scholarly journals Maternal glucocorticoid levels during incubation predict breeding success, but not reproductive investment, in a free-ranging bird

2019 ◽  
Author(s):  
Devin Fischer ◽  
Robby R. Marrotte ◽  
Eunice H. Chin ◽  
Smolly Coulson ◽  
Gary Burness
Keyword(s):  
Breeding Success ◽  
Positive Relationship ◽  
Negative Relationship ◽  
Reproductive Investment ◽  
Egg Laying ◽  
Tree Swallows ◽  
Female Tree ◽  
Adaptation Hypothesis ◽  
Breeding Seasons ◽  
Free Ranging

ABSTRACTThe hormone corticosterone (CORT)) has been hypothesized to be linked with fitness, but the directionality of the relationship is unclear. The “CORT-fitness hypothesis” proposes that high levels of CORT arise from challenging environmental conditions, resulting in lower reproductive success (a negative relationship). In contrast, the “CORT-adaptation hypothesis” suggests that, during energetically demanding periods, CORT will mediate physiological or behavioural changes that result in increased reproductive investment and success (a positive relationship). During two breeding seasons, we experimentally manipulated circulating CORT levels in female tree swallows (Tachycineta bicolor) prior to egg laying, and measured subsequent reproductive effort, breeding success, and maternal survival. When females were recaptured during egg incubation and again during the nestling stage, the CORT levels were similar among individuals in each treatment group, and maternal treatment had no effect on indices of fitness. By considering variation among females, we found support for the “CORT-adaptation hypothesis”; there was a significant positive relationship between CORT levels during incubation and hatching and fledging success. During the nestling stage CORT levels were unrelated to any measure of investment or success. Within the environmental context of our study, relationships between maternal glucocorticoid levels and indices fitness vary across reproductive stages.SUMMARY STATEMENTMaternal corticosterone levels predict breeding success of female tree swallows.

scholarly journals Maternal glucocorticoid levels during incubation predict breeding success, but not reproductive investment, in a free-ranging bird

Biology Open ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. bio045898
Author(s):  
Devin Fischer ◽  
Robby R. Marrotte ◽  
Eunice H. Chin ◽  
Smolly Coulson ◽  
Gary Burness
Keyword(s):  
Breeding Success ◽  
Positive Relationship ◽  
Negative Relationship ◽  
Reproductive Investment ◽  
Egg Laying ◽  
Maternal Survival ◽  
Adaptation Hypothesis ◽  
Breeding Seasons ◽  
Free Ranging ◽  
The Relationship

ABSTRACTThe hormone corticosterone (CORT) has been hypothesized to be linked with fitness, but the directionality of the relationship is unclear. The ‘CORT-fitness hypothesis’ proposes that high levels of CORT arise from challenging environmental conditions, resulting in lower reproductive success (a negative relationship). In contrast, the CORT-adaptation hypothesis suggests that, during energetically demanding periods, CORT will mediate physiological or behavioral changes that result in increased reproductive investment and success (a positive relationship). During two breeding seasons, we experimentally manipulated circulating CORT levels in female tree swallows (Tachycineta bicolor) prior to egg laying, and measured subsequent reproductive effort, breeding success, and maternal survival. When females were recaptured during egg incubation and again during the nestling stage, the CORT levels were similar among individuals in each treatment group, and maternal treatment had no effect on indices of fitness. By considering variation among females, we found support for the CORT-adaptation hypothesis; there was a significant positive relationship between CORT levels during incubation and hatching and fledging success. During the nestling stage CORT levels were unrelated to any measure of investment or success. Within the environmental context of our study, relationships between maternal glucocorticoid levels and indices of fitness vary across reproductive stages.

scholarly journals The stress of parenthood? Increased glucocorticoids in birds with experimentally enlarged broods

2011 ◽  
Vol 7 (6) ◽  
pp. 944-946 ◽  
Author(s):  
Frances Bonier ◽  
Ignacio T. Moore ◽  
Raleigh J. Robertson
Keyword(s):  
Positive Relationship ◽  
Reproductive Effort ◽  
Reproductive Investment ◽  
Tachycineta Bicolor ◽  
Relative Fitness ◽  
Allocation Of Resources ◽  
Tree Swallows ◽  
Parental Behaviour ◽  
Poor Condition ◽  
Before And After

