Clutch size variation in passerine birds: The nest predation hypothesis

Abstract Background Growth trajectories should be adapted to selective factors of each species’ environment. However, major shaping forces of growth and development are unclear, especially when studying several traits at once. Birds provide an ideal opportunity to analyze growth patterns across species due to there being enough available data. We tested the relative importance of nest predation risk, the number of care-givers, nest height, foraging substrate, clutch size, and latitude on growth patterns of passerine birds (Passeriformes) using phylogenetic comparative methods. Specifically, we studied the evolution of fledging time, average and peak growth rates, and relative development at fledging of body mass and tarsus, wing, and tail length. Results Using a comprehensive literature search and data quality control, we obtained data on growth in 231 species based on 295 populations. Species with long development in the nest grew slowly and had well-developed traits at fledging. Species breeding under high nest predation risk, building their nests close to the ground, and those living in northern temperate regions fledged early and grew fast, sometimes fledging with less developed body mass and traits critical for locomotion (tarsus, wing, and tail). On the other hand, the number of caring adults, clutch size, and species’ foraging substrate had very limited predictive value for growth patterns across passerine species. Conclusions Shortening of the nestling period was a primary means of accelerating development (in relation to nest predation, nest height, and latitude), sometimes supplemented by higher peak growth rates of body mass, tarsus, and wing (especially in relation to latitude). Overall growth patterns of passerines were adaptively tuned to nest predation risk and nest height, with northern temperate species having especially short nestling periods and fast growth rates of body mass, tarsus, and wing.

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Elevated nest predation risk promotes offspring size variation in birds with prolonged parental care.

10.32942/osf.io/h2mpw ◽

2019 ◽

Author(s):

Gretchen F. Wagner ◽

Emeline Mourocq ◽

Michael Griesser

Keyword(s):

Predation Risk ◽

Reproductive Cycle ◽

Perceived Risk ◽

Nest Predation ◽

Bird Species ◽

Size Variation ◽

Egg Laying ◽

Offspring Size ◽

Natural Predation ◽

Risk Spreading

Predation of offspring is the main cause of reproductive failure in many species, and the mere fear of offspring predation shapes reproductive strategies. Yet, natural predation risk is ubiquitously variable and can be unpredictable. Consequently, the perceived prospect of predation early in a reproductive cycle may not reflect the actual risk to ensuing offspring. An increased variance in investment across offspring has been linked to breeding in unpredictable environments in several taxa, but has so far been overlooked as a maternal response to temporal variation in predation risk. Here, we experimentally increased the perceived risk of nest predation prior to egg-laying in seven bird species. Species with prolonged parent-offspring associations increased their intra-brood variation in egg, and subsequently offspring, size. High risk to offspring early in a reproductive cycle can favour a risk-spreading strategy particularly in species with the greatest opportunity to even out offspring quality after fledging.

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Glucocorticoids, state-dependent reproductive investment and success in the face of danger in a long-lived bird

Journal of Ornithology ◽

10.1007/s10336-020-01847-9 ◽

2020 ◽

Author(s):

Kristina Noreikienė ◽

Kim Jaatinen ◽

Benjamin B. Steele ◽

Markus Öst

Keyword(s):

Predation Risk ◽

Telomere Length ◽

Clutch Size ◽

Body Condition ◽

Nest Predation ◽

Hatching Success ◽

Reproductive Investment ◽

Trade Off ◽

Relative Telomere Length ◽

Future Reproduction

AbstractGlucocorticoid hormones may mediate trade-offs between current and future reproduction. However, understanding their role is complicated by predation risk, which simultaneously affects the value of the current reproductive investment and elevates glucocorticoid levels. Here, we shed light on these issues in long-lived female Eiders (Somateria mollissima) by investigating how current reproductive investment (clutch size) and hatching success relate to faecal glucocorticoid metabolite [fGCM] level and residual reproductive value (minimum years of breeding experience, body condition, relative telomere length) under spatially variable predation risk. Our results showed a positive relationship between colony-specific predation risk and mean colony-specific fGCM levels. Clutch size and female fGCM were negatively correlated only under high nest predation and in females in good body condition, previously shown to have a longer life expectancy. We also found that younger females with longer telomeres had smaller clutches. The drop in hatching success with increasing fGCM levels was least pronounced under high nest predation risk, suggesting that elevated fGCM levels may allow females to ensure some reproductive success under such conditions. Hatching success was positively associated with female body condition, with relative telomere length, particularly in younger females, and with female minimum age, particularly under low predation risk, showing the utility of these metrics as indicators of individual quality. In line with a trade-off between current and future reproduction, our results show that high potential for future breeding prospects and increased predation risk shift the balance toward investment in future reproduction, with glucocorticoids playing a role in the resolution of this trade-off.

