Brood Egg Research Articles

Evolutionary relationships among squids of the family Gonatidae (Mollusca: Cephalopoda) inferred from three mitochondrial loci

The oceanic squid family Gonatidae (Mollusca: Cephalopoda) is widely distributed in subpolar and temperate waters, exhibiting behavioral and physiological specializations associated with reproduction. Females of several species undergo muscular degeneration upon maturation; origins of this complex morphogenic change are unknown, hindering our understanding of ecological and morpho-physiological adaptations within the family. To provide further information regarding the evolutionary relationships within Gonatidae, three mitochondrial loci (12S rRNA, 16S rRNA, and cytochrome c oxidase subunit I) were analyzed for 39 individuals representing fourteen gonatid and six outgroup cephalopod species. In addition to elucidating relationships among gonatids, molecular data provided more information than morphological data for problematic specimens. Although some data sets are incongruent or have low nodal support values, combined molecular analysis confirms the presence of gonatid groups previously established by morphological characteristics (i.e., possessing radular teeth in seven longitudinal rows and muscular mantle tissue). These characteristics are basal to taxa possessing radular teeth in five longitudinal rows and less muscular mantle tissue, indicating that the derived forms are those species exhibiting physiological adaptation such as tissue degeneration upon maturation and egg brooding.

Reproductive Ecology and Operational Sex Ratio of Worm Pipefish(<i>Nerophis lumbriciformis</i>) in Irish Waters

Worm pipefish (Osteichthyes, Syngnathidae) are common members of the ichthyofaunal commu nity on rocky shores in western Europe. However, there has been little research into their biology and ecology. Male Nerophis lumbriciormis, like all syngnathids, brood eggs to hatching on a modified area on their abdomen. Worm pipefish are engaged in reproductive activity from January to October. During this period approximately two-thirds of the mature fish are capable of reproduction. Egg-beanrng males carry a mean of 49.5 eggs (SE + 1.4) in each brood. Male reproductive potential is dependent on the resources available to female pipefish for the generation of oocytes (clutch). While there was no significant difference in the median numbers in broods or clutches, the number of oocytes in female ovaries (55.17+ 1.77 (SE)) exceeds mean brood size. It is hypothesised that female pipefish are capable of mating with more than one male. The operational sex ratio (ratio of available males to females) from April to June is heavily biased towards female pipefish. Therefore, male pipefish become a reproductively-limiting resource for females during these months.

Reproductive Ecology and Operational Sex Ratio of Worm Pipefish (Nerophis lumbriciformis) in Irish Waters

Worm pipefish (Osteichthyes, Syngnathidae) are common members of the ichthyofaunal community on rocky shores in western Europe. However, there has been little research into their biology and ecology. Male Nerophis lumbriciformis, like all syngnathids, brood eggs to hatching on a modified area on their abdomen. Worm pipefish are engaged in reproductive activity from January to October. During this period approximately two-thirds of the mature fish are capable of reproduction. Egg-bearing males carry a mean of 49.5 eggs (SE ± 1.4) in each brood. Male reproductive potential is dependent on the resources available to female pipefish for the generation of oocytes (clutch). While there was no significant difference in the median numbers in broods or clutches, the number of oocytes in female ovaries (55.17 ± 1.77 (SE)) exceeds mean brood size. It is hypothesised that female pipefish are capable of mating with more than one male. The operational sex ratio (ratio of available males to females) from April to June is heavily biased towards female pipefish. Therefore, male pipefish become a reproductively-limiting resource for females during these months.

Reproduction and Sexual Dimorphism of the Palaemonid Shrimp Macrobrachium Hainanense in Hong Kong Streams

