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For insects that overwinter as adults, winter food resources may affect subsequent spring reproduction and abundance. We tested if provision of food supplements to overwintering adult Hippodamia convergens (Guerin) increased energy reserves, winter survival, and spring reproduction. During 2015–2016, H. convergens adults were placed in field cages in December; adults in each cage received water, Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae), Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs, bee pollen, wheast protein, sugar, honey, or no food (control). In 2016–2017, treatments were reduced to sugar, bee pollen, A. pisum with E. kuehniella eggs, and no food (control). Adults were sampled to quantify weight, lipid, carbohydrate, and protein content. In 2015–2016, A. pisum and E. kuehniella eggs increased adult weight and protein content, but adult carbohydrate content was reduced by A. pisum and wheast protein treatments. Adults receiving honey and sugar supplementation had higher lipid and carbohydrate content relative to controls. The number of live individuals at the end of the experiment in March 2016 did not differ among treatments. In 2016–2017, winter prey supplements had the greatest effect on protein content, weight, and number of live adults recovered, whereas sugar supplementation increased lipid and carbohydrate content, and number of live adults recovered. Spring reproduction of surviving pairs was evaluated among treatments in March 2017. Prey supplementation in 2016–2017 increased the number of eggs laid and decreased preoviposition period, and food treatment did not affect fertility. Our results indicate that prey and sugar resources improve the overwintering success and spring reproduction of H. convergens. [ABSTRACT FROM AUTHOR]

The postfledging dependence period (PFDP) is a crucial stage in the development of altricial birds. This period is regulated by parental investment, in terms of food provisioning and protection, and the demands of young associated with their development and physical condition. We examine the relative role of parental investment, food provisioning, and offspring decisions on the PFDP regulation in the Spanish imperial eagle (Aquila adalberti) by comparing the PFDP timing among young from non-manipulated territories, food supplemented territories, and birds translocated by hacking methods in the absence of adults and with ad libitum food supply. We found that extra food homogenized the nutritional condition of young and reduced the length of the first stage of PFDP, which is related to flight development and thus dependent on body condition. However, hacked birds did not reduce this stage despite ad libitum food, likely due to the lack of parental stimulus to develop advanced flights. Although the presence of adults might accelerate young becoming independent, hacked birds did not extend significantly the whole PFDP and all birds eventually started dispersal. Thereby, the PFDP regulation was primarily under offspring control, and modulated secondarily by parental effects independently of food provisioning and laying date. The length of this period seems to be constrained mainly by the inherent benefits of early dispersal on ultimate fitness in accordance with ontogenic hypotheses. In addition, hacking was shown to be an effective translocation method when properly used, without negative drawbacks for young development during the PFDP. [ABSTRACT FROM AUTHOR]

Food resources and predation play important roles in determining small mammal population dynamics. These factors also can interact as individuals under predation pressure make trade-offs between access to food resources and exposure to predators. Fires consume food sources and reduce cover, which increases exposure to predators. For species that occur in areas with frequent fire, it is instructive to consider how all of these factors interact to affect populations of interest. We examined how supplemental feeding, mammalian predator exclusion, and prescribed fire affected survival, abundance, and reproduction of cotton mice (Peromyscus gossypinus) and oldfield mice (P. polionotus) in a longleaf pine ecosystem. Burning and predator exclusion interacted to affect survival of cotton mice; survival was similar in predator exclosures and controls in nonburning periods and in controls following prescribed burns but increased in exclosures following burns. Rates of transitions to reproductive states (which for females includes lactation or gravidity and for males, descent of testes) decreased in burn years but increased with the combination of feeding and predator exclusion. Supplemental feeding increased abundances. Among oldfield mice, survival and abundance were greater in predator exclusion areas than in controls. Supplemental feeding and the interaction of feeding and predator exclusion also increased abundances. During peak breeding seasons during which burning occurred rates of transitions to reproductive states declined to such an extent that reproductive transition rates in these seasons were lower than during nonpeak breeding seasons. [ABSTRACT FROM AUTHOR]

