Late Nests Research Articles

Hatching and Emergence Patterns in the Yellow-Spotted River Turtle,Podocnemis unifilis(Testudines: Podocnemididae), in theVárzeaFloodplains of the Lower Amazon River in Santarém, Brazil

In reptiles, the hatching and emergence of a single clutch may be synchronized or may take place over a number of days, weeks, or even months, depending primarily on the microenvironment of the nest. The present study focused on the patterns of hatching and emergence of Podocnemis unifilis hatchlings in an area of várzea floodplain on the lower Amazon River in Santarém, in the Brazilian state of Pará, in 2007 and 2009. Two groups of nests were monitored for hatching and emergence, with the nests in one group being undisturbed during the entire study period. The difference between the oviposition–hatching and oviposition–emergence intervals was determined based on the monitoring of these processes in the monitored clutches. Hatchlings took 1.5 d to leave the eggshell and the eggs at the top of the nest hatched first. The size of the clutch influenced the length of the interval between the first and last hatching. Most hatchlings emerged from a nest during a single night. Hatchlings in late nests and those closer to vegetation took significantly longer to emerge. The hatching–emergence interval was greater in 2007 (11.0 d) than in 2009 (7.3 d). This study contributes to the understanding of hatching and emergence patterns in P. unifilis and the physical and environmental factors that influence them, including the variation between reproductive seasons.

Late Nest Leaving in Portugal

In Southern European countries, the number of emerging adults living with their parents is particularly high; however, the developmental and relational implications of this situation has not been yet systemically studied. Therefore, the present study aimed to (a) examine how emerging adult’s individuation process (i.e. conflictual, functional and financial independence) and the quality of parent–child relationship relationships (i.e. satisfaction and criticism) was related to emerging adult’s living arrangements and (b) investigate how the different individuation domains were associated with parent–child relationships and additionally test the moderation effect of living arrangements in this process. Four hundred and fifty-seven Portuguese emerging adults of age between 20 and 29 were assessed through self-report questionnaires. Results showed that living arrangements were associated with interpersonal forms of independence but were unrelated to the quality of parent–child relations. Moreover, distinct domains of individuation differently predicted parent–child relationships.

Parental Provisioning by Carolina Wrens

We studied nestling provisioning and male song behavior associated with provisioning by Carolina Wrens (Thryothorus ludovicianus) throughout the nestling period. Overall, males and females (n = 14 pairs) provisioned at similar rates throughout four nestling stages although males tended to provision more at the earliest nest stage (1–3 days). Males and females increased their rate of provisioning progressively over the nestling period. Parents brought one food item at a time to the nest and load sizes were similar between males and females, and between early and late nest stages. Males sang 34% of the time on arrival at nests to provision and 49% on leaving nests after provisioning. There was no relationship between male song and age of the nestlings. Males sang more after provisioning nestlings when females were not present (55%) than when females were present (33%) at the nest. The function of male song during provisioning may be to communicate the male's location to the female and to indicate he has recently provisioned the nestlings but this requires further study.

Handicapped females receive more feedings during incubation from their mates: support for the female nutrition hypothesis

The female nutrition hypothesis posits that provisioning intensity of incubating females by their mates may depend on female needs and ensure proper incubation and a corresponding high hatching and breeding success of breeding pairs. Here, we have handicapped female pied flycatchers Ficedula hypoleuca at the beginning of incubation by clipping two primaries on each wing and filmed nests during incubation and later nestling provisioning to estimate male involvement in incubation feeding at the nest and in offspring care. Incubation feeding was more frequent at late nests. Correcting for this seasonal effect, incubation feeding was significantly affected by treatment and twice as high at experimental as at control nests. There was no effect of the experiment on female incubation attendance. The handicap did not result in any effect on hatching and breeding success, nestling growth and male or female provisioning and mass at the end of the nestling period. Males adjust their incubation feeding activity at the nest to female energetic requirements during incubation.

