Higher Body Condition Index Research Articles

Biology and population dynamics of the black-flanked rock-wallaby (Petrogale lateralis lateralis) in the central wheatbelt of Western Australia

Through a mark–recapture study, we explored aspects of the biology and population dynamics in the largest known population of the black-flanked rock-wallaby (Petrogale lateralis lateralis) at Mt Caroline Nature Reserve, in the Western Australian wheatbelt in 2007–10. The body condition index of males and females varied significantly over time but fluctuated similarly for both sexes. Males and females followed a pattern of best condition in early summer, declining through autumn and reaching their poorest condition in early spring. Body condition was closely related to rainfall in the period ~3–6 months before trapping sessions. Births occurred throughout the year with two reproductive peaks, in autumn and late winter/spring. Reproductive rates averaged over 90% annually, except in 2007 when they averaged 76%. Significantly fewer females bred during 2007, and those females were in poorer body condition. Females with a higher body condition index were more likely to reproduce (P = 0.003) but body condition did not influence the sex of offspring. The sex ratio of offspring did not differ significantly from parity and did not support either the Trivers–Willard or local resource competition hypotheses. This information should help to predict population trends and develop appropriate conservation strategies for this threatened species.

Body weight provides insights into the feeding strategy of swarming bats.

Temperate bat species that hibernate in underground sites are known to visit hibernacula in late summer where they perform an activity known as swarming. We analysed trends in body mass-to-forearm ratio - the body condition index (BCI) - to investigate whether bats arrive at swarming sites following intensive nocturnal feeding. In a two-year study, Myotis daubentonii , M. brandtii and M. dasycneme were captured by mist-net at one swarming site from late July until early October. In late summer, the BCIs of captured males, females and subadult bats were positively correlated to the time of their capture during the night. In September, adult bats had higher BCIs than in late summer and the BCI did not increase during the night. For subadult M. daubentonii , the BCI was positively correlated to the time of capture in early autumn. Our results indicate that in late summer bats feed intensively during the first hours of the night before visiting swarming sites. In early autumn, subadult bats may go on feeding to complete fat accumulation.

Is sexual body shape dimorphism consistent in aquatic and terrestrial chelonians?

Comparisons between aquatic and terrestrial species provide an opportunity to examine how sex-specific adaptations interact with the environment to influence body shape. In terrestrial female tortoises, selection for fecundity favors the development of a large internal abdominal cavity to accommodate the clutch; in conspecific males, sexual selection favors mobility with large openings in the shell. To examine to what extent such trends apply in aquatic chelonians we compared the body shape of males and females of two aquatic turtles ( Chelodina colliei and Mauremys leprosa). In both species, females were larger than males. When controlled for body size, females exhibited a greater relative internal volume and a higher body condition index than males; both traits potentially correlate positively with fecundity. Males were more streamlined (hydrodynamic), and exhibited larger openings in the shell providing more space to move their longer limbs; such traits probably improve mobility and copulation ability (the males chase and grab the female for copulation). Overall, although the specific constraints imposed by terrestrial and aquatic locomotion shape the morphology of chelonians differently (aquatic turtles were flatter, hence more hydrodynamic than terrestrial tortoises), the direction for sexual shape dimorphism remained unaffected. Our main conclusion is that the direction of sexual shape dimorphism is probably more consistent than sexual size dimorphism in the animal kingdom.

Patterns of variation of serum oxidative stress markers in two seabird species

Variation in oxidative stress markers in natural populations may provide a useful background for understanding variation in life history strategies. In this study, we seek to evaluate patterns of variation in levels of reactive oxygen metabolites (markers of oxidative damage), serum antioxidant capacity, and serum concentration of thiols (antioxidants endogenously synthesized) in nestling and breeding blue petrels (Halobaena caerulea) and in breeding Antarctic prions (Pachyptila desolata). Male and female prions and nestling petrels did not differ in any of the oxidative stress markers. The serum antioxidant capacity positively correlated with the sample time in nestling blue petrels. Breeding petrels with higher body condition index had higher serum antioxidant capacity and circulating thiols. Finally, both seabird species showed lower levels of reactive oxygen metabolites and higher levels of serum antioxidant capacity than previously studied bird species.

