scholarly journals Experimental food supplementation increases reproductive effort in an antbird in subtropical Brazilian Atlantic Forest fragments

2014 ◽  
Author(s):  
James J Roper ◽  
André M. X. Lima ◽  
Angélica M. K. Uejima
Keyword(s):  
Food Availability ◽  
Reproductive Effort ◽  
Fragment Size ◽  
Food Limitation ◽  
Survival Rates ◽  
Food Supplementation ◽  
Fragmented Landscape ◽  
Forest Fragments ◽  
Daily Nest Survival ◽  
Nesting Patterns

Food limitation may interact with nest predation and influence nesting patterns, such as breeding season length and renesting intervals. If so, reproductive effort should change with food availability. Thus, when food is limited, birds should have fewer attempts and shorter seasons than when food is not limiting. Here we experimentally test that increased food availability results in increased reproductive effort in a fragmented landscape in the Variable Antshrike (Thamnophilus caerulescens) in southern Brazil. We followed nesting pairs in five natural fragments (4, 23, 24, 112, 214 ha) in which food was supplemented for half of those pairs, beginning with the first nest. Nest success in the largest (214 ha) fragment was 59%, compared to 5% in the 112 ha fragment and no nest was successful in the smallest (24 ha) fragment. Birds were seen, but evidence of nesting was never found in the two smallest fragments. Pairs with supplemented food were more likely to increase clutch size from two to three eggs, tended to renest sooner (20 d on average) than control pairs. Also, fragment size interacted with breeding and pairs in the largest fragment had greater daily nest survival rates, and so nests tended to last longer, and so these pairs had fewer nesting attempts than those in the 112 ha fragment while more than those in the smallest fragment with nesting (24 ha). Clearly, pairs increased their reproductive effort when food was supplemented in comparison to control pairs and fragment size seems to influence both predation risk and food abundance.

scholarly journals Experimental food supplementation increases reproductive effort in an antbird in subtropical Brazilian Atlantic Forest fragments

2014 ◽  
Author(s):  
James J Roper ◽  
André M. X. Lima ◽  
Angélica M. K. Uejima
Keyword(s):  
Food Availability ◽  
Reproductive Effort ◽  
Fragment Size ◽  
Food Limitation ◽  
Survival Rates ◽  
Food Supplementation ◽  
Fragmented Landscape ◽  
Forest Fragments ◽  
Daily Nest Survival ◽  
Nesting Patterns

Food limitation may interact with nest predation and influence nesting patterns, such as breeding season length and renesting intervals. If so, reproductive effort should change with food availability. Thus, when food is limited, birds should have fewer attempts and shorter seasons than when food is not limiting. Here we experimentally test that increased food availability results in increased reproductive effort in a fragmented landscape in the Variable Antshrike (Thamnophilus caerulescens) in southern Brazil. We followed nesting pairs in five natural fragments (4, 23, 24, 112, 214 ha) in which food was supplemented for half of those pairs, beginning with the first nest. Nest success in the largest (214 ha) fragment was 59%, compared to 5% in the 112 ha fragment and no nest was successful in the smallest (24 ha) fragment. Birds were seen, but evidence of nesting was never found in the two smallest fragments. Pairs with supplemented food were more likely to increase clutch size from two to three eggs, tended to renest sooner (20 d on average) than control pairs. Also, fragment size interacted with breeding and pairs in the largest fragment had greater daily nest survival rates, and so nests tended to last longer, and so these pairs had fewer nesting attempts than those in the 112 ha fragment while more than those in the smallest fragment with nesting (24 ha). Clearly, pairs increased their reproductive effort when food was supplemented in comparison to control pairs and fragment size seems to influence both predation risk and food abundance.

scholarly journals Experimental food supplementation increases reproductive effort in the Variable Antshrike in subtropical Brazil

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5898 ◽  
Author(s):  
James J. Roper ◽  
André M.X. Lima ◽  
Angélica M.K. Uejima
Keyword(s):  
Breeding Season ◽  
Food Availability ◽  
Reproductive Effort ◽  
Fragment Size ◽  
Food Limitation ◽  
Food Supplementation ◽  
Fragmented Landscape ◽  
Forest Fragments ◽  
Season Length ◽  
Fragmented Habitat