Sources of variation in the nesting success of understory tropical birds

Survival of offspring is a key fitness component and, for birds, the threat of predation on nests is especially influential. Data on rates of nest success from tropical regions are comparatively few, conservation‐relevant, and essential for assessing the validity of models comparing the life histories and behavior or birds across latitudinal gradients. We monitored over 2 000 nests in the lowland forests of central Panama and, using the logistic exposure to model the fate of nests, explored the importance of variation in rate of nest success according to type of nest, height of nests, among years, in early versus late nests, and at different stages of the nest cycle. Analyses of over 1 400 nests for 18 species revealed considerable variation among species in the daily survival rate of nests (range among 18 species=0.91 to 0.98), but nest type and stage of the nesting cycle were generally influential on the probability of nest success. Cavity or enclosed nesters experienced greater nest success than open cup nesters and rates of nest loss were generally greatest in the nestling stage. We found limited evidence that height of nests affected probability of success, but no indication that timing of nesting effort was influential. Despite the occurrence of a severe ENSO event during our sampling, annual variation in nest success was not consistent among species. Interspecific variation in the rates and patterns of nest predation in our study, coupled with reports of high rates of nest loss at temperate latitudes, lead us to question long standing assumptions about latitudinal trends in rates of nest loss. We urge further work to understand the implications of nest predation on the evolutionary ecology of tropical birds.

Do parasitic common goldeneyeBucephala clangulafemales choose nests on the basis of host traits or nest site traits?

Conspecific brood parasitism (CBP) is an important alternative breeding strategy for gaining reproductive output in birds. While interactions between hosts and parasites and consequences of CBP to breeding success of both parties have been studied a lot, the roles of host characteristics and nest site characteristics in CBP have received less attention. We studied the relative importance of host‐related traits, such as female condition and breeding experience, and nest‐site‐related factors, such as overall nest site preference and occupation rate, in explaining the occurrence of CBP in a common goldeneyeBucephala clangulapopulation. We used spatially and temporally extensive data sets, analysed the data with generalized linear mixed models that allowed us to account for the non‐independency of individual nesting attempts across females and nesting sites, and used an information theoretic approach in model selection and inference. About half of the nests were parasitized annually during the seven year study period. The occurrence of CBP decreased with advancement of the breeding season but late nests were also frequently parasitized. We found that the occurrence of CBP was better explained by nest‐site characteristics than host traits, implying that parasitic females target a given nest based on factors related to the nest site itself rather than on the host. Our results suggest that more attention should be paid to factors associated with nest site attractiveness and quality when studying laying decisions of parasites and the occurrence of CBP in general.

Temporal and sex-specific variation in growth rates of Marabou Stork Leptoptilos crumeniferus chicks

The nesting success of Marabou Storks Leptoptilos crumeniferus breeding in north-eastern Swaziland is closely associated with rainfall, with nests started late in the season exposed to higher rainfall and showing lower success. This may be related to lower food intake and slower growth of the chicks. This study set out to determine whether hatching date and sequence of laying affected the growth rate of chicks. Chicks were also sexed, as Marabou Storks show sexual size dimorphism—males are on average 20% larger—and this trait is often associated with differing patterns of growth between sexes. Nestlings were measured weekly from hatching until they either died or fledged. Nestling development is described in detail and photographs of different-aged chicks are presented. The nestling period was significantly shorter for female chicks, at 94 d, than for male chicks at 104 d. Male and female chicks differed in growth rate and asymptote for both mass and wing length. Unusually, females showed higher instantaneous growth rates for much of the nestling period. Chicks surpassed adult mass before fledging. Date of hatching had an effect on growth rates, with chicks at late nests having slower growth, consistent with a decline in food availability. Marabou Storks appear to be slower growing than expected for the Ciconiidae, the taxonomic family to which they belong.