Macrobrachium hainanense is a large palaemonid shrimp (total length up to |$7\;{\rm{cm}}$|⁠) present at high densities (⁠|$ \gt 2$| individuals |${{\rm{m}}^{ - 2}}$|⁠) in pools of low-order forested streams in Southern China. The present study investigated the reproductive biology and sexual dimorphism of this shrimp in Tai Po Kau Forest Stream (TPK) and Tai Shing Stream (TSS), Hong Kong. Recruitment occurred during the wet season (May to August). Macrobrachium hainanense, a truly freshwater species, has abbreviated larval development, and the study populations had smaller broods than euryhaline species of this genus. Most females probably produced only a single brood of |$20 - 75$| eggs each breeding season. They showed no size-specific fecundity. Egg development in the laboratory took over 53 days, and eggs grew larger during development. The reproductive output (RO) of females was |$11\% $| for each brood, lower than for most other species of Macrobrachium. Lifetime RO was |$21\% $|⁠, assuming a single brood in each of two seasons. The population male-biased sex ratio was 1.7:1, although the size-specific sex ratio was 1:1. Females reached maturity at |$15 - 17\;{\rm{mm}}$| carapace length (CL) while males matured later at |$18 - 22\;{\rm{mm}}\;{\rm{CL}}$|⁠. Females bred at two and three years of age, while males bred three times at two, three, and four years. Interstream variation in size at onset of sexual maturity was found, with shrimps at TPK maturing later than at TSS. Discriminant Analysis revealed that mature males and females were distinct in their abdominal depths and carapace lengths with females having deeper abdomens (for egg brooding) and smaller carapaces. Juvenile males could be distinguished from females by the presence of the appendix masculina. The minimum lifespan for females of M. hainanense was approximately 29 months and for males, 48 months. Competition for females may be responsible for the longer lifespan and larger size at maturity of males.

Unpredictable food supply modifies costs of reproduction and hampers individual optimization.

Investment into the current reproductive attempt is thought to be at the expense of survival and/or future reproduction. Individuals are therefore expected to adjust their decisions to their physiological state and predictable aspects of environmental quality. The main predictions of the individual optimization hypothesis for bird clutch sizes are: (1) an increase in the number of recruits with an increasing number of eggs in natural broods, with no corresponding impairment of parental survival or future reproduction, and (2) a decrease in the fitness of parents in response to both negative and positive brood size manipulation, as a result of a low number of recruits, poor future reproduction of parents, or both. We analysed environmental influences on costs and optimization of reproduction on 6 years of natural and experimentally manipulated broods in a Central European population of the collared flycatcher. Based on dramatic differences in caterpillar availability, we classified breeding seasons as average and rich food years. The categorization was substantiated by the majority of present and future fitness components of adults and offspring. Neither observational nor experimental data supported the individual optimization hypothesis, in contrast to a Scandinavian population of the species. The quality of fledglings deteriorated, and the number of recruits did not increase with natural clutch size. Manipulation revealed significant costs of reproduction to female parents in terms of future reproductive potential. However, the influence of manipulation on recruitment was linear, with no significant polynomial effect. The number of recruits increased with manipulation in rich food years and tended to decrease in average years, so control broods did not recruit more young than manipulated broods in any of the year types. This indicates that females did not optimize their clutch size, and that they generally laid fewer eggs than optimal in rich food years. Mean yearly clutch size did not follow food availability, which suggests that females cannot predict food supply of the brood-rearing period at the beginning of the season. This lack of information on future food conditions seems to prevent them from accurately estimating their optimal clutch size for each season. Our results suggest that individual optimization may not be a general pattern even within a species, and alternative mechanisms are needed to explain clutch size variation.

Female Terrestrial Isopods, Porcellio laevis Latreille (Isopoda: Oniscidea) Reduce Brooding Duration and Fecundity in Response to Physical Stress

Female Porcellio laevis (Isopoda: Oniscidea) brood eggs and young in ventral marsupial pouches, a reproductive strategy with pronounced physical and presumed fitness costs. This study examines the effect of physical stress on reproductive behavior. To induce excessive physical stress, gravid female P. laevis were subjected to five minutes of continuous locomotion daily throughout the brooding period. Stressed females exhibited significantly shorter brooding periods than controls. Although stressed and control groups did not differ in average body size, there was a strong trend of reduced fecundity in stressed females. These results indicate that female isopods modify critical elements of reproductive investment under conditions of physical stress.

Costs of parental care on hunting behaviour of Helobdella papillornata (Euhirudinea: Glossiphoniidae)

Helobdella papillornata, an Australian freshwater leech, feeds primarily on snails and has a high level of parental care involving brooding eggs and young, with direct feeding of young. Parental costs and offspring benefits from these behaviours are poorly understood. A potential cost of parental care may be a change in the time taken to hunt prey. To test this hypothesis, the hunting behaviour of adults without progeny, parents with eggs, and parents with young were compared. We found that parents brooding eggs had a significantly (P = 0.029) longer lag time to begin hunting than parents brooding young, and spent significantly (P = 0.018) less time actively hunting than non-brooding adults. These costs, which may represent lost potential for the parent’s future reproductive success, should be outweighed by the fitness benefits of improved growth and survival of offspring, if parental care is favoured by selection. The hunting costs of care in Helobdella and other benthic, dorsoventrally flattened leeches in the family Glossiphoniidae may be smaller than the costs of brood tending that would be imposed on other freshwater leeches, and this difference may help explain the restriction of care to a single clade of the Euhirudinea.

