The symbiotic nest association of yellowfin shiners,Notropis lutipinnis,and bluehead chubs,Nocomis leptocephalus

Synopsis Yellowfin shiners spawn in nests constructed by male bluehead chubs. To determine whether yellowfin shiners are obligatory symbionts of bluehead chubs, different densities of shiners were isolated from chubs and presented with artificial nests in stream enclosures. Yellowfin shiners failed to reproduce in the absence of bluehead chubs, indicating that the symbiosis is obligatory for the shiners. Bluehead chubs tended nests by moving stones, which kept the nests free of silt. Nest tending lasted for the same amount of time that embryos and larvae of both species were found in the nests. Yellowfin shiners benefit from a protective nest and parental care given by the chub. Eggs, embryos and larvae of both species may benefit from reduced predation due to a dilution effect. These observations suggest that this nest association is an obligatory, mutualistic symbiosis.     

Replication of four aquatic reoviruses in experimentally infected golden shiners (Notemigonus crysoleucas).

Golden shiners (Notemigonus crysoleucas) experimentally infected with four reoviruses supported replication of golden shiner virus as well as chum salmon virus, reovirus 13p2 and catfish reovirus at temperatures of 23 and 28 C. All four reoviruses replicated in golden shiners in this study. Natural infections of the golden shiner virus are known only in golden shiners.     

Alternative reproductive tactics and courtship in the common goby

In the marine common goby Pomatoschistus microps , males either build nests and attract females to spawn or act as sneakers, forcing themselves into other males' nests during mating, to fertilize some of the eggs in the clutch. The reproductive tactics of small males were studied in the presence of surplus nest material and an excess of gravid females, while a larger, nestholding male spawned with a female. Of 24 small males, 13 only attempted to sneak, seven only courted females and/or spawned in their own nest, and four performed both behaviours. The small males who attracted females successfully were significantly larger than the ones who failed to do so. Females had been courting the small male more often when he subsequently spawned in his own nest, than when he did not get a female. The small males did not court the females very frequently, and their courtship rate did not depend on whether or not they attracted females. Instead, female courtship behaviour may be a cue for a male either to spawn as a nest holder or become a sneaker. The study pointed out the importance of female behaviour for male reproductive tactics, which could be more important in fish than is known currently.     

Nest‐site selection by golden plover: why do shorebirds avoid nesting on slopes?

It is widely known that many upland-breeding shorebirds tend to nest on plateaus but to date no studies have put forward explanations for this phenomenon. We examined the effect of slope and habitat on the distribution of ground-nesting golden plover Pluvialis apricaria at two study sites in County Durham, U.K. Golden plovers showed strong selection for nesting on flat ground. Habitat significantly affected nest-site location on one study site (heather burnt within the past 2 years was favoured and older stands of heather were avoided) but not on the other. Fifty-nine per cent of all nests failed. We attributed 95% of all losses to predation. Seventy-five per cent of nests, in which the predator was identified, were taken by ground predators, mainly stoats Mustela erminea . Nests on flat ground had significantly higher rates of survival than those on slopes. Nest survival did not vary significantly with habitat type nor with vegetation height or density around the nest. Neither habitat type, vegetation height nor vegetation density around nests differed between nests on slopes and on flat ground. In addition, individuals that nested on flat ground tended to have less black on their underparts (a suggested indicator of dominance). We suggest that birds nesting on slopes are less efficient at avoiding nest predation than those nesting on the flat. The nature or degree of a bird's response to a predator may be related to the efficiency of individual anti-predator responses and/or to visibility from the nest. This study cannot differentiate between these two explanations. We encourage further work to investigate differences in behaviour between individuals nesting on slopes and those on flat ground.     

Spawning patterns in the three-spined stickleback (Gasterosteus aculeatus L.): an evaluation by DNA fingerprinting

We analysed a random sample of 10 three-spined stickleback nests by DNA fingerprinting. DNA from the guardian male and a random subsample of LO fry per nest were probed with pYNZ 132, a human single-locus probe for VNTR-loci (variable number of tandem repeats). On average this probe produced DNA fingerprints of 12 scoreable bands. By comparing the bands present in each individual, we calculated band sharing indices (BSIs) between the guardian male and its fry. The BSls varied between 0.40 and 0.77 with an average (± S.D.) of 0.59 ± 0.09. We therefore conclude that the guardian male was the true father of the fry in all these nests. Once the paternal bands in each fry were determined, we compared the maternal bands among the fry of each nest. Based on the BSIs obtained with these comparisons, we found that one guardian male enticed three females to spawn in its nest, six enticed two females and three enticed one female.     