Environmental Correlates of Reproductive Success for Introduced Resident Whooping Cranes in Florida

Abstract. Reproduction within a recently re-introduced resident flock of Whooping Cranes ( Grus americana) in Florida during 1992–2007 was poor compared to an established wild flock. Pairing and nesting increased with average age of the flock, but fertility, hatching and fledging were variable among years, suggestive of an environmental influence. For climatic variables measured during the incubation period, only maximum soil temperature was associated with the failure of late nests in dry years. However, pre-nesting winter precipitation and water elevation were positively correlated with an index of nesting effort. Winter precipitation was associated with fertility and hatchability, whereas winter marsh water levels were associated with earlier nesting dates and increased egg volume. Both winter precipitation (>8 cm mean monthly) and water elevation (>20.3 m above mean sea level or 68% of full marsh surface area or perimeter) greater than a threshold level appeared to be good predictors for successful re...

Putting density dependence in perspective: nest density, nesting phenology, and biome, all matter to survival of simulated mallard Anas platyrhynchos nests

Breeding success in ground‐nesting birds is primarily determined by nest survival, which may be density‐dependent, but the generality of this pattern remains untested. In a replicated crossover experiment conducted on 30 wetlands, survival of simulated mallard nests was related to “biome” (n=14 mediterranean and 16 boreal wetlands), breeding “phenology” (early vs late nests), and “density” (2 vs 8 nests per 225 m shoreline). Local abundances of “waterfowl”, “other waterbirds”, and “avian predators” were used as covariates. We used an information‐theoretic approach and Program MARK to select among competing models. Nest survival was lower in late nests compared with early ones, and it was lower in the mediterranean than in the boreal study region. High‐density treatment nests suffered higher depredation rates than low‐density nests during days 1–4 of each experimental period. Nest survival was negatively associated with local abundance of “waterfowl” in the boreal but not in the mediterranean biome. Effect estimates from the highest‐ranked model showed that nest “density” (d 1–4) had the strongest impact on model fit; i.e. three times that of “biome” and 1.5 times that of “phenology”. The latter′s effect, in turn, was twice that of “biome”. We argue that our study supports the idea that density‐dependent nest predation may be temporally and spatially widespread in waterfowl. We also see an urgent need for research of how waterfowl nesting phenology is matched to that of prey and vegetation.

A survey of Fairy Tern (Sterna nereis) breeding colonies in the Southern Lagoon, New Caledonia

The breeding success of Fairy Terns in New Caledonia is poorly known despite the species being considered nationally endangered. Between June and October 2004, we surveyed 22 islets and coral banks in the Southern Lagoon of New Caledonia at least once for the presence of breeding Fairy Terns (Sterna nereis). We present the first reports of the breeding success of Fairy Terns in the Southern Lagoon, and compare it with populations in Australia and New Zealand. We observed a protracted nesting period (3 months) and a low overall rate of nesting success (probability of a nest producing at least one fledging, P = 0.19) for colonies on Îlot Kae and Îlot Atire, with a higher fledging rate (P = 0.57) than hatching success (P = 0.34). In addition, no fledglings were produced from late nests. These levels of breeding success were similar to those found for the endangered subspecies of Fairy Tern in New Zealand. The population of Fairy Terns in the Lagoon appears to be increasing after an earlier disappearance of the population from the area. We recommend more regular surveys on the New Caledonian subspecies of Fairy Tern.

Proximate Mechanisms of Parasite Egg Rejection by Northern Mockingbirds

Abstract Northern Mockingbirds (Mimus polyglottos) are known to reject parasitic eggs at an intermediate rate. However, proximate mechanisms of rejection remain unexplored. Our objectives were to examine the rejection behavior of Northern Mockingbirds in northeast Louisiana, explore if nesting date or egg color of parasitic eggs influence the rate that Northern Mockingbirds reject Brown-headed Cowbird (Molothrus ater) eggs, and compare results to those of previous studies. Northern Mockingbirds rejected 68% of artificial eggs. Early nesting individuals rejected 50% of the model eggs and late nesters rejected 82%. Early nesting Northern Mockingbirds rejected 72% of light eggs compared to 27% of dark eggs. Color of the parasitic egg and date of parasitism may influence rejection rates of Northern Mockingbirds.