Ecological Relationship Between Body Size and Fecundity in the Slipper Shell, Crepidula onyx Sowerby (Gastropoda: Calyptraeidae) in Korean Waters

The aim of the present study was to investigate the ecological relationship between female body size (=shell length) and fecundity in a Korean population of protandric hermaphrodite, Crepidula onyx Sowerby, using 6 reproductive variables (the number of capsules per brood, capsule size, the number of embryos per capsule, total number of embryos per brood, egg size, and larval size). The investigation was based on 32 females, 107 egg capsules, 263 eggs, and 250 veliger larvae sampled in January 2000, from Yangpo, the southeastern coast of Korea. All foregoing reproductive variables, except larval size, were significantly correlated with the female body size (p<0.001<TEX>$\~0.01$</TEX>). There was a significant increase both in the number of capsules per brood and the number of embryos per capsule with female body size (p<0.001). Consequently, the fecundity of the female C. onyx increased with female body size to over 14.65 mm (the minimum size of egg brooding in the present study). This investigation, therefore, provides additional evidence that female fecundity of protandric hermaphrodites is positively correlated with female body size.

The physiology of induced molting

The initiation of seasonal feather molting in wild avian species frequently coincides with incubation of eggs and brooding of offspring. A period of natural inappetence or anorexia usually accompanies this molt. This is particularly true of the jungle fowl, the wild ancestor of the domestic chicken. Brooding of eggs by the jungle fowl is accompanied by spontaneous anorexia, with little food or water consumed throughout the period of egg incubation. During this time, the reproductive tract regresses, and feather molting is initiated. Selective breeding for a high rate of egg production has blunted the response of the commercial laying hen to exogenous environmental cues and reduced or eliminated the endogenous biological cues that coordinate initiation of seasonal molting. However, commercial layers retain in their physiological repertoire the ability to tolerate prolonged fasting and to undergo a spontaneous regression of the reproductive tract and feather molting. Induction of a coordinated molt, by manipulation of environmental and nutritional cues, or endocrine manipulation, can be used in domestic hens to regress and regenerate the reproductive tract. This improves subsequent egg production and eggshell quality. This process also induces temporary recrudescence of lymphoid tissues and may alter immune function in hens. The process of molting, and the subsequent recovery from the molt, may be viewed as a complex physiological constellation, induced by environmental and nutritional cues, involving endocrine systems, reproductive tissue structure and function, lymphoid structure, and immune function.

Hatching asynchrony, nestling competition, and the cost of interspecific brood parasitism

All parental hosts of heterospecific brood parasites must pay the cost of rearing non-kin. Previous research on nest parasitism by brown-headed cowbirds (Molothrus ater) concluded that competitive superiority of the typically more intensively begging and larger cowbird chick leads to preferential feeding by foster parents and causes a reduction in the hosts' own brood. The larger size of cowbird nestlings can be the result of at least two causes: (1) cowbirds preferentially parasitize species with smaller nestlings and lower growth rates; and/or (2) cowbirds hatch earlier than hosts. I estimated the cost of cowbird parasitism for each of 29 species by calculating the difference between hosts' published brood sizes in nonparasitized and parasitized nests and using clutch size to standardize values. In this analysis, greater incubation length and lower adult mass, surrogate measures of the hatching asynchrony and size difference between parasite and hosts, were both related to greater costs of cowbird parasitism without bias owing to phylogeny. To establish causality, I manipulated clutch contents of eastern phoebes (Sayornis phoebe) and examined whether earlier hatching by a single cowbird or phoebe egg reduces the size of the rest of the original host brood. As predicted, greater hatching asynchrony increased the proportion of the original phoebe brood that was lost. This measure of the cost of parasitism was partially owing to increased hatching failure of the original eggs in asynchronous broods but was not at all related to the size differences of older and younger conspecific nestmates. However, proportional brood loss owing to an earlier hatching conspecific was consistently smaller than brood loss owing to asynchronous cowbirds in both naturally and experimentally parasitized phoebe nests. These results imply that although hatching asynchrony is an important cause of the reduction of host broods in parasitized clutches, competitive features of cowbird nestlings remain necessary to explain the full extent of hosts' reproductive costs caused by interspecific brood parasitism. Copyright 2003.