Variation in baseline glucocorticoid (cort) levels can be attributed, at least in part, to differences in energetic demands confronting individuals. Elevated baseline cort levels are routinely interpreted as indicating individuals in poor condition, with low relative fitness. However, when greater reproductive effort increases energetic demands, individuals with high cort might paradoxically be those with the highest fitness. Here, we experimentally test the hypothesis that increased reproductive demand causes increases in baseline cort (the Cort-Adaptation hypothesis). We measured maternal baseline cort before and after experimentally enlarging and reducing brood sizes in tree swallows ( Tachycineta bicolor ). Females with experimentally enlarged broods had greater increases in baseline cort and fledged more offspring than females with reduced broods. Additionally, females with greater increases in baseline cort had higher offspring-provisioning rates than females with lower changes in cort. These findings demonstrate that increased reproductive demand can cause increased baseline cort. As yet, we do not know if these increases in cort cause increased allocation of resources towards reproduction, but the positive relationship between parental behaviour and cort suggests that increased cort does not always interfere with reproductive investment, and might instead facilitate it.

Effects of the Iron Baron oil spill on little penguins (Eudyptula minor). III. Breeding success of rehabilitated oiled birds

2000 ◽  
Vol 27 (6) ◽  
pp. 583 ◽  
Author(s):  
M. Giese ◽  
S. D. Goldsworthy ◽  
R. Gales ◽  
N. Brothers ◽  
J. Hamill
Keyword(s):  
Breeding Season ◽  
Oil Spill ◽  
Breeding Success ◽  
Egg Laying ◽  
Long Term Effects ◽  
Short Term ◽  
Significant Difference ◽  
Breeding Seasons

The long-term effects of oiling on the breeding success of rehabilitated oiled little penguins (Eudyptula minor) were examined over two consecutive breeding seasons following the Iron Baron oil spill in 1995. The commencement of egg laying was delayed among rehabilitated oiled penguins compared with non-oiled birds during the 1995/96 breeding season. During that season, hatching success (number of eggs hatched from those laid) was no different in nests containing rehabilitated oiled penguins than in those containing non-oiled birds, but overall egg success (number of pre-fledging chicks from the number of eggs laid) was significantly lower among rehabilitated oiled birds. This effect was predominant in nests containing a rehabilitated oiled female, where the probability of successfully fledging any chicks was 22% lower than in nests containing a non-oiled female. During the 1996/97 breeding season, there was no significant difference between either the hatching or egg success of rehabilitated oiled penguins and non-oiled birds. In both seasons, the pre-fledging masses of chicks from rehabilitated oiled penguins were significantly lower than those from non-oiled birds. The chicks of rehabilitated oiled penguins were therefore expected to have lower survival than chicks raised by non-oiled parents. Results indicate that oiling not only reduced the number of chicks raised by rehabilitated oiled penguins in the short term, but also decreased the quality of young produced for at least two seasons following the spill.

scholarly journals Humoral immunocompetence correlates with date of egg-laying and reflects work load in female tree swallows

2001 ◽  
Vol 12 (1) ◽  
pp. 93-97 ◽  
Author(s):  
Dennis Hasselquist ◽  
Matthew F. Wasson ◽  
David W. Winkler
Keyword(s):  
Work Load ◽  
Egg Laying ◽  
Tree Swallows ◽  
Female Tree

scholarly journals Carry-over body mass effect from winter to breeding in a resident seabird, the little penguin

2015 ◽  
Vol 2 (1) ◽  
pp. 140390 ◽  
Author(s):  
Marcus Salton ◽  
Claire Saraux ◽  
Peter Dann ◽  
André Chiaradia
Keyword(s):  
Sex Differences ◽  
Body Mass ◽  
Breeding Success ◽  
Mass Effect ◽  
Egg Laying ◽  
Austral Winter ◽  
Carry Over ◽  
Breeding Seasons ◽  
Little Penguin ◽  
Carry Over Effect