Food limitation may interact with nest predation and influence nesting patterns, such as breeding season length and renesting intervals. If so, reproductive effort should change with food availability. Thus, when food is limited, birds should have fewer attempts and shorter seasons than when food is not limiting. Here we experimentally test that increased food availability results in increased reproductive effort in a fragmented landscape in the Variable Antshrike (Thamnophilus caerulescens) in southern Brazil. We followed nesting pairs in a naturally fragmented habitat and experimentally supplemented food for half of those pairs. Birds were seen, but evidence of nesting was never found in two small fragments, even though these fragments were larger than individual territories. Pairs with supplemented food were more likely to increase clutch size from two to three eggs and tended to renest sooner (20 d on average) than control pairs. Also, fragment size was associated with breeding patterns, although fragment replicates were unavailable. Nest duration, nest success and breeding season length were all greater, while renesting intervals were shorter, in the largest fragments. Simulations showed that only the largest fragments were able to have a net production of young. Food availability clearly influenced reproductive effort and as a consequence, because of the interaction with predation risk, forest fragments of varying sizes will have complex reproductive dynamics.

scholarly journals Food limitation constrains host immune responses to nematode infections

2016 ◽  
Vol 12 (9) ◽  
pp. 20160471 ◽  
Author(s):  
Kristian M. Forbes ◽  
Tapio Mappes ◽  
Tarja Sironen ◽  
Tomas Strandin ◽  
Peter Stuart ◽  
...  
Keyword(s):  
Immune Responses ◽  
Food Availability ◽  
Food Limitation ◽  
Finite Energy ◽  
Innate Immune ◽  
Food Supplementation ◽  
Boreal Winter ◽  
Intestinal Nematode ◽  
Trade Offs ◽  
Parasite Infections

Trade-offs in the allocation of finite-energy resources among immunological defences and other physiological processes are believed to influence infection risk and disease severity in food-limited wildlife populations. However, this prediction has received little experimental investigation. Here we test the hypothesis that food limitation impairs the ability of wild field voles ( Microtus agrestis ) to mount an immune response against parasite infections. We conducted a replicated experiment on vole populations maintained in large outdoor enclosures during boreal winter, using food supplementation and anthelmintic treatment of intestinal nematodes. Innate immune responses against intestinal parasite infections were compared between food-supplemented and non-supplemented voles. Voles with high food availability mounted stronger immune responses against intestinal nematode infections than food-limited voles. No food effects were seen in immune responses to intracellular coccidian parasites, possibly owing to their ability to avoid activation of innate immune pathways. Our findings demonstrate that food availability constrains vole immune responses against nematode infections, and support the concept that spatio-temporal heterogeneity in food availability creates variation in infectious disease susceptibility.

scholarly journals Reproductive success of Trypoxylon (Trypargilum) lactitarse (Hymenoptera: Crabronidae) in a fragmented landscape

2020 ◽  
Vol 110 ◽  
Author(s):  
Grayce Kelly Costa Oliveira ◽  
Marcos Antonio da Silva Elias ◽  
Leonardo Lima Bergamini ◽  
Edivani Villaron Franceschinelli
Keyword(s):  
Reproductive Success ◽  
Fragment Size ◽  
Larval Survival ◽  
Fragmented Landscape ◽  
Forest Fragments ◽  
Wasp Species ◽  
Local Species Richness ◽  
Trap Nests ◽  
The Difference ◽  
Number Of Cells

ABSTRACT Fragmentation of natural vegetation often implies a reduction in local species richness and abundance. The resources used by bees and wasps for feeding and nesting are distributed quite irregularly in fragmented environments, which influences their foraging behavior, occurrence patterns and reproductive success. The objective of the present work was to determine if the size of native vegetation remnants influences the reproductive success of the solitary wasp species Trypoxylon (Trypargilum) lactitarse Saussure, 1867. Trap-nests were established along the edges of forest fragments of different sizes located in municipalities in the central region of the state of Goiás, Brazil. The nests were used to quantify nesting rate, number of cells with larvae, survival of larvae, proportion of nests attacked by parasitoids, and size of hatched adults. The foundation rate of trap-nests was greater in large fragments, whereas the mean number of cells per nest, parasitoidism rate, larval survival and sex ratios, and size of hatched adults did not differ between large and small fragments. Therefore, it appears that fragment size influences the survival or permanence of adults more so than it does that of the larvae in the studied fragments. There are two possible explanations for the difference in the foundation rate: 1) each female founds, in average, the same number of nests in small and large fragments, but the number of females is lower in the smaller fragments; 2) females have the capacity to provision several nests, but in the larger areas each female founds more nests than in smaller areas. However, it is necessary future studies to differentiate these two hypotheses.

