Early Nests Research Articles

The role of territory settlement, individual quality, and nesting initiation on productivity of Bell's vireos Vireo bellii bellii

Variation in habitat quality among territories within a heterogeneous patch should influence reproductive success of territory owners. Further, territory settlement order following an ideal despotic distribution (IDD) should predict the fitness of occupants if territory selection is adaptive. We recorded settlement order and monitored nests in territories occupied by individually marked Bell's vireos Vireo bellii bellii across a range of shrubland habitats in central Missouri, USA. We used an information theoretic approach to evaluate multiple hypotheses regarding the relationship between territory settlement order and seasonal territory productivity (productivity), which we define as the number of young fledged from all nest attempts in a territory. Territory settlement order and arrival date were not analogous and later arriving males displaced early settlers in 13 of 49 territories. Settlement order and lay date together were the best predictors of a territory's productivity; productivity decreased 2.08 young from earliest to latest settlement rank and lay date. Males that defended the same territory in successive years occupied territories with earlier settlement dates, but we found little evidence that age or prior ownership influenced productivity. Territory selection by male Bell's vireos was adaptive because males preferred to settle in territories that had high seasonal offspring production, but even though settlement rank was linked to territory quality, high productivity was only realized on high quality territory when also linked to early nest initiation date. While settlement rank was related to territory quality, obtaining a high quality territory had to be combined with early nest initiation to maximize productivity. We found support for the IDD hypothesis because the highest quality territories, (i.e. most productive), were settled earlier. Research that identifies high quality habitat by linking individual fitness with habitat characteristics may elucidate the importance of habitat quality, individual experience and temporal factors to productivity of Bell's vireos.

Age‐specific survival and recruitment of piping ploversCharadrius melodusin the Great Lakes region

Juvenile survival and age at first breeding (i.e. recruitment) are critical parameters affecting population dynamics in birds, but high levels of natal dispersal preclude measurement of these variables in most species. We used multi‐state capture–recapture models to measure age‐specific survival and recruitment probabilities of piping ploversCharadrius melodusin the Great Lakes region during 1993–2012. This federally endangered population is thoroughly monitored throughout its entire breeding range, minimizing concerns that measures of survival and recruitment are confounded by temporary or permanent emigration. First‐year survival (± SE) averaged 0.284 ± 0.019 from mean banding age (9 d) and 0.374 ± 0.023 from fledging age (23 d). Factors that increased first‐year survival during the pre‐fledging period (9–23 d) included earlier hatching dates, older age at banding, greater number of fledglings at a given site, and better body condition at time of banding. However, when chicks that died prior to fledging were excluded from analysis, only earlier hatching dates improved first‐year survival estimates. Females had a higher probability (0.557 ± 0.066) of initiating breeding at age one than did males (0.353 ± 0.052), but virtually all plovers began breeding by age three. Adult survival was reduced by increased hurricane activity on the southeast U.S. Atlantic coast where Great Lakes piping plovers winter and by higher populations of merlinsFalco columbarius. Mean annual adult survival declined from 1993 to 2012, and did not differ between males and females. Enhanced body condition led to higher survival to fledge and early breeding led to improved first‐year survival; therefore, management actions focused on ensuring access to quality feeding habitat for growing young and protecting early nests may increase recruitment in this federally endangered population.

Two song categories in the Canada Warbler (Cardellina canadensis)

ABSTRACT. North American wood-warbler species (Parulidae) studied to date have song systems of one or two categories. Those with two categories use them in different temporal and behavioral contexts, which suggests similar functions across species. We conducted the first detailed analysis of the vocal behavior of a species in the genus Cardellina, the Canada Warbler (C. canadensis). We found that males had two performance-encoded song categories, Mode I and Mode II, and used them in contexts similar to those in which parulids of the genera Vermivora, Mniotilta, and Setophaga use their song categories. Males sang Mode I more often during the day, when unpaired, during early nesting, and when alone or near a female. Males sang Mode II at dawn, after pairing, during the postfledging period, and when near another male. In Mode I, males sang more stereotyped songs more slowly and regularly. In Mode II, males sang more variable songs rapidly, with a more variable rhythm, and chipped frequently between songs. Al...