Using body mass and breeding data of individual penguins collected continuously over 7 years (2002–2008), we examined carry-over effects of winter body mass on timing of laying and breeding success in a resident seabird, the little penguin ( Eudyptula minor ). The austral winter month of July consistently had the lowest rate of colony attendance, which confirmed our expectation that penguins work hard to find resources at this time between breeding seasons. Contrary to our expectation, body mass in winter (July) was equal or higher than in the period before (‘moult-recovery’) and after (‘pre-breeding’) in 5 of 7 years for males and in all 7 years for females. We provided evidence of a carry-over effect of body mass from winter to breeding; females and males with higher body mass in winter were more likely to breed early and males with higher body mass in winter were likely to breed successfully. Sex differences might relate to sex-specific breeding tasks, where females may use their winter reserves to invest in egg-laying, whereas males use their winter reserves to sustain the longer fasts ashore during courtship. Our findings suggest that resident seabirds like little penguins can also benefit from a carry-over effect of winter body mass on subsequent breeding.

Reproduction of Pied Flycatchers (Ficedula hypoleuca) in Good and Bad Breeding Seasons in a Northern Marginal Area

The Auk ◽  
1984 ◽  
Vol 101 (3) ◽  
pp. 439-450 ◽  
Author(s):  
Antero Järvinen ◽  
Risto A. Väisänen
Keyword(s):  
Breeding Success ◽  
Egg Size ◽  
Local Population ◽  
Ficedula Hypoleuca ◽  
Nesting Success ◽  
Egg Laying ◽  
Female Size ◽  
Finnish Lapland ◽  
Breeding Seasons ◽  
Better Than

Abstract We studied relationships between female size, date of egg laying, clutch size, egg size, and breeding success in Pied Flycatchers (Ficedula hypoleuca) in a marginal area in northwestern Finnish Lapland (69°N). Average June temperatures in 1975-1981 were used to classify years into "good" (warm) and "bad" (cold) breeding seasons. In general, early and warm springs were followed by "good" breeding seasons: females were heavier, laying was earlier, clutches were larger and contained larger eggs, and hatching and fledging success were better than in late and cold springs. Mainly due to low nesting success in "bad" breeding seasons, the local population could not maintain itself; immigration from the south was needed. We suggest that spring weather may provide information concerning the character of the coming breeding season, which may help birds to maximize their lifetime production of young.

scholarly journals Establishment of introduced reptiles increases with the presence and richness of native congeners

2012 ◽  
Vol 33 (3-4) ◽  
pp. 387-392 ◽  
Author(s):  
Rodrigo B. Ferreira ◽  
Karen H. Beard ◽  
Stephen L. Peterson ◽  
Sharon A. Poessel ◽  
Colin M. Callahan
Keyword(s):  
Early Detection ◽  
Positive Relationship ◽  
Life Form ◽  
Negative Relationship ◽  
Invasion Success ◽  
Niche Space ◽  
Closely Related Species ◽  
Establishment Success ◽  
Mixed Support ◽  
Adaptation Hypothesis

Darwin proposed two contradictory hypotheses to explain the influence of congeners on the outcomes of invasion: the naturalization hypothesis, which predicts a negative relationship between the presence of congeners and invasion success, and the pre-adaptation hypothesis, which predicts a positive relationship between the presence of congeners and invasion success. Studies testing these hypotheses have shown mixed support. We tested these hypotheses using the establishment success of non-native reptiles and congener presence/absence and richness across the globe. Our results demonstrated support for the pre-adaptation hypothesis. We found that globally, both on islands and continents, establishment success was higher in the presence than in the absence of congeners and that establishment success increased with increasing congener richness. At the life form level, establishment success was higher for lizards, marginally higher for snakes, and not different for turtles in the presence of congeners; data were insufficient to test the hypotheses for crocodiles. There was no relationship between establishment success and congener richness for any life form. We suggest that we found support for the pre-adaptation hypothesis because, at the scale of our analysis, native congeners represent environmental conditions appropriate for the species rather than competition for niche space. Our results imply that areas to target for early detection of non-native reptiles are those that host closely related species.

