Annual Fecundity Research Articles

Female age at maturity and fecundity in Atlantic Striped Bass

AbstractObjectiveFemale age at maturity and fecundity for the Atlantic stock of Striped Bass Morone saxatilis were estimated using histological methods and image analysis.MethodsOvaries were obtained from surveys encompassing the spring spawning season (March–July; n = 343), primarily from the Chesapeake Bay, and in the fall months (September–December; n = 85), primarily from the Atlantic coast. Histological examination of oocytes revealed some Striped Bass in intermediate stages of maturation during the spawning season. These individuals were identified as undergoing pubertal development, defined as the transition from the juvenile stage to first sexual maturity. Pubertal development was characterized by ovaries containing a population of enlarged, lipid‐filled oocytes but noticeably lacking vitellogenin‐derived yolk globules during the spawning season, and those ovaries were classified as immature. Toward the end of the spawning season, increasing proportions of Striped Bass with unspawned ovaries and oocytes undergoing total atresia were observed.ResultThe female age and length at 50% maturity in Atlantic Striped Bass based on spring samples were 5.5 years and 609 mm total length, respectively. Fecundity was determined gravimetrically via image analysis of ovarian tissue samples from spawning capable individuals (n = 67). Potential annual fecundity was found to exhibit hyperallometric scaling with respect to body size. Specifically, the scaling exponent for the length–fecundity relationship was 3.24, which was greater than the scaling exponent of 3.05 for the length–body mass relationship. This indicates that large females possess a disproportionately greater reproductive capacity with respect to body mass than the equivalent biomass of smaller females.ConclusionCompared with previous studies spanning over a half‐century, age at 50% maturity and fecundity were found to be relatively invariant, although variation found between contemporary studies may represent methodological and interpretive differences. Reproductive‐related life history traits of female Atlantic Striped Bass are apparently robust to long‐term decadal changes in fishing intensity, stock size, habitat alterations, and environmental conditions.

Temporal constraints influence reproductive characteristics that are related to the pace‐of‐life continuum in geese

Among avian species, particularly those with altricial young, life‐history strategies are characterized by a ‘slow’ pace‐of‐life at lower latitudes, where relatively low annual investments in reproduction are traded‐off for increased survival. Evidence for this pattern in precocial species, however, is equivocal, and questions about ecological drivers of latitudinal variation in reproduction remain. To better understand spatial variation in pace‐of‐life and related reproductive traits across bird species and to test a hypothesis that might explain observed spatial patterns, we analysed breeding data from closely related Canada Geese Branta canadensis and Cackling Geese Branta hutchinsii, hereafter Canada‐type geese, comprising eight sub‐species from 16 sites across a broad gradient of latitude (32°N to 69°N) and season length. Unlike the pattern reported for many altricial species, Canada‐type geese did not show reduced annual fecundity at lower latitudes, and instead this reduced reproductive investment was at higher latitudes. For three of five reproductive traits, the relative influence of growing season length (GSL; an index of the time available to breed) was greater than that of latitude. A shorter GSL resulted in later nest initiations, shorter pre‐laying intervals and higher seasonal rates of clutch size decline. Our results suggest that these and other species of geese are able to circumvent nutritional and temporal constraints imposed by shorter GSL by storing and using nutrient reserves for egg laying and incubation. Relative flexibility in reproductive traits may permit Canada‐type geese to accommodate predicted increases in climatic variability, compared to species with more rigid reproductive strategies.

Implications of big, old, fat, fecund, female fish (BOFFFFs) for the reproductive potential of a demersal teleost stock

The ‘big old fat fecund female fish’ (BOFFFF) hypothesis suggests that larger, older female fish contribute disproportionately more to the reproductive potential of a stock than smaller, younger female fish. As fishing typically differentially removes larger, mature fish, this can negatively impact reproductive potential and impair the recovery of a depleted stock. In this study, the BOFFFF hypothesis was explored quantitatively for the endemic West Australian dhufish (Glaucosoma hebraicum) by estimating the relationships between total length (TL) of females and spawning season duration, spawning frequency and oocyte size. The impacts of these size effects on estimates of reproductive potential of the G. hebraicum stock were also explored using a per-recruit analysis. Larger (900 mm TL), older mature female G. hebraicum were shown to spawn for a longer duration (six versus two months) and on more occasions (155 versus 60 times) than smaller (350 mm TL), younger mature fish, and thus these larger females have higher annual fecundity. Larger, older mature G. hebraicum also spawn, on average, significantly larger oocytes with greater estimated energy content (474.6 μm diameter and 0.234 J versus 379.9 μm and 0.140 J). Due to these size effects, reproductive output of G. hebraicum scales hyperallometrically with fish body mass, rather than isometrically. Not accounting for these size effects in per-recruit analysis resulted in higher estimates of stock reproductive potential and thus stock status. Such overestimates, if used to inform management, have the potential to result in harvest rates being set too high which, in turn, could thus affect stock sustainability.

