Avian prey-dropping behavior. I. The effects of prey characteristics and prey loss

Numerous species of birds break hard-shelled prey items by droppingthem from a height. This intriguing prey-extraction method providesan excellent opportunity for studying foraging behavior becausea single, easily measurable quantity—height of drop—maybe influenced by a wide variety of identifiable characteristicsof the prey (e.g., breakability, weight) and social environment(e.g., alone or in the presence of kleptoparasites). Using adynamic, state variable modeling approach, this paper presentsthe first theoretical framework for avian prey-dropping systemsthat incorporates the diversity of prey characteristics andsocial situations. The model yielded a series of qualitativepredictions about prey-dropping behavior that can be testedreadily in any prey-dropping system. In particular, the results indicatedthat quantitative and qualitative differences in item breakability andpotential kleptoparasitism should have a significant effecton the height and pattern of prey dropping.     

An Assessment of Diversity,Inclusion, and Health Equity Training in Endocrinology Fellowship Programs in the United States

ContextThe Accreditation Council for Graduate Medical Education has instituted common program requirements related to diversity, equity, and inclusion (DEI) for postgraduate trainees in the United States; however, the extent to which DEI training is being incorporated across endocrinology fellowship programs is unknown.ObjectivesTo describe the sociodemographic representation and DEI training experiences within endocrinology fellowship programs.Design, setting, and participantsNational cross-sectional survey study of fellows and fellowship program leaders in the United States whose fellowships were members of the Association of Program Directors in Endocrinology and Metabolism.Main outcome measures(1) Demographics of fellows and program leaders and (2) programs’ experience, confidence, and interest in formal DEI training.ResultsA total of 108 and 106 fellow and faculty responded to the survey, respectively. The majority of fellows and faculty are female. Less than 3% of fellows and 3.7% of faculty identify as Black. More than 90% of fellows/faculty are heterosexual and no respondents identified as transgender/nonbinary; however, 5% and 2% of all respondents preferred not to disclose their sexual orientation and gender identity, respectively. While 85% of faculty received institutional diversity and inclusion training, 67.6% of fellows did. Fellows are more likely to have received training in health equity than program leaders. Both fellows and program leaders express a high interest in health equity curriculum.ConclusionsWithin the diversity of endocrinology training programs, Black physicians are underrepresented in medicine, which persists in endocrinology fellowships. Fellowship programs express enthusiasm for national diversity and health equity curricula, with the majority of programs reporting institutional DEI training.     

Potential and realized reproduction by different worker castes in queen-less and queen-right colonies of <Emphasis Type="Italic">Pogonomyrmex badius</Emphasis>

Workers of the Florida harvester ant (Pogonomyrmex badius), the only North American Pogonomyrmex with a polymorphic worker caste, produce males when colonies are orphaned. In this study,we assessed the reproductive potential of workers of each caste group, minors and majors, in the presence and absence of the queen, and tested whether males produced in natural queen-right colonies are derived from workers. Worker size was positively correlated with ovariole number such that major workers had approximately double the number of ovarioles as minor workers. The number of vitellogenic oocytes, a measure of reproductive potential, was greater in major compared to minor workers and increased in both worker castes when queens were removed. Major workers have greater reproductive potential than minors although they represent a minority within the colony (~5% of workers are majors). Worker produced eggs were visible in colonies 28 – 35 days after queen removal. This time lag, from queen removal to egg production, is similar to other ants and bees. Though workers are capable of producing viable eggs, we found no evidence that they do so in queen-right colonies, suggesting that worker reproduction is controlled via some social mechanism (self restraint, policing, or inhibition). This result supports predictions of kin selection theory – that due to multiple mating by the queen workers are more related to queen-produced males than most worker-produced males and should thus favor reproduction by the queen and inhibit reproduction by other workers. Received 25 January 2007; revised 1 May 2007; accepted 21 May 2007.     

Use of membrane filters for soil algal bioassays

A culture technique for eucaryotic and procaryotic soil algae involving the use of membrane filters superimposed on the surface of inorganic nutrient agar is described. Nostoc commune grew exponentially when cultured in this manner. No significant differences in biomass production or nitrogenase activity were detected among culture subsets within replicate experiments run under standard conditions. Estimates of daily growth rates (0.340), culture doubling time (48.9 h), and nitrogenase activity (14.54 nM C₂H₂ reduced μg⁻¹ chl a h⁻¹) were consistent with laboratory and field estimates reported for several planktonic species of Anabaena and strains of Nostoc commune isolated from diverse terrestrial habitats. Therefore, the filter-culture technique is an alternative which may be superior to traditional liquid culture methodology for studies involving certain soil procaryotic and eucaryotic algae.     

Physiological Costs of Mate Guarding in the Japanese Beetle (Popillia japonica Newman)

Males of many insects directly defend their mates from rival males (i.e. mate guard) as a way to avoid sperm competition and thus increase their reproductive success. However, mate guarding may have associated costs for these males. We examined costs of mate guarding in Japanese beetles (Popillia japonica), a pest species which exhibits post‐copulatory mate guarding during which the guarding male cannot feed. In this species, food provides both energy and water for thermoregulation. Consequently, we focused on possible thermoregulatory and energetic costs of their mate guarding. In a field study, we found that guarding males had significantly higher thoracic temperatures than non‐guarding males, indicating a difference in their ability and/or need to thermoregulate. Paired males had significantly lower water levels than single males in the morning and evening, but not in the afternoon. In the laboratory, we found that mate‐guarding duration was significantly shorter at higher ambient temperature than at lower temperature, and males that had been starved guarded for less time than males that had not been starved. Our results suggest that because guarding males are unable to feed, they suffer energetic and thermoregulatory costs that appear to limit the amount of time that they can guard a female.     

Camera traps reveal an apparent mutualism between a common mesocarnivore and an endangered ungulate

Camera traps are commonly used to study mammal ecology and they occasionally capture previously undocumented species interactions. The key deer (Odocoileus virginianus clavium) is an endangered endemic subspecies of the Florida Keys, where it exists with few predators. We obtained a camera trap sequence of 80 photos in which a key deer interacted with two northern raccoons (Procyon lotor). One of the raccoons groomed the deer’s face for ∼1 min. This interaction is peculiar and appears mutualistic because the deer was not concerned and willingly remained still throughout the physical contact. Although mutualistic relationships between deer and birds are common, we are unaware of any previously documented mesocarnivore-deer mutualisms. Key deer have evolved in the absence of mammalian predators and we hypothesize that they exhibit reduced vigilance or concern when encountering other species because of predator naivety. Key deer and raccoons are commonly associated with humans and urbanization and an alternative hypothesis is that the interactions are a consequence of heightened deer density, causing a greater probability of sustained interactions with the common mesocarnivores.     

Studies on the bacterial flora of tubificid worms

Study of the bacterial flora of the gut of the turbificid worms has shown that u. v. starilization, serial culturing, and standard bacterial identification procedures can be employed successfully. Eighteen species of bacteria were isolated and identified from the gut of tubificid worms. Eleven of the species were Gram negative which may be reflected in their possible association with chlorogonal cell metabolism in tubificid worms. Of the eighteen species identified our genera and two species are on a similar list produced by Brinkhurst & Chua in an earlier study (1969) of worms from the Great Lakes. None of the organisms identified were other than common to fresh water, organic decay processes or animal digestive systems. Their role in tubificid nutrition is now under study.Supported by a grant from the Council on Faculty Research, Eastern Illinois University.