Patterns of variation of serum oxidative stress markers in two seabird species

Variation in oxidative stress markers in natural populations may provide a useful background for understanding variation in life history strategies. In this study, we seek to evaluate patterns of variation in levels of reactive oxygen metabolites (markers of oxidative damage), serum antioxidant capacity, and serum concentration of thiols (antioxidants endogenously synthesized) in nestling and breeding blue petrels (Halobaena caerulea) and in breeding Antarctic prions (Pachyptila desolata). Male and female prions and nestling petrels did not differ in any of the oxidative stress markers. The serum antioxidant capacity positively correlated with the sample time in nestling blue petrels. Breeding petrels with higher body condition index had higher serum antioxidant capacity and circulating thiols. Finally, both seabird species showed lower levels of reactive oxygen metabolites and higher levels of serum antioxidant capacity than previously studied bird species.

Sex-Related Mortality of White Ibis(Eudocimus albus)Nestlings During a Starvation Event

Abstract During a time of food stress, we observed sex-biased mortality during the nestling stage in a sexually size dimorphic species of wading bird, the White Ibis (Eudocimus albus). Over four days spread out over a week, we captured a total of 180 25–32 d old White Ibis nestlings from a colony of several thousand breeding pairs. On sequential capture dates we caught significantly fewer females than males. Through this time period male nestlings had higher body condition indices (mass/tarsus) than females, though the rates at which male and female body condition increased over the week were not significantly different. Several sources of evidence suggest that our sampling was not sex-biased and was reflective of actual changes in abundance of males and females. These data indicate that despite the greater caloric requirements of males, their larger size may have conferred a competitive advantage over female siblings in obtaining food from parents during a time of food shortage.

Differences in Primary Molt and Biometrics between Adult and Second-year Black-headed Gulls in Puck Bay (Southern Baltic)

Abstract Black-headed Gulls (Larus ridibundus) were caught on the southern Baltic coast during early phase of their autumn migration between 27 July and 9 August from 1992 to 1995. Due to involvement in breeding, adult Black-headed Gull started primary replacement later than second-year birds, but their molt was slightly faster during the studied two-week period. This suggests that the difference in primary molt score between the age classes may decrease toward the end of the molt period. There were no differences in primary molt between sexes. Adults had larger hole in wing area and they had higher body condition index than second-year birds. This might reflect higher cost of flight of adults due to their lower aerodynamic efficiency of the wing and their tendency to buffer themselves against increased energetic stress. Second-year Black-headed Gulls migrate for longer distances farther than adults on average and this might be a reason of their slower rate of primary replacement.

Male Reproductive Success and Intrasexual Selection in the Common Lizard Determined by DNA-microsatellites

The common lizard (Lacerta vivipara) is a small, nonterritorial, live-bearing lacertid that is sexually dimorphic in several morphological traits (e.g., tail length, snout–vent length, head size). Using microsatellites, we examined paternity in a wild population and investigated whether sexual dimorphism could be the result of intra- or intersexual selection. We found multiple paternity in 65.4% of 26 clutches. There was no evidence of assortative mating. Successfully reproducing males were larger and heavier and had longer tail regenerates or intact tails compared to those that did not reproduce. Tail length and body condition of males were related to the number of offspring sired. However, we found no evidence that head width was related to male reproductive success. We conclude that (1) males with higher body condition index might be more successful in male-male interactions or might be able to search more effectively for females, (2) sex divergence in relative tail length in common lizards reflects the action of sexual selection for male reproductive success, and (3) intersexual dietary divergence could be an alternative hypothesis for head size difference between sexes rather than intrasexual selection.

Effects of inter- and intraspecific competition on growth and development of Bufo viridis and Bufo bufo tadpoles

Competition between the common toad Bufo bufo (L.) and the green toad Bufo viridis Laurenti was studied in an experimental design. Mixed and single-species groups of 40 larvae were reared in plastic tanks (water volume 411). Growth parameters such as body length, total length, body mass and developmental stage according to Gosner (1960) were measured weekly until metamorphic climax and analyzed by regression analysis. Body condition index was calculated. Tadpoles of B. bufo reached metamorphosis at the same time in mixed and single-species treatments. Larvae and toadlets were insignificantly larger in single-species groups, weighed more and had a higher body condition index than in mixed species designs. In B. viridis the larval period was six days shorter in mixed groups; tadpoles and toadlets were smaller but had a higher body condition index than in the single-species treatment. These results indicate high intraspecific competition in B. viridis and competitive inferiority of B. bufo to B. viridis under the experimental conditions.