The reproductive biology and fecundity of female Atlantic Menhaden

AbstractObjectiveAtlantic Menhaden Brevoortia tyrannus support fisheries that yield the largest landings by volume on the U.S. East Coast and fulfill a critical ecological role as a forage species. The spawning reference point of the stock assessment model that is routinely applied to this species requires information on total annual fecundity. The goal of this study was to generate a contemporary, histology‐based evaluation of the reproductive biology and fecundity of female Atlantic Menhaden.MethodsFemale Atlantic Menhaden (n = 559) were collected between Cape Cod, Massachusetts, and Cape Hatteras, North Carolina, from 2013 to 2019. Ovarian tissues were prepared using standard histological techniques which, when coupled with oocyte size‐frequency and count data, were used to classify reproductive mode and estimate batch fecundity, spawning frequency, and maturity. Monthly gonosomatic indices were combined with published female reproductive information and spatiotemporal patterns in larval and juvenile abundance to designate spawning seasonality.ResultHistological preparations and oocyte size‐frequency patterns of female Atlantic Menhaden ovaries were consistent with indeterminate batch spawning. Batch fecundity increased with fork length, while spawning seasonality extended from September 15 to April 15 with a spawn every 7.5 ± 2.3 days. Female maturity probabilities transitioned from 0.2 to 0.8 over fork lengths of 214.8–226.5 mm (approximately ages 2.0–2.3 years). Estimated mean per capita female annual fecundity varied from 465,757 to 3,250,135 oocytes for fish ranging from 215.8 to 284.8 mm fork length (ages 2–6 years), which represented a 614–2267% (mean = 1656%) increase in annual female reproductive output relative to previous estimates.ConclusionFemale Atlantic Menhaden exhibit indeterminant batch spawning while spawning seasonality and mean per capita female annual fecundity were appreciably greater than previously reported. This new reproductive information illuminates the robust reproductive productivity of this species and will aid routinely conducted stock assessments.

Individual life histories: neither slow nor fast, just diverse.

The slow-fast continuum is a commonly used framework to describe variation in life-history strategies across species. Individual life histories have also been assumed to follow a similar pattern, especially in the pace-of-life syndrome literature. However, whether a slow-fast continuum commonly explains life-history variation among individuals within a population remains unclear. Here, we formally tested for the presence of a slow-fast continuum of life histories both within populations and across species using detailed long-term individual-based demographic data for 17 bird and mammal species with markedly different life histories. We estimated adult lifespan, age at first reproduction, annual breeding frequency, and annual fecundity, and identified the main axes of life-history variation using principal component analyses. Across species, we retrieved the slow-fast continuum as the main axis of life-history variation. However, within populations, the patterns of individual life-history variation did not align with a slow-fast continuum in any species. Thus, a continuum ranking individuals from slow to fast living is unlikely to shape individual differences in life histories within populations. Rather, individual life-history variation is likely idiosyncratic across species, potentially because of processes such as stochasticity, density dependence, and individual differences in resource acquisition that affect species differently and generate non-generalizable patterns across species.

Reproductive traits exhibited by the paedomorphic gobies exploited in the Majorcan transparent goby fishery (western Mediterranean) and their management implications

An important small-scale fishery in Majorca targets three similar goby species: Aphia minuta, Pseudaphia ferreri and Crystallogobius linearis. Histological examination of the gonads of these species sampled from landings during the fishing season revealed characteristic reproductive traits that could be defined as abbreviate iteroparity. The transparent goby (Aphia minuta) and Ferrer’s goby (Pseudaphia ferreri) showed batch abbreviate iteroparity as a reproductive strategy, whereas the crystal goby (Crystallogobius linearis) showed total abbreviate iteroparity. Despite their short lifespans, all of them have a spawning season whose duration is longer than the legal fishing season. Additionally, all of them maintain a standing stock of primary growth oocytes in their gonads, indicating more than one spawning season in their lifespan. These reproductive features partially offset their special sensitivity to potential overexploitation and environmental changes but also suggest that the fishery needs special management to avoid breaking the balance between sustainability and fishing effort. The results of size at maturity and potential annual fecundity in the three species of the fishery are also reported and discussed.

