Clutch Size Manipulation Research Articles

Properties of food loads delivered to nestlings in the pied flycatcher: effects of clutch size manipulation, year, and sex.

Experimental manipulation of the number of altricial offspring is supposed to modify parental expenditure in birds. In addition to the observed increase in parental feeding rate, it is also possible that the choice of prey or the size of load may change with the changing demand for food. Sexual differences in the provisioning response are also expected, on the basis of earlier studies. We examined the effect of brood size manipulation on choice of prey brought to nestlings and load size in the pied flycatcher. The composition and size of loads differed between years, possibly depending on varying availability of different prey types. Males responded to brood size enlargement by gathering heavier loads, whereas females showed no response. The alteration of load size in males was not explained by a larger number of prey items or mean prey size, but was a combination of these components. It is likely that males also increased their work rate in response to increased food demand at the nest. The absence of response in females might be because they are unable to increase work rate any further, or because food delivery rate in females can not be optimized by changing load properties.

The Costs of Incubation in the British Storm-Petrel: An Experimental Study in a Single-Egg Layer

The balance between investment in current reproduction and future survival or reproduction may be particularly important to long-lived species. Many of these species are single-egg layers for which incubation costs cannot be realistically measured by manipulation of clutch size. Here I report an experiment in which I manipulated the costs of incubation in the British Storm-petrel Hydrobates pelagicus by prolonging and shortening the incubation period by exchanging eggs between clutches with an average difference in laying dates of 9 days. Hatching success was higher in nests in which the incubation period was shortened than in nests in which it was prolonged. However, neither fledging success nor chick growth differed between treatments. Experimental manipulation of the incubation period affected laying date in the subsequent year. This finding suggests that incubation is costly in Storm-petrels and that the reproductive effort in one breeding attempt may influence reproductive decisions in subsequent breeding attemps in long-lived seabirds.

Clutch Size Manipulation in the Pied Flycatcher: Effects on Nestling Growth, Parental Care and Moult

To study parental responses during the incubation and nestling periods, nestling growth and adult moult, two eggs were either removed from or added to Pied Flycatcher Ficedula hypoleuca clutches shortly after clutch completion. Incubation period and hatching success did not differ between experimental groups. In the enlarged group the rate of male incubation feeding of the female was higher than in the other groups. Fledgling mass and tarsus length were negatively related to the experimental change in clutch size, and this effect arose entirely in the first four days after hatching. The results suggest that the embryo development during the incubation period and nestling growth during the first days after hatching are important for the subsequent nestling growth and should be taken into account when analysing the results of brood size manipulations. Fledging and breeding success, fledgling mass and tarsus length differed between experimental groups with lower values in the enlarged group. There was an effect of experimental treatment on female and male feeding rates, with higher number of feeding visits in the enlarged group. The onset of adult moult was related to calendar date and there was no effect of the experiment on the proportion of birds moulting at any given time. At least in this population, moult may not be a mechanism mediating costs of reproduction.

AN EXPERIMENTAL STUDY OF THE COSTS OF REPRODUCTION IN THE KITTIWAKERISSA TRIDACTYLA: COMMENT

EcologyVolume 78, Issue 4 p. 1284-1287 Comment AN EXPERIMENTAL STUDY OF THE COSTS OF REPRODUCTION IN THE KITTIWAKE RISSA TRIDACTYLA: COMMENT Thierry Boulinier, Thierry Boulinier Laboratoire d’Ecologie, CNRS-URA 258, Université Pierre et Marie Curie, 7 quai St. Bernard, F-75252, Paris, France. Present address: NBS, Patuxent Wildlife Research Center, Laurel, Maryland 20708, USA.Search for more papers by this authorGabriele Sorci, Gabriele Sorci Laboratoire d’Ecologie, CNRS-URA 258, Université Pierre et Marie Curie, 7 quai St. Bernard, F-75252, Paris, France.Search for more papers by this authorJean Clobert, Jean Clobert Laboratoire d’Ecologie, CNRS-URA 258, Université Pierre et Marie Curie, 7 quai St. Bernard, F-75252, Paris, France.Search for more papers by this authorEtienne Danchin, Etienne Danchin Laboratoire d’Ecologie, CNRS-URA 258, Université Pierre et Marie Curie, 7 quai St. Bernard, F-75252, Paris, France.Search for more papers by this author Thierry Boulinier, Thierry Boulinier Laboratoire d’Ecologie, CNRS-URA 258, Université Pierre et Marie Curie, 7 quai St. Bernard, F-75252, Paris, France. Present address: NBS, Patuxent Wildlife Research Center, Laurel, Maryland 20708, USA.Search for more papers by this authorGabriele Sorci, Gabriele Sorci Laboratoire d’Ecologie, CNRS-URA 258, Université Pierre et Marie Curie, 7 quai St. Bernard, F-75252, Paris, France.Search for more papers by this authorJean Clobert, Jean Clobert Laboratoire d’Ecologie, CNRS-URA 258, Université Pierre et Marie Curie, 7 quai St. Bernard, F-75252, Paris, France.Search for more papers by this authorEtienne Danchin, Etienne Danchin Laboratoire d’Ecologie, CNRS-URA 258, Université Pierre et Marie Curie, 7 quai St. Bernard, F-75252, Paris, France.Search for more papers by this author First published: 01 June 1997 https://doi.org/10.1890/0012-9658(1997)078[1284:AESOTC]2.0.CO;2Citations: 24 Present address: NBS, Patuxent Wildlife Research Center, Laurel, Maryland 20708, USA. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume78, Issue4June 1997Pages 1284-1287 RelatedInformation