scholarly journals Small mammal glucocorticoid concentrations vary with forest fragment size, trap type, and mammal taxa in the Interior Atlantic Forest

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sarah A. Boyle ◽  
Noé U. de la Sancha ◽  
Pastor Pérez ◽  
David Kabelik
Keyword(s):  
Atlantic Forest ◽  
Small Mammals ◽  
Acute Stress ◽  
Physiological Stress ◽  
Fragment Size ◽  
Hair Shaft ◽  
Forest Fragments ◽  
Forest Fragment ◽  
Trapping Methods ◽  
Free Ranging

AbstractSpecies that live in degraded habitats often show signs of physiological stress. Glucocorticoid hormones (e.g., corticosterone and cortisol) are often assessed as a proxy of the extent of physiological stress an animal has experienced. Our goal was to quantify glucocorticoids in free-ranging small mammals in fragments of Interior Atlantic Forest. We extracted glucocorticoids from fur samples of 106 small mammals (rodent genera Akodon and Oligoryzomys, and marsupial genera Gracilinanus and Marmosa) from six forest fragments (2–1200 ha) in the Reserva Natural Tapytá, Caazapá Department, Paraguay. To our knowledge, this is the first publication of corticosterone and cortisol levels for three of the four sampled genera (Akodon, Oligoryzomys, and Marmosa) in this forest system. We discovered three notable results. First, as predicted, glucocorticoid levels were higher in individuals living withing small forest fragments. Second, animals captured live using restraint trapping methods (Sherman traps) had higher glucocorticoid levels than those animals captured using kill traps (Victor traps), suggesting that hair glucocorticoid measures can reflect acute stress levels in addition to long-term glucocorticoid incorporation. These acute levels are likely due to urinary steroids diffusing into the hair shaft. This finding raises a concern about the use of certain trapping techniques in association with fur hormone analysis. Finally, as expected, we also detected genus-specific differences in glucocorticoid levels, as well as cortisol/corticosterone ratios.

Food supplementation and abundance estimation in the white-footed mouse

2006 ◽  
Vol 84 (8) ◽  
pp. 1210-1215 ◽  
Author(s):  
Pei-Jen L. Shaner
Keyword(s):  
Population Dynamics ◽  
Food Availability ◽  
Robust Design ◽  
Meta Analysis ◽  
Design Model ◽  
Food Supplementation ◽  
Abundance Estimates ◽  
Abundance Indices ◽  
Consumer Population ◽  
White Footed Mouse

Food availability often drives consumer population dynamics. However, food availability may also influence capture probability, which if not accounted for may create bias in estimating consumer abundance and confound the effects of food availability on consumer population dynamics. This study compared two commonly used abundance indices (minimum number alive (MNA) and number of animals captured per night per grid) with an abundance estimator based on robust design model as applied to the white-footed mouse ( Peromyscus leucopus (Rafinesque, 1818)) in food supplementation experiments. MNA consistently generated abundance estimates similar to the robust design model, regardless of food supplementation. The number of animals captured per night per grid, however, consistently generated lower abundance estimates compared with MNA and the robust design model. Nevertheless, the correlations between abundance estimates from MNA, number of animals captured, and robust design model were not influenced by food supplementation. This study demonstrated that food supplementation is not likely to create bias among these different measures of abundance. Therefore, there is a great potential for conducting meta-analysis of food supplementation effect on consumer population dynamics (particularly in small mammals) across studies using different abundance indices and estimators.