Leonardo fossil sketch may depict early nests

A network of burrows formed half a billion years ago may may push back parenting by 200 million years.

Unusually early nest building by Imperial Eagles (Aquila heliaca)

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Population ecology of breeding Pacific common eiders on the Yukon‐Kuskokwim Delta, Alaska

Les populations d'Eiders a duvet du Pacifique (Somateria mollissima v-nigrum) ont decline de 50-90% sur le delta du Yukon-Kuskokwim (DYK) dans l'ouest de l'Alaska entre 1975 et 1992 puis se sont stabilisees avec des faibles effectifs depuis le debut des annees 1990 jusqu'a aujourd'hui. Nous avons etudie les processus sous-jacents qui affectent la dynamique de ces populations en recoltant et en analysant les donnees demographiques des Eiders a duvet du Pacifique a 3 sites sur le DYK (1991-2004) pour un total de 29 site-annees. Nous avons examine la variation des parametres de la reproduction, teste des hypotheses concernant l'influence de certains facteurs ecologiques specifiques sur les traits d'histoire de vie et evalue leur contribution relative a la dynamique de la population locale. Le succes reproducteur etait faible et variable, tant pour un meme individu qu'entre les individus alors que la survie apparente des femelles adultes etait elevee et peu variable (0.89 ± 0.005). Tous les parametres reproductifs variaient entre les sites d'etude et les annees. Les dates d'initiation des nids s'etalaient du 4 mai au 28 juin, avec un pic (mode) d'initiation le 26 mai. Les femelles qui nichaient a un site insulaire initiaient toujours leurs nids 3-5 jours plus tot que les femelles nichant a 2 autres sites situes sur la terre ferme. La variance de la date d'initiation des nids pour la population etait negativement liee au pic suggerant une synchronisation accrue durant les annees plus tardives. En moyenne, la taille de ponte totale (pondue) variait entre 4.8 et 6.6 oeufs et declinait avec la date d'initiation du nid. En tenant compte de la predation partielle et des oeufs non-viables, le nombre moyen d'oeufs a l'eclosion variait entre 2.0 et 5.8. Pendant la saison de reproduction, la probabilite de survie journaliere (PSJ) des nids etait plus faible durant la ponte et pour les nids inities tardivement. L'estimation de la survie des nids variait considerablement entre les sites et les annees (moyenne = 0.55, ecart: 0.06-0.92), mais la variance du processus de la survie des nids etait relativement faible (0.02, IC: 0.01-0.05), indiquant que la majorite de la variance etait attribuable a l'erreur d'echantillonnage. Nous avons trouve que l'effet des observateurs pouvait reduire le succes global des nids de 0.0 a 0.36 a travers les site-annees. Les sites d'etude avec de plus faibles nombres d'echantillons et les plus frequemment visites semblaient subir un plus grand effet des observateurs. En general, les Eiders a duvet du Pacifique demontraient une grande variance dans leurs parametres de reproduction. Des tailles de ponte plus elevees et une survie des nids elevee pour les pontes initiees tot suggerent une selection directionnelle pour une nidification hâtive. Cependant, les effets environnementaux stochastiques peuvent masquer la reponse a cette force de selection. Nos resultats demontrent que les femelles qui se reproduisent tot en saison ont la plus grande valeur reproductive car elles pondent plus d'oeufs et ont la plus grande probabilite de les amener a eclosion. Nous avons developpe des modeles matriciels stochastiques structures en classes de stades qui incluent la variance spatio-temporelle observee (processus) et la co-variation des indices demographiques puis avons projete la distribution stable des classes de stades (w) et le taux de croissance de la population (X)