Association between haematozoan infections and reproduction in the Pied Flycatcher

1. Parasites may affect breeding success of their host since they compete for the same resources as their hosts. Reproduction may also increase the susceptibility of a host to parasite infections owing to lowered resistance to parasites during breeding. 2. We studied the association between breeding performance and haematozoan parasite infection in the Pied Flycatcher (Ficedula hypoleuca) by using both natural data on reproduction and data from clutch size manipulations. 3. The most frequent blood parasites of the Pied Flycatcher in central Finland were Haemoproteus pallidus, Haemoproteus balmorali and Trypanosoma avium complex. 4. We did not find evidence that these haematozoan parasites have any debilitating effects on either reproduction or survival. The variation in reproductive effort did not seem to influence susceptibility to new blood parasite infections. 5. The intensity of Haemoproteus balmorali tended to increase in infected males as the brood size was artificially enlarged. Also, in females intensity of H. pallidus infection tended to increase with the level of clutch size manipulation. Thus, increased reproductive effort seems to debilitate the ability of Pied Flycatcher to control chronic infections. 6. Individuals with enlarged clutches/broods increased their reproductive effort at the expense of defence towards parasites. The cost of current reproduction may then be at least partly mediated by haematozoan infections.

Low male return rate due to clutch enlargements in the pied flycatcher (Ficedula hypoleuca)

:Increased investment in reproduction during current breeding event may entail future fitness costs. Even though a wide array of both theoretical and empirical work has been devoted to solve the problem of optimal reproductive rate, evidence for costs of reproduction has been equivocal. In the present study we examined the survival of pied flycatcher parents after a clutch size manipulation where we altered clutch size with one or two eggs. We monitored return rates and dispersal of parents during subsequent years after manipulation. An artificial increase in reproductive effort caused lowered return rates of males. Results on breeding dispersal did not support the explanation that observed low return rate was due to differences in dispersal. Thus, it seemed that low return rate of males with increased reproductive effort was due to lower local survival. No survival cost on females was evident, but return rate of females was too low for a proper test. An analysis on reproductive success revealed that within treatment groups the returning males tended to be more successful in their previous reproductive event than non-returning ones. These results together imply that phenotypic quality of individuals varies considerably causing fitness differences between individuals.

Post-fledging care, multiple breeding and the costs of reproduction in the great tit

In species that initiate multiple broods in a single season there is usually a trade-off between the number of young in the first brood, and the timing and occurrence of subsequent broods in the same season. The hypothesis that experimental reduction of clutch size reduces the duration of post-fledging care was tested in great tits, Parus major, and the effect of second clutches on post-fledging care was also investigated. Parental care continued for 20 days (range 10–32 days) after fledging. Investment in successive clutches overlapped, and the duration of post-fledging care was positively correlated with the inter-clutch interval. Second clutches reduced the female's contribution to post-fledging care. The clutch size manipulation did not affect the duration of post-fledging care. It is concluded that factors other than the duration of post-fledging care mediate the effect of clutch size manipulations on second clutches, and an alternative hypothesis is discussed.

Maternal behavior and clutch manipulation in the ring-legged earwig (Dermaptera: Carcinophoridae)