DUNGENESS CRAB, CANCER MAGISTER, DO NOT EXTRUDE EGGS ANNUALLY IN SOUTHEASTERN ALASKA: ANIN SITUSTUDY

The reproductive biology of female Dungeness crabs was studied with crab-pot and dive-transect sampling in five bays within or near Glacier Bay National Park and Preserve, southeastern Alaska, in April and September yearly from 1992 to 1998. A large percentage of nonovigerous, mature females was found in April, a time when females were expected to be brooding eggs that hatch in May and June. Our study examined differences between ovigerous and nonovigerous females collected in April and September samples to corroborate our previous laboratory study in which we found nonannual egg extrusion among Dungeness crabs. Seasonal differences in the catches of ovigerous and nonovigerous females, crab sizes, shell condition, and appendage injury were examined. Additionally, all crabs collected from two bays were tagged beginning in the fall of 1995; tagging was conducted twice annually. Our pot and dive data indicate that females, particularly larger ones, do not extrude eggs annually. Larger females have lower molting probabilities, which limits mating potential and increases reliance on stored sperm. The tagging study confirmed that at least some females do not extrude eggs in one year and then extrude eggs at a later time without molting, thus skipping at least one reproductive season. A reproductive cycle of Dungeness crabs in Alaska is introduced which includes earlier egg extrusion by larger females and nonannual egg extrusion.

Estimating Reproductive Effort in Small Aquatic Invertebrates from Lipid Dynamics

ABSTRACT Invertebrates that brood eggs or offer parental care to developing embryos incur a cost of reproduction in addition to that associated with the production of eggs. This additional cost is difficult to quantify but it is important in shaping the reproductive strategy of organisms and for evaluating their life history trade-offs. I used lipid analyses to determine the energy expended by female amphipods during the incubation of eggs. Lipid levels in female Gammarus lacustris during incubation of eggs dropped from 18.2% after egg deposition into the brood pouch to 8.4% when young were released. This decrease equalled 13.0 J and was similar to the 14.6 J in lipid energy in the eggs.

Changes in plasma levels of gonadal steroids and putative gonadotropin in association with spawning and brooding behaviour of male demoiselles

Nesting male demoiselles Chromis dispilus were captured and blood sampled under water by divers, and plasma levels of reproductive hormones correlated with behavioural status at the time of capture. Plasma gonadotropin‐II (dGtH‐II) was measured using a heterologous assay based on carp GtH‐II standards and an antibody to the β‐subunit of cGtH‐II. Plasma samples diluted parallel to standards in the assay, and there was a significant transient increase in dGtH‐II in response to treatment with gonadotropin releasing hormone analogue (GnRHa). Male demoiselles had elevated plasma levels of dGtH‐II during periods of reproductive display, but low levels of dGtH‐II during periods of brooding, irrespective of egg stage. Plasma testosterone levels followed a similar pattern whereas plasma 11‐ketotestosterone and 17,20β‐dihydroxy‐4‐pregnen‐3‐one levels tended to remain elevated during the early phases of egg brooding. The results are consistent with earlier studies showing that reproductive hormone levels in demoiselles are behaviourally mediated, and support the view that behavioural alterations of reproductive endocrine status in fishes are mediated through the action of GnRH.

The ecology and feeding biology of two Polydora species (Polychaeta: Spionidae) found to ingest the embryos of host hermit crabs (Anomura: Decapoda) from the Philippines

AbstractThe ecology and feeding biology of two shell‐burrowing polydorids associated with hermit crabs from the Philippines were investigated. Polydora umangivora and P. robi were found in shells of 15 and 28 gastropod species, respectively, occupied by nine hermit crab species. Polydora umangivora constructs U‐shaped burrows in the outer shell while P. robi constructs burrows in the apex of the shell, extending to an opening along the columella of the upper body whorls. Polydora umangivora and P. robi preyed upon the embryos of three and seven species, respectively, of diogenid hermit crabs collected in the field. In laboratory feeding trials, P. robi ingested up to 230 developing eggs and 70 embryos of Calcinus gaimardii over a 6‐h period. The impact of embryo predation is more apparent in hermit crab species that produce small broods of eggs (Paguristes runyanae) than in species that produce large broods of eggs (Calcinus gaimardii). Polydora robi transports the embryos to the mouth by a combination of muscular and ciliary action of the palps; ingestion follows breakage of the attachment stalk between embryo and pleopod seta. Invertebrates known and suspected to feed on host hermit crab eggs are reviewed and the evolution of polydorid/hermit crab symbioses is discussed.

