TIME-SPECIFIC VARIATION IN PASSERINE NEST SURVIVAL: NEW INSIGHTS INTO OLD QUESTIONS

Abstract Understanding nest survival is critical to bird conservation and to studies of avian life history. Nest survival likely varies with nest age and date, but until recently researchers had only limited tools to efficiently address those sources of variability. Beginning with Mayfield (1961), many researchers have averaged survival rates within time-specific categories (e.g. egg and nestling stages; early and late nesting dates). However, Mayfield’s estimator assumes constant survival within categories, and violations of that assumption can lead to biased estimates. We used the logistic-exposure method to examine nest survival as a function of nest age and date in Clay-colored Sparrows (Spizella pallida) and Vesper Sparrows (Pooecetes gramineus) breeding in north-central North Dakota. Daily survival rates increased during egg laying, decreased during incubation to a low shortly after hatch, and then increased during brood rearing in both species. Variation in survival with nest age suggests that traditional categorical averaging using Mayfield’s or similar methods would have been inappropriate for this study; similar variation may bias results of other studies. Nest survival also varied with date. For both species, survival was high during the peak of nest initiations in late May and early June and declined throughout the remainder of the nesting season. On the basis of our results, we encourage researchers to consider models of nest survival that involve continuous time-specific explanatory variables (e.g. nest age or date). We also encourage researchers to document nest age as precisely as possible (e.g. by candling eggs) to facilitate age-specific analyses. Models of nest survival that incorporate time-specific information may provide insights that are unavailable from averaged data. Determining time-specific patterns in nest survival may improve our understanding of predator-prey interactions, evolution of avian life histories, and aspects of population dynamics that are critical to bird conservation.

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Effects of intrinsic and time-specific factors on daily nest survival of birds in a semiarid area of South America (Caatinga)

Revista Brasileira de Ornitologia ◽

10.1007/bf03544351 ◽

2016 ◽

Vol 24 (3) ◽

pp. 228-234 ◽

Cited By ~ 4

Author(s):

Leonardo Fernandes França ◽

Camila Melo da Silva ◽

Luciana Vieira de Paiva

Keyword(s):

South America ◽

Nest Survival ◽

Semiarid Area ◽

Daily Nest Survival ◽

Specific Factors ◽

Time Specific

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Time-specific patterns of nest survival for ducks and passerines breeding in North Dakota

The Auk ◽

10.1525/auk.2012.11064 ◽

2012 ◽

Vol 129 (2) ◽

pp. 319-328 ◽

Cited By ~ 23

Author(s):

Todd A. Grant ◽

Terry L. Shaffer

Keyword(s):

North Dakota ◽

Nest Survival ◽

Time Specific

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Drivers of nest survival in the Tawny-bellied Seedeater Sporophila hypoxantha (Aves: Thraupidae): time-specific factors are more related to success than ecological variables

Anais da Academia Brasileira de Ciências ◽

10.1590/0001-3765202120191458 ◽

2021 ◽

Vol 93 (suppl 3) ◽

Author(s):

ISMAEL FRANZ ◽

CARLA S. FONTANA

Keyword(s):

Nest Survival ◽

Ecological Variables ◽

Specific Factors ◽

Time Specific

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A Unified Approach to Analyzing Nest Success

The Auk ◽

10.1093/auk/121.2.526 ◽

2004 ◽

Vol 121 (2) ◽

pp. 526-540 ◽

Cited By ~ 1

Author(s):

Terry L. Shaffer

Keyword(s):

Logistic Regression ◽

Linear Models ◽

Nest Success ◽

Nest Survival ◽

Exposure Model ◽

Survival Models ◽

Suitable Alternative ◽

Explanatory Variables ◽

Exposure Method ◽

Time Specific

Abstract Logistic regression has become increasingly popular for modeling nest success in terms of nest-specific explanatory variables. However, logistic regression models for nest fate are inappropriate when applied to data from nests found at various ages, for the same reason that the apparent estimator of nest success is biased (i.e. older clutches are more likely to be successful than younger clutches). A generalized linear model is presented and illustrated that gives ornithologists access to a flexible, suitable alternative to logistic regression that is appropriate when exposure periods vary, as they usually do. Unlike the Mayfield method (1961, 1975) and the logistic regression method of Aebischer (1999), the logistic-exposure model requires no assumptions about when nest losses occur. Nest survival models involving continuous and categorical explanatory variables, multiway classifications, and time-specific (e.g. nest age) and random effects are easily implemented with the logistic-exposure model. Application of the model to a sample of Yellow-breasted Chat (Icteria virens) nests shows that logistic-exposure estimates for individual levels of categorical explanatory variables agree closely with estimates obtained with Johnson (1979) constant-survival estimator. Use of the logistic-exposure method to model time-specific effects of nest age and date on survival of Blue-winged Teal (Anas discors) and Mallard (A. platyrhynchos) nests gives results comparable to those reported by Klett and Johnson (1982). However, the logistic-exposure approach is less subjective and much easier to implement than Klett and Johnson's method. In addition, logistic-exposure survival rate estimates are constrained to the (0,1) interval, whereas Klett and Johnson estimates are not. When applied to a sample of Mountain Plover (Charadrius montanus) nests, the logistic-exposure method gives results either identical to, or similar to, those obtained with the nest survival model in program MARK (White and Burnham 1999). I illustrate how the combination of generalized linear models and information-theoretic techniques for model selection, along with commonly available statistical software, provides ornithologists with a powerful, easily used approach to analyzing nest success.