The expression and maintenance of maternal behavior in the earwig,Euborellia annulipes, was examined through manipulation of clutch size, age, and species and through observations of interactions between brooding females. Females underwent discrete gonadotrophic cycles culminating in oviposition of first clutches that were highly variable in size. Neither the head capsule width nor the age of the mother was correlated with clutch size. Maternal care extended through embryogenesis and for the week following hatching. Clutch removal significantly shortened the interclutch interval, indicating that the presence of brood inhibited the onset of the second gonadotrophic cycle. Brooding females readily accepted replacement clutches of the same age. Thus, mothers did not appear to distinguish their own eggs from those of other females. Experimental doubling of clutch size did not significantly reduce the proportion hatching or fledging. In contrast, reducing clutch size diminished the percentage successfully fledging. Manipulation of clutch age resulted in reduced hatching/fledging success. Placing two females, each with newly laid clutches, in the same cage usually resulted in egg transfer from the nest of one female to that of the other within 12 h. Nests of females with larger forceps were significantly more likely to contain both clutches. When mothers with first clutches were paired with mothers with third clutches, eggs were more likely to be transferred to the nest of the older female.E. annulipes females with newly laid clutches appeared to accept as replacement clutches eggs of the earwigDoru taeniatum. Alien clutches were maintained for the typical duration of embryogenesis; however, noD. taeniatum hatchlings were observed.

Clutch size manipulations in two seed beetles: consequences for progeny fitness.

Seed beetles (Coleoptera: Bruchidae) lay their eggs on discrete resource patches, such that competition among larvae for food is an important component of their biology. Most seed beetles, including Stator limbatus, lay eggs singly on individual seeds and avoid superparasitism except when seeds are limiting. In contrast, S. beali, a closely related congener, lays eggs in clutches on a single seed. We tested the hypothesis that natural selection on larval life history characters favors small clutches (selection against large clutches) in S. limbatus, but that selection against large clutches is relaxed in S. beali because of the large size of its host's seeds. We manipulated clutch size and examined its relationship to offspring fitness. Clutch size affected the survivorship of S. limbatus larvae(r 2=0.14), but had no detectable effect on the survivorship of S. beali larvae (r 2=0.04). Also, clutch size had a large effect on development time and body weight of S. limbatus, but not of S. beali. We discuss the implications of this result for the evolution of clutch size in S. limbatus and S. beali.

Clutch-Size Manipulations in the Yellow-Headed Blackbird: A Test of the Individual Optimization Hypothesis

To test the critical short-term predictions of the individual optimization hypothesis (IOH), Yellow-headed Blackbird (Xanthocephalus xanthocephalus) clutches of three and four eggs were experimentally enlarged or reduced by one egg, and broods were monitored until fledging. Predictions that control clutches would a) have greater fledging success than experimental clutches, and b) produce heavier or bigger offspring than enlarged broods were generally not supported. Within control clutches, the number of nestlings that fledged did not increase with clutch size. In fact, three-egg clutches were more productive than the most common clutch size of four eggs. The IOH appears to be unsupported for this population, at least up until the time of fledging. We suggest a potential insurance value exists for the fourth-laid egg, thus explaining the maintenance of a modal clutch size of four eggs in this species

Are Large Clutches Costly to Incubate: The Case of the Pied Flycatcher

The costs of incubation were studied in a population of Pied Flycatchers Ficedula hypoleuca both by gathering non-manipulative data and performing clutch size manipulations in three successive seasons. Enlarging clutch size caused a prolonged incubation and increased hatching failures in every year. The length of incubation did not differ between control and reduced clutches but was extended by 0.8 d in enlarged clutches. The manipulation of clutch size did not affect the weight of incubating females. However, in 1993 the incubation weight of females was negatively correlated with the length of incubation. Adverse spring weather most likely caused the many abnormalities and failures during incubation in 1993. Seven females disappeared and three dead females were found in nest-boxes during the incubation period. Moreover, in six nests one or two eggs were rolled to the rim of the nest cup presumably by the incubating female. All these observations suggest that incubation might be an energetic bottleneck for breeding and thus could be a contributory factor in the determination of clutch size in this species.

A Trade-Off Between Current Reproduction and Moult in the Pied Flycatcher- an Experiment

1. Mechanisms causing costs of reproduction in birds are poorly understood. Here we focus on the renewing of feathers (= moult) which may be a possible physiological link between successive breeding attempts. 2. We performed clutch size manipulations to study whether the reproductive effort of the Pied Flycatcher (Ficedula hypoleuca) has any effect on the initiation and progress of the moult in the late nesting period. 3. The absolute timing of breeding did not affect the onset of parents' moult, i.e. latebreeding individuals did not start moulting before nestlings were fledged more frequently than early ones. This indicates that moult was closely related to the breeding schedule of each individual bird. 4. The timing of moult was both sex and age related. Males and young birds were more likely to start moulting during the nestling period than females and older birds. 5. Both females with large original clutches and females with enlarged clutches delayed the onset of moult. This suggests a brood size-dependent regulation of moult. 6. We suggest that a trade-off between moult and current reproduction could be one possible mechanism causing costs of reproduction in birds.