Flexibility in Reproductive Styles of Male St. Peter's Tilapia, Sarotherodon galilaeus (Cichlidae)

This study examins the flexibility of the reproductive styles in St. Peter's tilapia, Sarotherodon galilaeus (Cichlidae). Three years of monitoring and filming 111 reproduction cycles involving 15 individually marked males, revealed their behavioural repertoire to contain 12 dominant groups of tactics (marked A to L), revolving around three parameters: territoriality (T) or non-territoriality (NT) during spawning; brooding-participating (Br) or non participating (NBr) in brooding eggs; and pairing (P) or not forming (NP) pair bond with the selected female. The males demonstrate an ability to select alternative reproductive styles (ARS) that presented various combinations of the three major parameters. The most dominant group comprised T (territorial) males, which tended not to brood eggs and to desert the female after mating. However, over various reproductive cycles the same males also altered their behaviour from one tactic to another. Territoriality was the most conservative tactic, while brooding or not brooding was the most frequently changed tactic. Some types of males remained with their selected mate for one spawning only, whereas others stayed for up to five cycles, showing a high tendency toward monogamy. In some instances the presence of additional females influenced the decision-making of the male, decreasing his fidelity to his mate. The rich variety of reproductive tactics in S. galilaeus males and their ability to change from one tactic to another, characterizes the high flexibility and adaptability of this species. These qualities could be used to describe ecobehavioural morphs, similar to descriptions of ecomorphological or ecophysiological phenotypes.

LIFE HISTORY AND REPRODUCTION OF SYNCHELIDIUM LENOROSTRALUM (AMPHIPODA, OEDICEROTIDAE) IN A TEMPERATE SANDY SHORE, SOUTHERN KOREA

Abstract The life history and population structure of the amphipod Synchelidium lenorostralum were studied monthly for one year in the sandy shore at Dolsando, southern Korea. The life-history pattern was annual and iteroparous, with two dominant recruitments in fall (October to December) and spring (March to May). The sex ratio was female-biased, especially during breeding periods. The maximum size of females was 10.8 mm and 1.4 times larger than that of males. The mean body length of adults and brood size were greater in the spring breeding period than in the fall. There was a positive relationship between the brood size and body length of ovigerous females. The mean egg volume of stage I was more than 0.04 mm3 in December and March, but in other months it was less than 0.03 mm3. Egg volume was positively related to body length of ovigerous females and increased significantly at the phase between stage I and II. However, no significant relationship between egg volume and brood size was found. At any giv...

Food Threshold for Diapause in Daphnia under the Threat of Fish Predation

The chances of prey to survive and leave viable offspring may be determined by many environmental constraints, of which food conditions may be of key importance. When food is not limited, the high reproductive effort of a well-fed prey individual dis- playing various defensive responses may assure successful reproduction, whereas low food supplies may prevent it by limiting energy gains and expenditures on defense and procre- ation. Under low chances for survival of active forms in a local environment, production of diapausing forms of enhanced resistance to unfavorable conditions or dispersion to more favorable places may assure persistence. The laboratory batch-cultured experiments detailed here sought to test whether food concentration may influence probability of producing resting eggs by Daphnia when under chemically simulated predation pressure. In fish-free conditions, no production of resting eggs was observed with either the tested low (0.4 mg C/L) or high (1.6 mg C/L) food concentrations, whereas in fish treatments, resting eggs were produced by various proportions of females according to food concentration. With the limited food (0.4 mg C/ L) there was production of ephippial (dormant) eggs in the early broods of almost all females in the fish treatment. Where food concentrations were higher, proportions of ephippial females were progressively lower, with females postponing the formation of resting eggs until later broods. At the highest food concentration (1.6 mg C/L), only about 17% of females produced ephippia when exposed to cues. These results are considered to indicate an adaptive response of prey individuals to a simulated danger of predation in various food conditions, determining relative gains of producing active vs. dormant off- spring. It seems that D. magna may assess their chances of survival and successful reproduction in accordance with the anticipated danger of predation and food conditions, and enter diapause when the expected gains from diapause exceed those of active life. A graphical model explaining observed production of active vs. dormant offspring by D. magna under predation pressure at various food concentration is proposed.