Male Nest Choice in Sand Gobies, Pomatoschistus minutus

Although material resources can have a direct bearing on the fitness of both sexes, few studies have actually examined resource-based preferences from a male choice perspective. In sand gobies, Pomatoschistus minutus , the size of a male's nest influences his attractiveness to females and also dictates the number of eggs he can receive. Thus, one might expect males to prefer larger nests. However, an earlier study of marine sand gobies from a population with a surplus of nest sites and high nest predation found that males exhibited size-assortative nest preferences. Here, we investigated male nest preferences from a brackish population characterised by a chronic nest shortage but lower predation risk. A survey of naturally settled nests in the field (shells and rocks) showed a pattern of size-assortative nest occupancy consistent with the previously studied population, with larger males occupying larger (i.e. rock) nests. However, when offered a choice of potential nests in the absence of male competition, we found that all male gobies in our population, irrespective of their own body size, actually preferred larger nests. Moreover, a predilection towards large nests superseded any preferences based on nest colour. Our results not only indicate the existence of male preferences for material resources but, considered in the light of previous work, also suggest that such preferences may vary among populations and, importantly, may not necessarily be realised in a competitive setting.     

Testing common assumptions in studies of songbird nest success

We studied Ovenbird Seiurus aurocapilla and Golden‐winged Warbler Vermivora chrysoptera populations in northern Minnesota, USA, to test two common assumptions in studies of songbird nest success: (1) that the condition of an empty nest on or near its expected fledge date is an indicator of nest fate; and (2) that the presence of a fledgling or family group within a territory confirms a successful nest in that territory. We monitored the condition of nests and used radiotelemetry to monitor juveniles through the expected fledging date and early post‐fledging period. Of nests that contained nestlings 1–2 days before the expected fledge date, fates were misidentified using nest condition alone for 9.5% of Ovenbird nests, but those misidentifications were made in both directions (succeeded or failed), yielding only a small bias in estimated nest success. However, 20% of Golden‐winged Warbler nests were misidentified as successful using nest condition during the final visit interval, biasing the nest success estimate upward by 21–28% depending on the treatment of uncertain nest fates. Fledgling Ovenbirds from 58% of nests travelled beyond their natal territory within 24 h, rising to 98% after 5 days, and those fledglings travelled up to 390 m from nests within 10 days of fledging. Fledgling Golden‐winged Warblers from 13% of nests travelled beyond their natal territory within 24 h, rising to 85% after 5 days, and those fledglings travelled up to 510 m from nests within 10 days of fledging. We conclude that nest condition and fledgling presence can be misleading indicators of nest fate, probably commonly biasing nest success estimates upward, and we recommend that these assumptions should be tested in additional species.     

Differential moult patterns in relation to antipredator behaviour during incubation in four tundra plovers

Golden plovers and Grey Plovers Pluvialis spp. all have very distinct breeding plumage rich in contrast, with a conspicuous black belly and breast bordered by a bright white fringe. Eurasian Golden Plovers are known partly to replace their breeding plumage with striped yellow feathers during incubation, different from both breeding and non-breeding plumages. In this study a similar partial breeding moult was observed in Pacific Golden Plovers and American Golden Plovers caught on the nest or collected during incubation, although the feathers did not differ clearly from those of non-breeders. This moult starts during incubation and precedes the post-breeding moult into non-breeding plumage. Because the lighter feathers reduce the contrast between the black belly and the white flanks, we suggest that during incubation the plumage characteristic that plays an important role in mate choice is no longer important; at this stage it is better for the bird to be inconspicuous. Additional information on museum skins of golden plovers and of Grey Plovers indicated that only the three golden plovers undergo this partial moult, but that Grey Plovers in general retain full breeding plumage throughout incubation. The three golden plovers also resemble each other in their generally very passive nest defence strategies. In contrast, the larger Grey Plovers actively chase and attack aerial and ground predators. Thus, a reduced conspicuousness of the body plumage during incubation is likely to benefit the golden plovers more than the Grey Plover. We suggest that nest defence behaviour, plumage characteristics and perhaps size have co-evolved as a response to different selection pressures in golden plovers and Grey Plover, but alternative hypotheses are also discussed.     