Effects of clutch size manipulations on reproductive behaviour and nesting success in the cooperatively breeding Bell Miner (Manorina melanophrys)

An experimental manipulation of clutch size was carried out on a wild population of the cooperatively breeding Bell Miner (Manorina melanophrys, Meliphagidae) to assess which factor(s) limit clutch size in this species. Results provide some support for the ‘trade-off hypothesis’ since there is a cost of reproduction for the breeding female in terms of loss of body mass. The breeding female performs most of the nestling care. Clutches of three eggs are also laid during the mid-breeding season which is the period most favourable for breeding (i.e. nestlings grow faster). This evidence also supports the ‘intrabrood competition hypothesis’. Clutches that have lost an egg were more likely to be deserted; this may be an antipredator strategy since partial clutch predation has been recorded in the field. Nest predation was high in this study (64.9%), suggesting that many small clutches may be a strategy to decrease the effect of nest predation on reproductive success over the whole breeding season (‘nest predation hypothesis’). Both the ‘trade-off hypothesis’ and the ‘nest predation hypothesis’ may apply in this case since they are not mutually exclusive. The size of the attending group did not greatly affect reproductive success in the short term, although if both age structure and size of the group are taken into account, reproductive success can be better predicted.

Ectoparasites Increase the Cost of Reproduction in their Hosts

Parasites are hypothesized to increase the cost of reproduction in their hosts due to their time and energy drain. I experimentally studied the effects of the haematophagous tropical fowl mite (Ornithonyssus bursa, Berlese (Macronyssidae, Gamasida)) on the within-season costs of reproduction in their swallow (Hirundo rustica L.) hosts by simultaneously manipulating (i) the size of first clutches (which were either increased by one egg, kept as a control, or decreased by one egg), and (ii) the mite loads of first clutch nests (nests were either sprayed with a pesticide or kept as controls). The experimental treatments were successful as evidenced from the effect of the clutch size manipulation on clutch and subsequent brood size, and from the effect of the parasite manipulation on subsequent mite loads

Proximal mechanisms of the sex ratio and clutch size responses of the wasp Nasonia vitripennis to parasitized hosts

Female Nasonia vitripennis lay fewer eggs and increase the proportion of male offspring when ovipositing in hosts that have been previously parasitized compared with unparasitized hosts. This study examines the location and nature of the cues that females use in these clutch size and sex ratio decisions. Neither the sex ratio nor the clutch size response relies on chemical cues on, or a hole drilled in, the outer shell of the host (the puparium). Rather, the cues for both responses appear to be associated with the host pupa. Females manipulate clutch size but not sex ratio in response to host death: the number of eggs laid on dead hosts is significantly lower than on either live hosts or previously parasitized hosts. In addition, the cues that females use for sex ratio manipulation, but not for clutch size manipulation, are local: sex ratio cues are not detected from the end of the host that is opposite the site of parasitization; clutch size cues are. The cues that females use may constrain their sex ratio and clutch size manipulation abilities.

Experiments on clutch size and nest size in passerine birds.

Results of experiments on three passerine species suggest that brood size may be constrained by nest size, since the breeding success of pairs provided with large nestcups was greater than that of those provided with small artificial nestcups. These results may have important implications, e.g. to the design of experiments involving manipulation of clutch and brood size. A small nestcup is requisite for successful hatching during the incubation period, but a large one for successful rearing during the nestling period. In nature this difference may select for types of nesting materials that are elastic, such as mosses and lichens. However, experiments showed that such materials rapidly absorb rainwater but only slowly dry out. In addition, because large nests dry out more slowly than small nests, selection will favour small nests among those open-nesting species that have exposed nests. A further possible nest size constraint on open-nesters is nest predation. However, no difference in the predation rate was found in experiments with small and large artificial nests.

An experimental manipulation of clutch and brood size of White‐rumped Swiftlets Aerodramus spodiopygius of Fiji

By monitoring hatching success, chick growth and fledging success in normal sized and experimentally enlarged clutches and broods of the White rumped Swiftlet Aerodramus spodiophygius in Fiji this paper demonstrates the inability of this species to raise more young than is normal.

Parental energy expenditure: a proximate cause of helper recruitment in the pied kingfisher (Ceryle rudis)

Energy expenditure of adult Pied Kingfishers was measured with doubly-labeled water. Results were related to reproductive success of parents aided and unaided by helpers. Energetically stressed parents in a colony with poor food supply accepted potential helpers more often than unstressed birds in another colony where food was easily available. This treatment of helpers was reversed in both colonies through experimental manipulation of clutch size and hence energetic stress. Results are discussed in relation to the costs and benefits that helpers incur on the parents' fitness.

The Evolution of Egg Clustering by Butterflies and Other Insects

On met en evidence le fait que la ponte en grappes chez de nombreux lepidopteres (et d'autres insectes) a evolue en reponse a la selection pour une fecondite accrue