Long-term patterns in egg mortality during incubation and chick mortality during rearing in three species of tits in an English woodland

Capsule Mortality from egg-laying to fledging is species-dependent with Great Tits exhibiting greater losses of chicks, Coal Tits greater losses of eggs and Blue Tits exhibiting comparable rates of mortality of eggs and chicks. Aims To determine whether reproductive losses during incubation and chick-rearing were different and to ascertain whether there were different effects in three closely related songbirds. Methods Breeding success of Great Tits Parus major, Blue Tits Cyanistes caeruleus and Coal Tits Periparus ater at Treswell Wood, Nottinghamshire, England was examined, selecting only those nests which fledged at least one chick. Mortality during incubation (i.e. loss of eggs) or rearing (i.e. loss of chicks) was recorded per nest and annual means were calculated and used in the analysis, which examined relationships between year, first-egg date and species. Key factor analysis was used to investigate the relative effects of egg or chick losses on the total breeding mortality. Results Timing of reproduction showed a long-term trend to earlier nesting, but there was considerable variation from year to year in first-egg date. In this location there has been a long-term decline in clutch size in all three species. Previously unseen differences between these three species of tit are shown for mortality at different stages of the reproductive process. Coal Tits suffer the greatest losses through unhatched eggs, whereas Great Tit failures are greater during chick-rearing. Blue Tits exhibited problems in achieving success in both incubation and rearing. Conclusion Closely related tit species living in close proximity exhibit different patterns of reproductive mortality during breeding.

Possible contribution of position in the litter huddle to long-term differences in behavioral style in the domestic rabbit

Many aspects of an animal's early development might potentially contribute to long-term individual differences in physiology and behavior. Here we asked whether differences among littermates of the domestic rabbit in the position in the litter huddle that they occupy during the early nest period might contribute to the development of distinct behavioral and physiological phenotypes. In each of 12 litters we determined the pup occupying the most peripheral, the most central, and an intermediate position in the huddle during the first postnatal week. We then tested the responses of these same individuals as nestlings, juveniles and young adults when confronted by a range of age-appropriate environmental challenges. Two behavioral tests appeared particularly discriminatory in identifying differences associated with early position in the huddle; latency of pre-weaning pups to jump down from a shelf, and the response of young adults to the fearful screams of a conspecific. In both cases animals that had occupied the periphery of the huddle showed behavioral responses indicative of a more proactive behavioral style than their “intermediate” or “central” littermates. We conclude that while consistent long-term differences in behavioral style associated with early position in the litter huddle exist in rabbits, future work is needed to confirm the causal nature of this association, to identify underlying mechanisms, and to refine methods of behavioral and physiological testing across the life span.

Early nest emergence of females parasitised by Strepsiptera in protandrous bees (Hymenoptera Andrenidae)

Stylopised (= parasitised by Strepsiptera Stylopidae) imagoes of Andrena (Hymenoptera Andrenidae) bees are known to exhibit intersexual morphology. Until now, their abnormal morphology has been thought to result from undernourishment of parasitised larvae during development. This hypothesis, however, dos not fit to mass provisioning Hymenoptera. We hypothesised that induced changes in the suite of morphological characters might be a consequence of manipulation of sex-specific behavioural traits by a strepsipteran parasite. Thus, the masculinised morphology of stylopised females might be connected with shifts in their sexual behaviour. Here, we tested the effect of Stylops (Strepsiptera Stylopidae) infection on the timing of spring nest emergence in Andrena bees, where males generally emerged conspicuously earlier than conspecific females. We used two independent data samplings – pan trapping and direct observation – to avoid possible bias caused by one of the methods. In accordance with our hypothesis, we documented that the time of emergence/activity in stylopised females follows the temporal trend of uninfected, protandrous males. We ascribe this observation to host manipulation and briefly discuss the potential adaptive value of the altered host behaviour for the parasite. We discuss our results across three species: Andrena strohmella, A. minutula and A. vaga.