Threat-sensitive Nest Preferences in Male Upland Bullies,Gobiomorphus breviceps

A male's ability to acquire and defend a nest site against competitors is an important requirement for successful breeding in many fish species. In the upland bully Gobiomorphus breviceps (Eleotridae), not all males are successful in gaining ownership of nesting rocks; therefore, male-male competition may be important in nest acquisition. Although larger nests have the potential to hold more eggs, in nature there is a preferred nest size well below the maximum available. I found that in over 88% of dyadic contests, the larger male was successful in acquiring the single nesting site provided. When males were individually given a choice of two artificial nest rocks, they consistently preferred the larger nest. These results suggest that larger males have the ability to occupy the largest nests. In the presence of a trout predator, males preferred nests with three closed sides 93% of the time. This preference disappeared when the threat was a conspecific. This shows that while males were choosing the larger nests their decisions were also threat-sensitive.     

Mate Choice and Mating Pattern in a Stream Goby of the Genus Rhinogobius

The mate choice and mating pattern of a benthic goby Rhinogobius sp. CB (cross band type) were investigated in the Kamo River, Shikoku, Japan. During the breeding season, gravid females assumed a nuptial color and either males or females initiated a courtship display. Males preferentially courted a female of similar size to lead her to his nest, whereas females courted more frequently when they encountered a large male. Eggs in any one nest were always at the same developmental stage. Sampling data of nesting males and females indicated that, in more than half the nests, males gathered more than one female before spawning. In some nests with eggs, two or three females had spent ovaries, indicating that the eggs were laid by multiple females within a short span of time. However, a comparison between the total number of eggs which females would spawn in one nest and the number of eggs actually deposited suggested that eggs were contributed by one female in most nests. This low level of polygyny in spite of multiple female availability is attributed to a limited available spawning area of the nest.     

The importance of sperm competition risk and nest appearance for male behavior and female choice in the sand goby, Pomatoschistus minutus

To test if an increased sperm competition risk affects malebehavior and mating decisions of both sexes, we performed twoexperiments using the sand goby, Pomatoschistus minutus, a nest-buildingfish with exclusive paternal care. In our first experiment,a nest-holding male, with a confined female, was sequentiallyexposed to a vial with a sneaker male or an empty vial. Whilemale courtship, nest building, displacement fanning, and timeoutside the nest were unaffected, individual males showed ahigher mucus preparation effort inside the nest in the presenceof a sneaker male than when alone. We found such mucus to containsperm, thus clearly suggesting an importance in sperm competition.In our second experiment, a female was free to spawn with twodifferent males, one of which was exposed to a confined sneakermale. Male mating success was not affected by the presence ofa sneaker male. However, the volume of sand the male had puton his nest was positively associated with female spawning decision,while nest-opening width was not. In a partial correlation offive traits thought to attract females (nest-opening width,sand volume, male courtship display, displacement fanning, andmale size), males that fanned well were found to also buildlarge nests or display intensely, but not both. This indicatesthat rather than being jacks-of-all-trades, individual malesfocus on a subset of traits for attracting females.     

Allopaternal care in the tessellated darter,Etheostoma olmstedi (Pisces: Percidae)

Synopsis Large male tessellated darters, Etheostoma olmstedi, defend flat-bottomed rocks, the undersides of which serve as spawning substrates. Because females attach eggs directly onto bare stone, a spawning bout necessarily decreases the surface area available for further breeding at a nest. In apparent response to the female preference of ovipositing on rocks with the most bare surface, fathers abandon nests with their attached offspring to search for rocks with more uncovered surface. Egg abandonment also results after roving fathers intercept and spawn with ripe females and remain at a different rock to care for a new clutch. In essence, large males appear to maximize the number of eggs they fertilize by sequentially monopolizing breeding patches that are temporarily most desirable to females. The costs to a father of abandoning his eggs appear to be low for two reasons: (1) non-territorial males, created by a scarcity of suitable rocks, readily occupy vacant nests, and clean and aerate the abandoned eggs; and (2) after water hardening, eggs are less vulnerable to cannibalism. The maintenance of eggs by nonparental males may be both incidental to scrubbing the ceiling for their own breeding and adaptive in that viable eggs stimulate females to spawn; neither would appear to involve parental investment costs. Thus, allopaternal care in the tessellated darter may have evolved because it is performed in the selfish pursuit of spawning opportunities while entailing little, if any, of the costs normally subsumed within parental investment.     