Signaling Subordinate and Female Status: Two Hypotheses for the Adaptive Significance of Subadult Plumage in Female Tree Swallows

The Auk ◽  
1987 ◽  
Vol 104 (4) ◽  
pp. 717-723 ◽  
Author(s):  
Bridget J. Stutchbury ◽  
Raleigh J. Robertson
Keyword(s):  
Adaptive Significance ◽  
Egg Laying ◽  
Tree Swallow ◽  
Tree Swallows ◽  
Young Females ◽  
Female Status ◽  
Female Tree ◽  
Nesting Sites ◽  
Plumage Maturation ◽  
Subadult Female

Abstract Delayed plumage maturation in males is relatively common among North American passerines, but the Tree Swallow (Tachycineta bicolor) is one of few species in which 1-yr-old females have a distinct subadult plumage. Although they are reproductively mature, most subadult females do not breed in their first year because of intense intrasexual competition for nesting sites. Early in the season, subadult female floaters explore for recently vacated nest sites. The subadult plumage of young females could be adaptive by communicating their low threat to residents, thereby decreasing the cost of this exploration. To determine whether resident aggression depends on intruder color, we observed live intrusions and conducted model presentations. When the resident female was out of sight or did not respond to intruders, resident males were significantly less aggressive toward subadult females than toward adult intruders in both the nest-building/egg-laying and incubation stages. Early in the season, resident females were equally aggressive toward subadult female and adult intruders. When presented simultaneously with adult and subadult female models, resident males were always more aggressive toward the adult model, whereas females were aggressive toward either model. We propose two hypotheses for the adaptive significance of subadult plumage in female Tree Swallows: subordinance signaling and sex signaling. Our results suggest that subadult females may reduce resident aggression by signaling their female status to resident males, rather than by signaling their subordinate status to resident females.

Radio-tracking of female Tree Swallows prior to egg-laying

2005 ◽  
Vol 76 (3) ◽  
pp. 259-263 ◽  
Author(s):  
Peter O. Dunn ◽  
Linda A. Whittingham
Keyword(s):  
Egg Laying ◽  
Radio Tracking ◽  
Tree Swallows ◽  
Female Tree

Experimental increase in female mass during the fertile phase leads to enhanced extra-pair paternity in pied flycatchers Ficedula hypoleuca

2019 ◽  
Author(s):  
Mireia Plaza ◽  
Alejandro Cantarero ◽  
Juan Moreno
Keyword(s):  
Negative Relationship ◽  
Ficedula Hypoleuca ◽  
Egg Laying ◽  
Female Dominance ◽  
Laying Date ◽  
Control Group ◽  
Wing Loading ◽  
Potential Fecundity ◽  
Fertile Phase ◽  
Extra Pair Paternity

Female mass in most altricial birds reaches its maximum during breeding at egg-laying, which coincides temporally with the fertile phase when extra-pair paternity (EPP) is determined. Higher mass at laying may have two different effects on EPP intensity. On the one hand, it would lead to increased wing loading (body mass/wing area), which may impair flight efficiency and thereby reduce female’s capacity to resist unwanted extra-pair male approaches (sexual conflict hypothesis). On the other hand, it would enhance female condition, favouring her capacity to evade mate-guarding and to search for extra-pair mates (female choice hypothesis). In both cases, higher female mass at laying may lead to enhanced EPP. To test this prediction, we reduced nest building effort by adding a completely constructed nest in an experimental group of female pied flycatchers (Ficedula hypoleuca). Our treatment caused an increase in mass and thereby wing loading and this was translated into a significantly higher EPP in the manipulated group compared with the control group as expected. There was also a significant negative relationship between EPP and laying date and the extent of the white wing patch, an index of female dominance. More body reserves at laying mean not only a higher potential fecundity but a higher level of EPP as well. This interaction had not previously received due attention but should be considered in future studies of avian breeding strategies.

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