Effects of breeding date and weather on nestling development in White Storks Ciconia ciconia

Capsule Chick growth rate was affected by air temperature and precipitation independent of the time of breeding. Aim To investigate how the time of breeding, sibling competition and weather conditions influence White Stork nestlings’ growth rate. Methods Chick development was determined by data on the length of bill, tarsus, wing, primary flight-feathers and body mass. Data were gained from 446 inspections of 50 nests during five breeding seasons at a site in Western Poland. Results The growth rate of chicks was different in particular years of the study and was affected by air temperature and precipitation. There was no effect of sibling competition, hatching asynchrony and time of breeding on chick development. Conclusions Birds that start breeding later have fewer offspring. However, chicks from early and later nests grow at the same rate. This similarity of growth rate is important because storks leave for wintering grounds in flocks which means that the development of chicks in the population has to be synchronized.

Local breeding experience and the reproductive performance of Tree Swallows

The potential advantages of repeated breeding at a particular location should improve reproductive performance in lone-lived species of birds. However, for short-lived species, natural selection should favor individuals that most quickly develop competency in reproduction. Therefore, we hypothesized that local breeding experience beyond the first breeding attempt at a particular location would have little effect on subsequent reproductive performance of Tree Swallows (Tachycineta bicolor), a species where about 50% of adults breed only once in their lives. We tested this hypothesis using data collected from Tree Swallows in Michigan from 1993 to 2002. Because we were specifically interested in examining the effects of local breeding experience on reproductive performance, we restricted our analyses to after-second-year (ASY) females and their mates that we first encountered as breeders. Consistent with our hypothesis, we found no relationship between repeated local breeding experience and the reproductive performance of ASY female Tree Swallows and their mates as measured by clutch size and number of fledged young. However, pairs with more combined total local experience tended to lay eggs earlier in the season. These results suggest that Tree Swallows may benefit from breeding site fidelity, not because repeated local experience improves reproductive performance as measured by the production of fledglings, but because returning individuals acquire nest cavities earlier and are able to begin breeding earlier, providing time to renest in case of early nest failure.

Using logistic regression models to predict breeding success in male Adélie penguins (Pygoscelis adeliae)

Measures of breeding success are traditionally derived using the proportion of total nests that successfully reach strategic stages across a breeding season, such as pair formation, egg laying or fledging chicks. The use of logistic regression has recently become a popular tool in avian literature for identifying influential factors that predict nest and/or individual breeding success. In this study, we use logistic regression models to assess the importance of a range of factors affecting male Adelie penguin (Pygoscelis adeliae) breeding success during the 2002–2003 austral summer, when the presence of icebergs and extensive sea-ice meant overall breeding success of Adelie penguins was low (16/51 focal males had chicks reach fledging point). Logistic regression models for the early breeding season showed that good/average nest quality and central/middle nest location within the sub-colony were the best predictors of successful pair formation. Later, during incubation, the most successful males were those that not only returned earlier but were also heavier upon arrival and built nests of at least average quality. During the final stage when chicks had begun to fledge, the combined parameters of heavier male weight, early arrival time and good nest quality were the best predictors of breeding success. The logistic regression approach used here showed that the predictive ability of these parameters varied as the season progressed. However, most importantly, our logistic models fit the data well across all breeding stages.

Can cat predation help competitors coexist in seabird communities?