Mating success of alternative maturation phenotypes in male Atlantic salmon,Salmo salar

Summary Mature male parr successfully fertilized eggs of anadromous female Atlantic salmon, Salmo salar, in competition with anadromous males under simulated natural conditions. Mating situations were created in which mature male parr and anadromous males competing for the opportunity to spawn with an anadromous female differed in allelic forms of the same enzyme. Females deposited eggs into a sequence of 3 or 4 eggs nests. The mean proportion of eggs in a redd fertilized by parr increased with increasing numbers of parr present at a redd, reaching 23% at male parr: anadromous male ratios of 20:1. Single male parr fertilized, on average, 5% of the eggs in a redd. The proportion of eggs in an egg nest fertilized by parr also depended upon the order of egg nest construction, such that parr mating success was highest at the initial nest constructed and lowest at the final nest. Parr have relatively high fertilization success for their size when compared with the smaller maturation phenotype of other salmonids.     

Blue tits (Cyanistes caeruleus) respond to an experimental change in the aromatic plant odour composition of their nest

Although the use of olfaction by birds is now widely recognised, the olfactory abilities of passerine birds remain poorly explored, for historical reasons. Several studies however suggest that passerines can perceive volatile compounds in several biologically relevant contexts. In Corsica, recent findings suggest that cavity-nesting blue tits may use volatile compounds in the context of nest building and maintenance. Although they build their nests mainly from moss, female blue tits also frequently incorporate fragments of several species of aromatic plants in the nest cup. In field experiments, breeding female blue tits altered their nest maintenance behaviour in response to experimental addition of aromatic plants in their nest. In aviary experiments, captive male blue tits could be trained to detect lavender odour from a distance. Here I report results from a field study aimed to test whether adult blue tits altered their chick-feeding behaviour after an experimental change in nest odour composition. I experimentally added fragments of aromatic plant species that differed from those brought in the nests before the start of the experiment in a set of experimental nests and added moss, the basic nest material, in a set of control nests. Both male and female blue tits hesitated significantly longer entering the nest cavity after addition of new aromatic plant fragments, as compared to moss addition. This response was especially observed during the first visit following the experimental change in nest plant composition. Nest composition treatment had no effect on the time spent in the nest. This study demonstrates that free-ranging blue tits detect changes in nest odour from outside the nest cavity.     

Beach erosion and nest site selection by the leatherback sea turtle Dermochelys coriacea (Testudines: Dermochelyidae) and implications for management practices at Playa Gandoca, Costa Rica

Leatherback sea turtles (Dermochelys coriacea) nest on dynamic, erosion-prone beaches. Erosive processes and resulting nest loss have long been presumed to be a hindrance to clutch survival. In order to better understand how leatherbacks cope with unstable nesting beaches, I investigated the role of beach erosion in leatherback nest site selection at Playa Gandoca, Costa Rica. I also examined the potential effect of nest relocation, a conservation strategy in place at Playa Gandoca to prevent nest loss to erosion, on the temperature of incubating clutches. I monitored changes in beach structure as a result of erosion at natural nest sites during the time the nest was laid, as well as in subsequent weeks. To investigate slope as a cue for nest site selection, I measured the slope of the beach where turtles ascended from the sea to nest, as well as the slopes at other random locations on the beach for comparison. I examined temperature differences between natural and relocated nest sites with thermocouples placed in the sand at depths typical of leatherback nests. Nests were distributed non-randomly in a clumped distribution along the length of the beach and laid at locations that were not undergoing erosion. The slope at nest sites was significantly different than at randomly chosen locations on the beach. The sand temperature at nest depths was significantly warmer at natural nest sites than at locations of relocated nests. The findings of this study suggest leatherbacks actively select nest sites that are not undergoing erosive processes, with slope potentially being used as a cue for site selection. The relocation of nests appears to be inadvertently cooling the nest environment. Due to the fact that leatherback clutches undergo temperature-dependent sex determination, the relocation of nests may be producing an unnatural male biasing of hatchlings. The results of this study suggest that the necessity of relocation practices, largely in place to protect nests from erosion, should be reevaluated to ensure the proper conservation of this critically endangered species.     

The benefit to some minnows of spawning in the nests of other species

Synopsis Fishes that act as nest associates spawn simultaneously with nest-building hosts and then abandon their eggs. The proposed benefit for this behavior is increased brood survivorship, arising from the physical environment provided by the nest or the parental care provided by the host. Field and enclosure experiments indicated that associates benefit from the parental care provided by the host, and not from the physical environment provided by the nests of hosts. This information, along with the effect of nest association on host reproductive success, is necessary before the nature of this nesting symbiosis can be characterized.     