Reproductive Biology of the Chestnut-backed Chickadee (Poecile rufescens) in Northwestern Oregon

Abstract Chestnut-backed Chickadees were studied over a 4-y period near Portland, Oregon, and for 1 of those years near Eugene, Oregon. Data on nesting activities and nestling growth rates were obtained by monitoring nest boxes. The chickadees began nest-building activity in March, with the 1st eggs being laid in early April and nests continuing to be initiated through early July. The timing of nest initiation was bimodal with the 1st peak in late April and a 2nd, smaller peak in June, referred to as “late nests”. Late nests accounted for 14 of the 94 nests observed. Clutch size for early nests varied from 5 to 10 eggs, with 7- and 8-egg clutches occurring at nearly equal frequency and representing 67.9%. Fledge success was greatest for 9-egg clutches and lowest for the smallest (6 or fewer) and largest (10) clutch sizes. Incubation averaged 13.8 d. The nestling growth phase averaged 18.8 d. Nestling body mass at age 14 d (the growth asymptote) was not correlated with clutch size or 14-d brood size. Late ...

BREEDING ECOLOGY OF AMERICAN AND CARIBBEAN COOTS AT SOUTHGATE POND, ST. CROIX: USE OF WOODY VEGETATION

American (Fulica americana) and Caribbean (F. caribaea) coots nested colonially at brackish Southgate Pond, St. Croix, United States Virgin Islands (USVI), following a 50-year rainfall event in mid-November 2003. Breeding occurred during three time periods: seven pairs bred from 6 December to 2 January (early), seven from 17 January to 15 February (middle), and eight from 26 April to 19 May (late) (range of clutch initiation dates = 165 days). Hatching success was high (65.3%), but overall reproductive success was low (27%) owing to poor brood survival. Coots built all but 2 of 22 nests at the water line in sturdy crotches of small, live white mangroves (Laguncularia racemosa); two late nests were built on remnant stubs of dead white mangroves after water levels had sharply declined. Early pairs nested in manglars (islets of one or more mangroves without solid land) farther away from shore and in deeper water than middle or late pairs (65.6 versus 42.1 and 29.0 cm, respectively). Southgate Pond remains the preferred breeding site for coots on St. Croix and the USVI. Coots have also recently nested on St. Croix at seven semi-permanent or permanent, man-made, freshwater ponds where they have probably been overlooked, as coots respond rapidly to changes in water levels at semi-permanent or permanent wetlands. Predominance of non-assortative pairing at Southgate Pond suggests that American and Caribbean coots are morphs of one species.

Hatching success in Avocet Recurvirostra avosetta and Black-winged Stilt Himantopus himantopus

Capsule Daily survival rate of nests was influenced by laying date and nesting period (laying versus incubation) in both species and by colony size in Black-winged Stilts. Aims To investigate the effect of clutch size, colony size, reproductive phenology and nesting period on hatching success of Avocets and Black-winged Stilts. Methods The study was undertaken at two localities in southwestern Spain (Doñana and Odiel Natural Parks) during 1990 and 1991 breeding seasons. The Mayfield method was used to estimate hatching success. Results Both species bred colonially and some colonies included nests of both species. Neither year, locality, species or clutch size had a significant effect on hatching success. Daily survival rate was lower for late nests than for early and intermediate, and lower during egg-laying than during incubation in both species. Hatching success of Black-winged Stilt nests was lower in large colonies (>50 nests) than in medium-sized ones (11–50 nests). Conclusion Late clutches within a colony (clutches with the least hatching success) might be replacements or belong to late breeders, but adults were not individually marked, precluding clarification. The results suggest a high probability of clutch predation and/or desertion in early stages of the nesting period, especially shortly after laying the first egg. The fact that hatching success in large colonies was lower than in medium-sized ones, but only for Black-winged Stilts (not for Avocets), might help to explain the difference in coloniality of the two species.