On oceanic islands, nest site availability can be an important factor regulating seabird population dynamics. The potential for birds to secure a nest to reproduce can be an important component of their life histories. The dates at which different seabird species arrive at colonies to breed will have important consequences for their relative chances of success. Early arrival on the island allows birds to obtain nests more easily and have higher reproductive success. However, the presence of an introduced predator may reverse this situation. For instance, in the sub-Antarctic Kerguelen archipelago, early arriving birds suffer heavy predation from introduced cats. Cats progressively switch from seabirds to rabbits, since the local rabbit population starts to peak after early arriving seabird species have already returned to the colony. When late-arriving birds arrive, cat predation pressure on seabirds is thus weaker. In this paper, we investigate the assumption that the advantage of early nest mnopolization conferred to early arriving birds may be counterbalanced by the cost resulting from predation. We develop a mathematical model representing a simplified situation in which two insular seabird species differ only in their arrival date at the colony site and compete for nesting sites. We conclude that predation may ensure the coexistence of the two bird species or favor the late-arriving species, but only when seasonal variations in predation pressure are large. Interestingly, we conclude that arriving early is only favorable until a given level where high reproductive success no longer compensates for the long exposure to strong predation pressure. Our work suggests that predation can help to maintain the balance between species of different phenologies.

Habitat use, distribution and breeding ecology of the globally threatened Rudd's Lark and Botha's Lark in eastern South Africa

Habitat use and breeding ecology of the threatened and poorly known Rudd's Lark Heteromirafra ruddi were studied in south-eastern Mpumalanga, South Africa, from October 2002 to April 2004. Data were also collected incidentally on the equally poorly known Botha's Lark Spizocorys fringillaris. Rudd's Larks establishing territories at the start of the summer breeding season selected grassland of lower than average height. Although grass in these territories had reached average height by the late breeding season, grassland selected by birds could still be distinguished from unoccupied grassland using a combination of other habitat variables. Botha's Lark was encountered less frequently than Rudd's Lark, but was always encountered along transects that also held Rudd's Lark, indicating a degree of overlap in habitat selection. However, the two species appeared to differ in nest site selection; Rudd's Lark nests were most frequently built in unburned grass and Botha's Lark nests on recently burned land. First egg dates of 93 Rudd's Lark nests ranged from late October to late March, with peak laying in January and February. Most clutches were of three eggs, and both incubation and nesting periods appear long for a lark, at 13–14 d and 13 d, respectively, for both species. Average nesting success, estimated using an extension of the Mayfield method, was around 30%, but showed a significant decline as the breeding season progressed and was lowest during the peak nesting period. Clutch size was significantly smaller in Botha's Lark (median = 2) and nesting took place significantly earlier, largely on land recently burned. Botha's Larks largely abandoned the study area after a short and possibly curtailed breeding season. Predation was the main cause of nest loss in both species and examination of the remains of dummy eggs identified mongooses, rodents and snakes as the main predators. Late burning of grassland might shorten the potential breeding season of Rudd's Lark and lead to a peak of nesting that coincides with high predator numbers. The earlier nesting of Botha's Lark suggests that this species may have been even more severely affected by a shortening of the breeding season. A model of Rudd's Lark potential distribution confirms previous suggestions that there might be a population of the species in the north-eastern Free State and identifies possible new sites elsewhere.

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 ...

Do long-term changes in sea surface temperature at the breeding areas affect the breeding dates and reproduction performance of Mediterranean loggerhead turtles? Implications for climate change

Global climate change is likely to have an important influence on the phenology, behaviour and population dynamics of many species. We investigate climatic related changes in the breeding phenology of Mediterranean loggerhead marine turtles Caretta caretta over a 19 year period and the potential relationship between these changes and reproductive success and performance. We found that the studied population has experienced fluctuating sea surface temperatures (SST) with an increasing trend during the last century. With increasing spring SST there is a trend towards earlier nesting. However, there is no significant relationship between SST and nesting season, defined as the duration between the first recorded emergence and the last nest laid. Our analyses indicate that marine turtles display phenological changes, and thus maintain favorable thermal conditions at the nesting sites. Furthermore, increasing spring SST was correlated with decreasing clutch size and increasing hatching success that resulted in an apparent lack of correlation between SST and hatchling production. This apparent independence might be misleading since it only holds for a limited range of SST values. Thus, if we estimate the effect of climate change on loggerhead population growth as neutral, based on the apparent independence between SST and total number of hatchlings, we will be underestimating the population extinction risk.