The influence of parental care behaviour on localized nest spacing in smallmouth bass, Micropterus dolomieu

Synopsis I examined the consequence of territorial behaviour on localized nest spacing by male smallmouth bass, Micropterus dolomieu in Jones Bay, Lake Opeongo, Ontario. I compared observed nest spacing to that predicted from (i) territory size and shape measured using sonic tracking procedures; and (ii) 1000 simulated, randomly established nesting stocks. The observed spacing between nests (17.52 ± 1.46 m; mean ± standard error) was not different from that predicted from measurements of territory size and shape (17.60 ± 3.20 m) but was significantly greater than that predicted for randomly established nests (9.53 ± 0.06 m). Parental care-associated territorial behaviour influences the spacing between smallmouth bass nests.     

Elaborate Nests in a Weaverbird: A Role for Female Choice?

Studies on sexual selection have focused on behaviour and morphology, but several groups of animals build elaborate structures associated with acquiring a mate. I investigated female choice for nests built by male baya weavers (Ploceus philippinus). Nest choice by females should be strong, as nests are obvious direct benefits provided by males. I used a field experiment supplemented with correlational information to ask whether females appear to base mate choice decisions on male behaviour, nest architecture, and nest location. When the nests of highly visited males were exchanged with those of poorly visited males, female visits remained highest at the original male and location. I found no relationship between female choice and male display or other behaviour. Correlational analyses show that nest location was a better predictor of female choice than was nest architecture. These data suggest that current female choice is driven more by access to safe nesting sites rather than to well‐built nests, possibly because all males are able to build nests of adequate quality. However, nest architecture is unlikely to be irrelevant to females, and its role deserves further investigation.     

Ectoparasites,nest site choice and breeding success in the pied flycatcher

It has recently been suggested that nest box studies might bias the measurement of behavioural and life-history traits, because the removal of old nests may reduce the load of ectoparasites. This experimental artefact may have notable effects on nest site choice and breeding success in cavity-breeding birds. We tested (i) if pied flycatchers Ficedula hypoleuca prefer clean nest boxes and (ii) if old nest material affects the number of parasites and the breeding success of pied flycatchers. In the first experiment we offered birds one cleaned nest box and one nest box with old nest material from the previous year. The two nest boxes were placed in very similar sites near each other. In this experiment all pied flycatchers clearly preferred dirty nest boxes. In the second part of the study we distributed clean nest boxes and dirty ones on the same study area. After breeding was over we counted the number of fleas Ceratophyllus gallinae in the nest material. This flea species was the most abundant and probably the most hazardous parasite in the nests. Surprisingly, we found that there were significantly more fleas in the nest boxes with nests of the current year only than in the boxes with nests of both current and previous year. This might explain the preference for the dirty boxes. However, our results do not indicate that the number of fleas affects breeding success in the pied flycatcher.     

Habitat and home range fidelity in a trophically dimorphic pumpkinseed sunfish (<Emphasis Type="Italic">Lepomis gibbosus</Emphasis>) population

We investigated habitat selection in a trophically dimorphic population of pumpkinseed sunfish (Lepomis gibbosus) to determine whether littoral and limnetic ecotypes exhibit habitat or site fidelity. A transplant experiment was conducted, in which 998 pumpkinseeds captured from littoral and limnetic sites were marked and released in either the site of capture, the nearest site of the same habitat type, or the nearest site of the opposite habitat type. Daily recapture attempts over the course of the reproductive and growing season provided a 25% recapture rate, 40% of which were recaptured on multiple occasions at the same site. Site fidelity was very high in both ecotypes. Results estimated with a multi-state transition model indicated that the probability of a transplanted pumpkinseed returning to its site of origin ranged from 74% for limnetic pumpkinseeds released into a different limnetic or littoral site, to 93% for littoral pumpkinseeds released into a limnetic site. Furthermore, the probability of a pumpkinseed being recaptured at its site of origin if not transplanted was estimated at 97 and 98% for limnetic individuals and littoral individuals, respectively. Discriminant Function Analysis of helminth parasite loads sampled from littoral and limnetic individuals could classify site of origin with 96–100% accuracy, suggesting that the habitat and site fidelity patterns observed with mark–recapture are indicative of long-term habitat segregation of the two forms. The results of our experiment provide compelling evidence of correlated habitat selection as a function of home range fidelity within both ecotypes of a subtly dimorphic species. Such behaviour could have a significant effect on present or future gene flow.