Do Changing Moisture Levels during Incubation Influence Phenotypic Traits of Hatchling Snakes (Tropidonophis mairii, Colubridae)?

Phenotypic traits (e.g., size, strength, speed) of hatchlings in many reptile species are influenced by hydric conditions in the nest. Previous experiments have focused on comparisons between eggs maintained under constant (but different) conditions, but eggs in natural nests frequently experience strong temporal shifts in soil water content during incubation. Keelback snakes (Tropidonophis mairii) in the Australian wet-dry tropics nest over most of the year, so early nests experience decreasing water availability during development, late nests experience increases, and others (midyear) remain stable in this respect. We mimicked these three conditions and incubated 54 eggs (nine from each of six clutches) in a split-clutch design to maintain the same average water content but with differing trajectories through incubation. The experimental treatments significantly affected the total amount of water taken up by the eggs (and thus final egg mass), but incubation periods were unaffected. Hatchling size but not strength showed minor but statistically significant effects of incubation regimes. The ability of keelback eggs to take up excess water whenever it becomes available (either early or late in development) and to retain it even when conditions change buffers embryogenesis effectively (but not completely) against fluctuations in soil water conditions.

Effect of intraspecific interactions on seasonal decline in productivity of Common Terns Sterna hirundo

Capsule Kleptoparasitic activities of older chicks from earlier nests did not contribute to late reproductive declines. Aims To determine whether intraspecific interactions, such as kleptoparasitism and aggression, were experienced more frequently by birds breeding late in the season as a result of exposure to breeders at a more advanced stage. If so, to investigate whether this was the cause of the observed seasonal decline in reproductive parameters observed at Bird Island, where nesting density is high and interactions are more probable. Methods Plots were fenced within the colony, exploiting natural variability in distribution of early and peak breeders to create two treatments: plots with only late-laying terns and those with a mixture of early-, peak- and late-layers. Hatching success, productivity and the growth and survival of chicks were measured for all late-laying pairs. Intraspecific interactions, adult attendance and provisioning of chicks were recorded during 9600 minutes of nest observations made within two periods: a few days after hatching and one week later. Results The frequency of intraspecific interactions was maintained by the kleptoparasitic activities of older chicks within the mixed-laying-date treatment and was significantly lower in plots containing only late breeders with chicks of similar ages (mean 11.0 days). The overall rate was rarely greater than two interactions per nest per hour and there was no corresponding reduction in the growth or survival of chicks from late nests or any change in the provisioning activities of late-breeding adults. Conclusion Increased frequency of intraspecific interactions experienced by late breeders in the presence of early-breeding conspecifics resulted from the kleptoparasitic activities of older chicks but was not sufficient to contribute to the observed seasonal reproductive decline at this dense breeding colony.

Individual quality, survival variation and patterns of phenotypic selection on body condition and timing of nesting in birds

