationships and sampling biases that arise from dynamic environments.