Food resources and predation can influence various aspects of the ecology of small mammals, including movement and space-use patterns. We used radiotelemetry to examine experimentally how supplemental feeding and mammalian predator exclusion affected size and exclusivity of hispid cotton rat (Sigmodon hispidus) home ranges. Supplemental feeding had no effect on home-range size, and exclusivity was not influenced by either treatment. However, predator exclusion was associated with increased home-range sizes, indicating a behavioral response to perceived predation risk. We suggest that this behavioral response reflects a trade-off between predation risk and space-use patterns. [ABSTRACT FROM AUTHOR]

The article presents a study which aims determine the mechanisms of the dawn singing of the Black-capped Chickadee. The study cites the two hypotheses, the "condition-dependent" and "social-dynamic" hypotheses on the collective behavior of a network of birds to give signals at the same time. Moreover, it shows that the Black-capped Chickadee's song output depends on body condition thus it contributes to individual differences.

Timing of breeding activities by birds has important fitness consequences, as deciding when to nest can affect nest success. For three breeding seasons, we provided supplemental food to Wrentits (Chamaea fasciata) inhabiting semiarid shrublands. We tested the effects of food supplementation on timing of initial egg laying, number of nests attempted, timing of fledging, and length of the breeding season. We also evaluated whether Wrentits timed nest initiation to avoid periods of greatest predation risk. Our study was conducted during a period of high interannual variation in precipitation. Supplemental food did not advance laying date in Wrentits. During a drought, even Wrentits given supplemental food delayed nesting, initiated fewer nesting attempts, fledged young earlier, and reduced the length of the breeding season. In a year of average rainfall, supplemental food allowed pairs to continue renesting late into the summer, after repeated nest losses from predation. Wrentits did not time nesting to avoid periods of greatest predation risk. In timing initial breeding, Wrentits appeared to be responding to climatic conditions and to indirect cues that predicted environmental conditions later in the breeding season rather than to food availability at the time of egg laying. [ABSTRACT FROM AUTHOR]

Considerable research supports the tenet that quantity and quality of food limit vertebrate populations. We evaluated predictions that increased availabilities of food and the essential amino acid methionine were related to population limitation of the hispid cotton rat (Sigmodon hispidus). Effects of supplemental food and methionine on density, survival, and reproductive parameters of wild cotton rats were assessed in north-central Oklahoma in 1998-1999. Twelve enclosed groups of 16 adult cotton rats each (S male, 8 female) were randomly assigned to either no supplementation (control), supplementation with a mixed ration that had methionine at slightly below maintenance levels (0.20%), or a methionine-enhanced mixed ration (1.20%). In general, densities of cotton rats were twice as high and were sustained longer with dietary supplementation, and methionine-supplemented populations maintained the highest densities. Treatment effects on survival depended on time of year, with higher survival in supplemented enclosures in October and November. Per capita recruitment was highest with methionine-enhanced food. Treatment effects on proportions of overall and female cotton rats in reproductive condition depended on sampling date, but males were most reproductively active with methionine supplementation. Methionine supplementation resulted in an earlier and longer reproductive season. Density- dependent and density-independent factors no doubt interplay to determine population dynamics of cotton rats, but our results suggest that methionine plays a role in the population dynamics of wild cotton rats, apparently by enhancing overall density, recruitment, and reproductive activity of males. [ABSTRACT FROM AUTHOR]

We examined effects of food and den site supplementation on population dynamics of Glaucomys sabrinus and Tamiasciurus douglasii in mature second-growth forests in British Columbia, Canada. We tested the hypothesis that populations of these squirrels were limited by abundance of food, not den sites. Populations were sampled intensively from June 1996 to March 1999 on controls and grids supplemented with food, food and nest boxes, and nest boxes. Analysis of variance revealed no differences in movement, abundance, recruitment, body mass of males, and percentage of males breeding among treatments for G. sabrinus or T. douglasii. Survival of G. sabrinus was not significantly different during pretreatment, but was significantly higher on grids supplemented with food during posttreatment. Occupancy rate of nest boxes in stands supplemented with nest boxes and food was 6- to 12-fold higher than in stands supplemented with nest boxes only. G. sabrinus occupied the majority of the nest boxes. We concluded that G. sabrinus used nest boxes readily but their populations were not limited by availability of den sites; availability of food appeared to have a significant effect on their populations. T. douglasii was not limited by availability of food or den sites during our study. [ABSTRACT FROM AUTHOR]