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One or two eggs: what underlies clutch size variation within a gecko species?

Zoology ◽

10.1016/j.zool.2021.125911 ◽

2021 ◽

pp. 125911

Author(s):

Osamu Sakai

Keyword(s):

Clutch Size ◽

Size Variation

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Geographical differences in seasonal clutch size variation in multi-brooded bird species

Ibis ◽

10.1046/j.1474-919x.2002.00103.x ◽

2002 ◽

Vol 144 (4) ◽

pp. 646-651 ◽

Cited By ~ 26

Author(s):

André A. Dhondt ◽

Tracey L. Kast ◽

Paul E. Allen

Keyword(s):

Clutch Size ◽

Bird Species ◽

Size Variation ◽

Geographical Differences

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The influence of subcolony-scale nesting habitat on the reproductive success of Adélie penguins

Scientific Reports ◽

10.1038/s41598-021-94861-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Annie E. Schmidt ◽

Grant Ballard ◽

Amélie Lescroël ◽

Katie M. Dugger ◽

Dennis Jongsomjit ◽

...

Keyword(s):

Reproductive Success ◽

Colony Size ◽

Nest Predation ◽

Size Variation ◽

Area Ratio ◽

Slope Aspect ◽

Nesting Habitat ◽

Terrain Attributes ◽

Small Colony ◽

Adélie Penguins

AbstractGroup-size variation is common in colonially breeding species, including seabirds, whose breeding colonies can vary in size by several orders of magnitude. Seabirds are some of the most threatened marine taxa and understanding the drivers of colony size variation is more important than ever. Reproductive success is an important demographic parameter that can impact colony size, and it varies in association with a number of factors, including nesting habitat quality. Within colonies, seabirds often aggregate into distinct groups or subcolonies that may vary in quality. We used data from two colonies of Adélie penguins 73 km apart on Ross Island, Antarctica, one large and one small to investigate (1) How subcolony habitat characteristics influence reproductive success and (2) How these relationships differ at a small (Cape Royds) and large (Cape Crozier) colony with different terrain characteristics. Subcolonies were characterized using terrain attributes (elevation, slope aspect, slope steepness, wind shelter, flow accumulation), as well group characteristics (area/size, perimeter-to-area ratio, and proximity to nest predators). Reproductive success was higher and less variable at the larger colony while subcolony characteristics explained more of the variance in reproductive success at the small colony. The most important variable influencing subcolony quality at both colonies was perimeter-to-area ratio, likely reflecting the importance of nest predation by south polar skuas along subcolony edges. The small colony contained a higher proportion of edge nests thus higher potential impact from skua nest predation. Stochastic environmental events may facilitate smaller colonies becoming “trapped” by nest predation: a rapid decline in the number of breeding individuals may increase the proportion of edge nests, leading to higher relative nest predation and hindering population recovery. Several terrain covariates were retained in the final models but which variables, the shapes of the relationships, and importance varied between colonies.

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Clutch Size Variation and Patterns of Attrition in Fecundity of Willow Ptarmigan

Ecology ◽

10.2307/1938112 ◽

1989 ◽

Vol 70 (6) ◽

pp. 1788-1799 ◽

Cited By ~ 35

Author(s):

K. Martin ◽

S. J. Hannon ◽

R. F. Rockwell

Keyword(s):

Clutch Size ◽

Size Variation ◽

Willow Ptarmigan

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Extreme rainfall-related clutch size variation in the Critically Endangered Raso Lark Alauda razae of the arid Cape Verde islands

Bird Conservation International ◽

10.1017/s0959270918000163 ◽

2018 ◽

Vol 29 (2) ◽

pp. 321-326 ◽

Cited By ~ 6

Author(s):

M. de L. BROOKE

Keyword(s):

Population Size ◽

Clutch Size ◽

Size Variation ◽

Extreme Rainfall ◽

Cape Verde ◽

Critically Endangered ◽

Strongly Correlated ◽

Cape Verde Islands ◽

Rainy Period ◽

Island Endemic

SummaryThe Raso Lark Alauda razae is a single island endemic confined to the island of Raso in the Cape Verde islands. It has been studied via short (11–20 day), similarly-timed visits every year from 2001 to 2017. These November/December visits have occurred towards the end of the main rainy period (August–October) in the Cape Verdes. Average clutch size ranged from zero (no nests found) to 3.57 in different years and was strongly correlated with rainfall in the three months preceding the year’s visit, but not with population size, which varied 25-fold during the study period. Since the nomadic pursuit of rain is not an option for the Raso Lark, the species adjusts clutch size according to conditions prevailing on Raso.

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