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Sex ratio estimation and survival analysis for Orthetrum coerulescens (Odonata, Libellulidae)

Canadian Journal of Zoology ◽

10.1139/z04-004 ◽

2004 ◽

Vol 82 (3) ◽

pp. 399-406 ◽

Cited By ~ 10

Author(s):

M Kéry ◽

L Juillerat

Keyword(s):

Sex Ratio ◽

Sex Ratios ◽

Survival Rates ◽

Activity Period ◽

Time Interval ◽

Ratio Estimation ◽

Capture Recapture ◽

Specific Variation ◽

Population Survival ◽

Time Specific

There is controversy over whether uneven sex ratios observed in mature dragonfly populations are a mere artifact resulting from the higher observability of males. Previous studies have at best made indirect inference about sex ratios by analysis of survival or recapture rates. Here, we obtain direct estimates of sex ratio from capturerecapture data based on the CormackJollySeber model. We studied Orthetrum coerulescens (Fabricius, 1798) at three sites in the Swiss Jura Mountains over an entire activity period. Recapture rates per 5-day interval were 3.5 times greater for males (0.67, SE 0.02) than for females (0.19, SE 0.02). At two sites, recapture rate increased over the season for males and was constant for females, and at one site it decreased with precipitation for both sexes. In addition, recapture rate was higher with higher temperature for males only. We found no evidence for higher male survival rates in any population. Survival per 5-day interval for both sexes was estimated to be 0.77 (95% CI 0.750.79) without significant site-or time-specific variation. There were clear effects of temperature (positive) and precipitation (negative) on survival rate at two sites. Direct estimates of sex ratios were not significantly different from 1 for any time interval. Hence, the observed male-biased sex ratio in adult O. coerulescens was an artifact resulting from the better observability of males. The method presented in this paper is applicable to sex ratio estimation in any kind of animal.

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Mixed-Grass Prairie Passerines Exhibit Weak and Variable Responses to Patch Size

The Auk ◽

10.1093/auk/123.3.807 ◽

2006 ◽

Vol 123 (3) ◽

pp. 807-821 ◽

Cited By ~ 1

Author(s):

Stephen K. Davis ◽

R. Mark Brigham ◽

Terry L. Shaffer ◽

Paul C. James

Keyword(s):

Tallgrass Prairie ◽

Patch Size ◽

Nest Survival ◽

Bird Populations ◽

Mixed Grass Prairie ◽

Bird Density ◽

Anthus Spragueii ◽

Mixed Grass ◽

Sprague's Pipit ◽

Time Specific

Abstract Much of our current understanding of the demographic effects of habitat fragmentation on bird populations is derived from studies of passerines in forests and tallgrass prairie surrounded by woody vegetation. We quantified grassland bird density, nest survival, and productivity in 41 native mixed-grass prairie pastures during 1997-2000 in southern Saskatchewan, Canada. Pastures ranged in size from 18 ha to 11,600 ha and were typically surrounded by agriculture (i.e., ranching and annual cropping). Grassland passerines did not respond strongly or uniformly to patch size. Sprague's Pipit (Anthus spragueii) was the only species whose density increased with pasture size. Patch size had minimal influence on nest survival of Sprague's Pipit or Clay-colored Sparrow (Spizella pallida); whereas nest survival increased with patch size for Savannah Sparrow (Passerculus sandwichensis) and declined for Baird's Sparrow (Ammodramus bairdii), Chestnut-collared Longspur (Calcarius ornatus), and Western Meadowlark (Sturnella neglecta). Time-specific factors (i.e., nest age, date, and year) were more important predictors of nest survival than patch size. Exploratory analyses indicated that effects of edge distance, pasture shape, or landscape on nest survival were just as likely as patch-size effects. However, effects of edge on Chestnut-collared Longspurs may be governed by landscape-level factors, because nest survival decreased with distance to edge in landscapes with increased amounts of cropland. Our results indicate that mixed-grass prairie parcels ≥18 ha play a role in the conservation of several grassland passerine species currently in decline, but the conservation of Sprague's Pipit likely depends on maintaining larger tracts of native prairie. Les Passereaux des Prairies Herbacées Montrent des Réponses Faibles et Variables en Réponse à la Taille des Parcelles d'Habitats

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