BODY CONDITION AND MATE CHOICE IN TETRAGNATHA ELONGATA (ARANEAE, TETRAGNATHIDAE)

The mate preference characteristics of adult Tetragnatha elongata were assessed with respect to measures of female mass, linear size (length), and condition (mass scaled by length: body condition). Males preferred longer, heavier females and females with higher body condition indices. When mass is partially controlled, males still preferred females of higher body condition, but reversed their preference for length and chose smaller females. We present evidence that female body condition and mass are associated with the volume of her egg load and the proximity of oviposition, whereas female body length is not associated with either. Females displayed no clear preference among males for mass or linear size, but were reluctant to mate in female-choice trials. The small sample size obtained may have obscured the detection of female mate preferences if they exist. This may be the first evidence that mate choice is influenced by body condition rather than mass or linear size among spiders.

Body condition, growth rates and diet of Skylark Alauda arvensis nestlings on lowland farmland

Factors affecting the diet, body condition and growth rates of Skylark chicks were assessed to examine their relationship to their agricultural environment during a critical period in the life cycle of this rapidly declining species. Rainfall explained the greatest amount of variation in body condition and growth rates and had a negative effect on both. Body condition indices were a good predictor of the likelihood of future partial brood loss to starvation. Low body condition in grass fields was related to a low diversity in the diet. Chicks fed insect larvae had higher body condition indices than those not fed larvae. Larger broods tended to have higher growth rates than smaller ones, whereas smaller broods tended to have higher body condition indices. Natural brood size reduction through the non‐hatching of eggs resulted in higher body condition indices than were found in nests with the same number of chicks where all eggs hatched, this effect being independent of absolute brood size. There was no significant difference between crop types in the distance adult birds flew to forage for food for nestlings and foraging crop destination had no effect on chick development. Differences between crop types in chick diet could be related to the documented effects of pesticides on different prey species. We suggest that recent agricultural changes have affected diet and possibly body condition, but that these effects are unlikely to have been an important factor in recent population declines.

Mate Switching in a Non‐monogamous Species? The Case of the Common Quail(Coturnix coturnix)

AbstractWe investigated the occutrence of mate switching in the common quail, a non‐monogamous species with a temporal pair bond but without either male parental care or territoriality. The study was carried out throughout the breeding seasons of 1993–95 in Mas Esplugues (Catalonia, Spain) by monitoring 28 radio‐tagged couples and 17 radio‐tagged unpaired males. Agonistic interactions between males inside funnel traps containing a female were also recorded. Mate switching within the laying period occurred in 72% of the females, and new partners always had a higher body condition index than old partners. Agonistic interactions inside the funnel traps also showed that successful males had a better body condition index than losers. These results, along with the observed mate‐guarding behaviour of females by their partners throughout the laying period, a highly male‐biased sex ratio (five males per female), the lack of territoriality of males and the expected difficulties which unmated males experience in finding pairs, suggest that mate switching is not induced by paired males. Moreover, the constant inflow of new males observed throughout the fertile period of the female and the low costs stemming from mate change strongly support the idea that it is paired females who induce mate switching, in order to improve their fitness by mating with the best quality male available at every moment of their fertile period.

Ascaridoid Nematodes from the Stomach of Harp Seals, Phoca groenlandica, from Newfoundland and Labrador

Stomachs of 488 harp seals, Phoca groenlandica, collected off Newfoundland and Labrador during 1984–88, contained four species of ascaridoid nematodes. Seals had high prevalences and abundances of Contracaecum osculatum B and Phocascaris sp. but were rarely infected with Anisakis simplex B or Pseudoterranova decipiens B (sealworm). Nematode abundance increased with age, and distribution of each species among seals was highly aggregated. Gastric lesions, often associated with clusters of nematodes, occurred in 13.8% of 405 seals. Female seals with large numbers of nematodes had a higher body condition index (sculp weight) than lightly infected females. Overall sex ratios of C. osculatum B and Phocascaris sp. were biased toward females, but sex ratios of adult nematodes among individual seals were heterogeneous. Most nematodes recovered were third- or fourth-stage larvae; adults of C. osculatum B and Phocascaris sp. were also common, but no mature females of A. simplex B or P. decipiens B were found. Harp seals are probably unimportant in the transmission of A. simplex but may be partly responsible for sealworm found in fish stocks off Newfoundland and Labrador. More information on other pinniped species is needed to assess more precisely the relative importance of harp seals in sealworm transmission.