Questions about individual variation in "quality" and fitness are of great interest to evolutionary and population ecologists. Such variation can be investigated using either a random effects approach or an approach that relies on identifying observable traits that are themselves correlated with fitness components. We used the latter approach with data from 1,925 individual females of three species of ducks (tufted duck, Aythya fuligula; common pochard, Aythya ferina; northern shoveler, Anas clypeata) sampled on their breeding grounds at Engure Marsh, Latvia, for over 15 years. Based on associations with reproductive output, we selected two traits, one morphological (relative body condition) and one behavioral (relative time of nesting), that can be used to characterize individual females over their lifetimes. We then asked whether these traits were related to annual survival probabilities of nesting females. We hypothesized quadratic, rather than monotonic, relationships based loosely on ideas about the likely action of stabilizing selection on these two traits. Parameters of these relationships were estimated directly using ultrastructural models embedded within capture-recapture-band-recovery models. Results provided evidence that both traits were related to survival in the hypothesized manner. For all three species, females that tended to nest earlier than the norm exhibited the highest survival rates, but very early nesters experienced reduced survival and late nesters showed even lower survival. For shovelers, females in average body condition showed the highest survival, with lower survival rates exhibited by both heavy and light birds. For common pochard and tufted duck, the highest survival rates were associated with birds of slightly above-average condition, with somewhat lower survival for very heavy birds and much lower survival for birds in relatively poor condition. Based on results from this study and previous work on reproduction, we conclude that nest initiation date and body condition covary with both reproductive and survival components of fitness. These associations lead to a positive covariance of these two fitness components within individuals and to the conclusion that these two traits are indeed correlates of individual quality.

Within-season Nest Persistence in Large Wading Bird Rookeries

Within-season nest persistence of large wading bird (Ciconiiformes) rookeries in the Atchafalaya Delta, Louisiana was examined during 1994 and 1995. A sample of rookery trees was permanently marked, and the status of 7,864 nests of ten species was followed through time. Nest construction began in early March, and some rookeries were still active into September during both seasons. Uniform nest persistence rates were calculated for each 28-day time period throughout the nesting season. Nest persistence rates per 28 days ranged from 0.00-0.96. During both years the rates tended to be lowest during the early season and increased into the late season. In 1994, nest persistence rates were significantly different, caused by the interaction of season and late nesting of White Ibis. In 1995, nest persistence rates differed significantly by season. The results call into question the value of nest counts obtained by one visit to a rookery complex, as these may greatly underestimate the numbers of breeding birds.

DOES MALLARD CLUTCH SIZE VARY WITH LANDSCAPE COMPOSITION: A DIFFERENT VIEW

We report on the relationship between Mallard (Anas platyrhynchos) clutch size and cropland area in the landscape in western Minnesota during 1997–1999. We measured clutch size in two types of nest structures and fit a mixed-effects model to the data to examine the relationship. Our model also included covariates to control for the effects of year, nest initiation date, estimated pair numbers, and nest structure type. Unique landscapes associated with each nest (n = 134) ranged from 46.4–84.8% cropland. Clutch size was unrelated to cropland area, nest structure type, and estimated number of pairs with access to structures. Mean clutch size declined with nest initiation date early in the nesting season, but increased somewhat for nests initiated after 30 May. Clutch size also differed among years. Mean clutch size, adjusted for nest initiation date, was 11.0 ± 0.19 SE for 1997, 10.5 ± 0.19 SE for 1998, and 11.0 ± 0.19 SE for 1999. Conclusions regarding the significance of the year effect and the degree of nonlinearity due to nest initiation date were sensitive to potential clutch size outliers, but cropland area had no effect on clutch size regardless of the way we constrained clutch size. Nest parasitism by philopatric females laying in certain structures might explain the observed increase in clutch size in late nest initiations.

Bacteria in starling nests

We investigated the bacterial frequency and identified 11 genera of bacteria in starling-nests of a nest box colony in southern Germany. We sampled bacteria with a new method: agar paddles, developed for the food industry, were pressed against the naked belly of nestlings at an age of 14 days for 5 seconds. The bacteria colonies on the paddle surface were counted after incubation and their numbers served as an estimate of bacterial infestation of a nest. Bacteria numbers increased with season and precipitation. No relationship between bacteria load of the nests and hatching and fledging success, nestling mortality and body mass close to fledging was detected. The reason for this may be that a high bacteria load is not necessarily harmful but may even act in a beneficial way on the digestive and immune system. Nevertheless we consider it possible that the higher load of bacteria of late nests may under certain conditions be one of the factors responsible for the frequently observed lower quality of second brood nestlings.