Early nesting does not result in greater productivity in the multi-brooded Woodlark Lullula arborea

Capsule Birds that started nesting early and made more nesting attempts did not produce more fledglings or recruits. Aims To investigate seasonal trends in reproductive performance of a multi-brooded ground-nesting passerine, and whether re-nesting compensates for loss of productivity to nest predation. Methods Nesting was observed in a Woodlark population breeding on heathlands in Dorset, southern England. Clutch and brood size, hatching success, chick weights, nestling starvation, fledging success and recruitment rates were compared between successive nests of individual females. Results There was a mid-season peak in clutch size, but no seasonal differences in most reproductive parameters. However, proportionally more juveniles that fledged from early nests were recruited into the breeding population. Conclusion Individuals that started nesting earlier had more nesting attempts. However, although such individuals are expected to achieve higher average annual fledging success and to contribute more recruits, neither effect was significant in a sample of 29 and 46 territories over two years, due to high levels of stochastic nest losses through predation.

Egg losses and nest desertion in Greater Rheas Rhea americana

Avian nest desertion should occur when the cost of attending the nest results in a reduction of parental fitness. In Greater Rheas Rhea americana, the male incubates the eggs so that the decision to desert the nest is made exclusively by him. Because of constraints, the timing of desertion may affect the possibility of renesting. We estimated nest desertion rates through the breeding season and at different stages of the nesting cycle (laying and early, mid- and late incubation). We also analysed the effect of egg losses at different stages of the nesting cycle on the probability of deserting the nest. Nest desertion rates decline throughout the breeding season. The probability of deserting the nest was higher during the laying stage and decreased through incubation. For all stages, egg losses were higher in nests that were deserted than in nests that were still active at the end of the corresponding stage. Egg losses were less likely to elicit nest desertion as incubation advanced. Egg losses in experimental (unattended) nests were not random. We postulate that egg losses during the first stages of the nesting cycle would be a good predictor of future egg losses and risk of nest failure. As females remain associated with the male during egg-laying and because incebation in rheas is an energetically costly activity that may affect renesting attempts, early nest desertion could increase a male's ability to remate and renest.

Genetic relatedness in early associations ofPolistes dominulus: from related to unrelated helpers

Indirect benefits obtained through the reproduction of relatives are fundamental in the formation and maintenance of groups. Here, we examine the hypothesis that females of the temperate paper wasp Polistes dominulus preferentially form groups with close relatives. Genetic relatedness data were obtained for 180 groups of females collected at the early stages of the nesting cycle of a large population of P. dominulus in two sites in southwestern Spain. Average within-group relatedness values ranged from 0.189 to 0.491. Foundresses on early nests were significantly more closely related than females in winter aggregations or in stable groups (just before workers emerged). Within-group relatedness values were independent of group size. The vast majority of worker-producing nests (c. 85%) had one or more females that were unrelated (or distantly related) to the remaining members of the group. These results provide further support to the hypothesis that indirect fitness benefits alone are unlikely to explain why P. dominulus foundresses form cooperative associations.

Reproductive success increases with group size in cooperative carrion crows, Corvus corone corone

The effect of group size and the number of helpers on reproductive success is crucial to understand the evolution and maintenance of cooperative breeding. In northern Spain, carrion crows form kin-groups (three to nine individuals) where up to five individuals contribute to rearing the young. Using data from 99 different territories, followed over 10 years, we showed that group size was positively correlated with the annual number of fledglings produced, after controlling for the potential confounding effect of territory quality. This occurred through: (1) an increased probability for larger groups of renesting after early nest failure; (2) a higher probability of nest success; and (3) a higher number of fledglings produced in successful attempts. Video-recorded observations at the nests showed that chicks received more food in larger groups during the first 10 days of life, when the risk of starvation is highest, suggesting a role of allofeeding by additional carers in augmenting the reproductive success of a group. In crows, indirect and direct benefits through increased production of young are therefore available to nonbreeding group members.