FOOD THRESHOLD FOR DIAPAUSE INDAPHNIAUNDER THE THREAT OF FISH PREDATION

The chances of prey to survive and leave viable offspring may be determined by many environmental constraints, of which food conditions may be of key importance. When food is not limited, the high reproductive effort of a well-fed prey individual displaying various defensive responses may assure successful reproduction, whereas low food supplies may prevent it by limiting energy gains and expenditures on defense and procreation. Under low chances for survival of active forms in a local environment, production of diapausing forms of enhanced resistance to unfavorable conditions or dispersion to more favorable places may assure persistence. The laboratory batch-cultured experiments detailed here sought to test whether food concentration may influence probability of producing resting eggs by Daphnia when under chemically simulated fish predation pressure. In “fish-free” conditions, no production of resting eggs was observed with either the tested low (0.4 mg C/L) or high (1.6 mg C/L) food concentrations, whereas in “fish” treatments, resting eggs were produced by various proportions of females according to food concentration. With the limited food (0.4 mg C/L) there was production of ephippial (dormant) eggs in the early broods of almost all females in the “fish” treatment. Where food concentrations were higher, proportions of ephippial females were progressively lower, with females postponing the formation of resting eggs until later broods. At the highest food concentration (1.6 mg C/L), only about 17% of females produced ephippia when exposed to fish cues. These results are considered to indicate an adaptive response of prey individuals to a simulated danger of predation in various food conditions, determining relative gains of producing active vs. dormant offspring. It seems that D. magna may “assess” their chances of survival and successful reproduction in accordance with the anticipated danger of predation and food conditions, and enter diapause when the expected gains from diapause exceed those of active life. A graphical model explaining observed production of active vs. dormant offspring by D. magna under predation pressure at various food concentration is proposed.

Reproductive cycle and fecundity of Chionoecetes japonicus (Brachyura: Majidae) off the coast of Central Honshu, Sea of Japan

SUMMARY: Chionoecetes japonicus is one of the most important commercially fished species in the Sea of Japan. In spite of its economic importance, only limited information on reproduction of this species was hitherto available. Although the reproductive cycle is one of the most important and basic aspects for management, two contrasting opinions have emerged so far: one suggesting a biennial reproductive cycle and the other suggesting a 4-year reproductive cycle. Females of C. japonicus were collected in baited crab pots set on the bottom at depths of 800–1000 m off Jhoetsu, Central Honshu, the Sea of Japan, on nine occasions from April 1993 to April 1994. Carapace width, brood developmental stage and ova size were estimated and analyzed quantitatively. A size frequency histogram showed that most females matured at a modal size of 68.1 mm carapace width, while a small number of crabs matured at modal sizes of either 58.6 or 77.0 mm. Almost all females were multiparous as all but one of the 300 females examined in March had new and/or old ejaculates in their spermathecae. Most multiparous females hatch their larvae and spawn in March and April. Quantitative analysis of ovaries and broods indicated that C. japonicus has a biennial reproductive cycle. The number of eggs in broods varied widely ranging from 0–60 800 eggs, and brood size was correlated with maternal size (P <0.01).

Nest, but Not Egg, Fidelity in a Territorial Salamander

Egg recognition and subsequent egg brooding are costly forms of parental investment in many species of vertebrates. Life history factors, such as coloniality or risk of brood parasitism, may constrain egg recognition in vertebrates. Female red‐backed salamanders (Plethodon cinereus) from my study site are territorial and do not share nest sites with other females. They are terrestrial and neither they nor their eggs are likely to be displaced by environmental factors such as flooding. I experimentally tested, in the laboratory, the hypothesis that female red‐backed salamanders can discriminate between their own eggs and the eggs of unfamiliar females. Each female was allowed to move about a test chamber containing two clutches of eggs, one clutch with which it was found in the forest and one that had been found with a distant female. Most females remained with one clutch of eggs, which they brooded during the entire observation period. However, they did not significantly prefer to brood their own eggs over the eggs of another female. In a corollary field experiment, I tested whether brooding females that were displaced 1 m from their nest sites would return to their territories and commence brooding behaviour within 3 d. All 10 displaced females returned to their own nest within this time period and were found brooding their eggs. Because female red‐backed salamanders at my study site do not tend to share nest sites with other females and because their eggs remain in stationary nests, selection may not have favoured egg recognition. However, the results suggest that female salamanders indirectly recognize their own eggs by actively recognizing their territorial nest sites.