The importance of recruitment patterns versus reproductive output in the persistence of a short-range endemic shrub in a highly fragmented landscape of south-western Australia

2012 ◽  
Vol 60 (7) ◽  
pp. 643 ◽  
Author(s):  
Neil Gibson ◽  
Colin Yates ◽  
Margaret Byrne ◽  
Margaret Langley ◽  
Rujiporn Thavornkanlapachai
Keyword(s):  
Short Range ◽  
Reproductive Output ◽  
Fruit Set ◽  
Seedling Recruitment ◽  
Fragment Size ◽  
Fragmented Landscape ◽  
Recruitment Failure ◽  
Degree Of Isolation ◽  
Number Of Seeds ◽  
Significant Mortality

Calothamnus quadrifidus subsp. teretifolius A.S.George & N.Gibson is a short-range endemic shrub whose habitat has been greatly reduced by clearing for agriculture. Reproductive output was high in all populations sampled, although there were large differences among populations in fruit set, the number of seeds per fruit and seed germination. These traits showed no relationship to population size, degree of isolation, or fragment size, which contrasts strongly with the patterns found in a widespread congener. Demographic studies in remnants with an intact understorey showed stable adult populations with continuous seedling recruitment. In contrast, there was consistent widespread failure of seedling and juvenile recruitment in degraded roadside remnants that also showed significant mortality of reproductive adults. In these degraded remnants, recruitment failure appears to be the primary cause of species decline.

Effect of Prey Density and Prey Size on Growth and Survival of Juvenile Walleye (Stizostedion vitreum vitreum)

1989 ◽  
Vol 46 (8) ◽  
pp. 1323-1328 ◽  
Author(s):  
Michael G. Fox
Keyword(s):  
Prey Density ◽  
Prey Availability ◽  
Food Limitation ◽  
Survival Rates ◽  
Stizostedion Vitreum ◽  
Growth And Survival ◽  
First Feeding ◽  
Length Increase ◽  
Prey Length ◽  
Chironomid Biomass

I investigated the influence of food availability on growth and survival of walleye (Stizostedion vitreum vitreum) fry stocked in six fertilized experimental ponds (density 40 fish∙m−3) and reared for 8 wk. Walleye fed largely on chironomid larvae and cyclopoid copepods in weeks 1 and 2, and chironomids thereafter. Prey choice and consumption were strongly influenced by chironomid biomass in the benthos, and to a lesser extent by zoo-plankton density. Weekly length increase of the populations and mean length in week 7 were significantly correlated with chironomid benthic biomass and mean prey length. Chironomid biomass and density of large zoo-plankton together explained 56% of the variation in the weekly population growth rate. Despite obvious food limitation in the second half of the experiment, pond survival rate was not significantly correlated with mean prey density, mean stomach fullness, or percentage of fish with empty stomachs. The results indicate that juvenile walleye growth can be regulated by the density and size of available prey. Prey availability apparently does not regulate short term juvenile walleye survival rates after the period around first feeding.

Forest corridors facilitate movement of tropical forest birds after experimental translocations in a fragmented Neotropical landscape in Mexico

2011 ◽  
Vol 27 (5) ◽  
pp. 547-556 ◽  
Author(s):  
Ana Ibarra-Macias ◽  
W. Douglas Robinson ◽  
Michael S. Gaines
Keyword(s):  
Forest Birds ◽  
Fragmented Landscape ◽  
Forest Fragments ◽  
Forest Dependence ◽  
Capture Site ◽  
Forest Corridors ◽  
Capture Recapture ◽  
Species Characteristics ◽  
Species Groups ◽  
Positive Effect

Abstract:We evaluated effects of corridors between forest fragments surrounded by pastures in tropical Mexico. We used experimental translocations and capture–recapture data to measure the proportion of birds returning and time to return after translocation between connected and unconnected patches (five replicates for each treatment). Depending on each species’ degree of forest dependence (forest-restricted and forest-unrestricted species), we assigned birds to two groups to evaluate influence of species characteristics on effects of corridors on movement. Birds translocated between connected patches (n = 75) were seven times more likely to be recaptured in their original capture site when compared with birds translocated between unconnected patches (n = 109). Effects differed among the two species groups. In the presence of corridors, 46% of forest-unrestricted birds returned to the capture site while only 5% returned between unconnected patches. Forest-restricted birds showed similar results, but were only twice as likely to return to a connected capture site. Birds translocated between unconnected patches took longer to return than birds translocated between connected patches. The strong positive effect of corridors on movement, even for forest-unrestricted species, suggests that forested corridors facilitate bird movement and help maintain connectivity even in this highly fragmented landscape.

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