Prospecting movements link phenotypic traits to female annual potential fitness in a nocturnal predator

Recent biologging technology reveals hidden life and breeding strategies of nocturnal animals. Combining animal movement patterns with individual characteristics and landscape features can uncover meaningful behaviours that directly influence fitness. Consequently, defining the proximate mechanisms and adaptive value of the identified behaviours is of paramount importance. Breeding female barn owls (Tyto alba), a colour-polymorphic species, recurrently visit other nest boxes at night. We described and quantified this behaviour for the first time, linking it with possible drivers, and individual fitness. We GPS-equipped 178 female barn owls and 122 male partners from 2016 to 2020 in western Switzerland during the chick rearing phase. We observed that 111 (65%) of the tracked breeding females were (re)visiting nest boxes while still carrying out their first brood. We modelled their prospecting parameters as a function of brood-, individual- and partner-related variables and found that female feather eumelanism predicted the emergence of prospecting behaviour (less melanic females are usually prospecting). More importantly we found that increasing male parental investment (e.g., feeding rate) increased female prospecting efforts. Ultimately, females would (re)visit a nest more often if they had used it in the past and were more likely to lay a second clutch afterwards, consequently having higher annual fecundity than non-prospecting females. Despite these apparent immediate benefits, they did not fledge more chicks. Through biologging and long-term field monitoring, we highlight how phenotypic traits (melanism and parental investment) can be related to movement patterns and the annual potential reproductive output (fecundity) of female barn owls.

Fecundity strategy of the highly exploited limpet Patella ordinaria from an oceanic archipelago

Limpet harvesting dates to the 15th century in Madeira archipelago (NE Atlantic Ocean). This activity is size-selective, removing older and larger individuals with greater commercial value. It can lead to a lower reproductive output as individual fecundity is size-dependent. The decrease of limpet populations has led to the implementation of a series of management measures including a closed season during the reproductive season (November–March). So far, sizes and the reproductive parameters, size and age at first maturity, have been previously used to determine the exploitation status of Patella ordinaria in Madeira archipelago, with no study performed on the reproductive strategy of this limpet. This is pivotal to comprehend the population dynamics of any species, being fecundity one of the reproduction parameters that should be analysed. This work aims to provide for the first time data on the fecundity of P. ordinaria. An average of 17 females per month were randomly collected over the spawning 2021/2022 season from the subtidal rocky shores of the Madeira archipelago. Four criteria were analysed over the spawning season: (i) the presence of a hiatus between pre- and vitellogenic oocytes; (ii) the number and (iii) mean size of advanced vitellogenic oocytes; and (iv) the incidence of atresia. A hiatus between pre- and vitellogenic oocytes across the spawning season was observed. An increasing trend in the number of vitellogenic oocytes was observed over the spawning season. The size of vitellogenic oocytes showed significant differences among months and the relative intensity of atresia varied from 7.86 to 20.79%. The information on the fecundity strategy leads to a better understanding of the reproductive capacity of this species. It also identifies the best approach for future estimations of relative annual fecundity estimations, with direct implications on the sustainable exploitation of this commercial species.

Improved status of the conservation reliant Oahu Elepaio through effective management and natural adaptation

AbstractThe Oahu Elepaio (Chasiempis ibidis) is an endangered forest bird endemic to the Hawaiian island of Oahu. The two most serious threats to the Oahu Elepaio are nest predation by nonnative black rats (Rattus rattus) and avian pox (Avipoxvirus spp.), a disease carried by nonnative mosquitoes. The Oahu Elepaio is conservation reliant because its continued existence depends on rat control. We used 27 years of data from 1995 to 2021 on pox prevalence, nest success, and fecundity with versus without rat control to reexamine the severity of these threats. Prevalence of avian pox declined over time. From 1995 to 2004, pox prevalence averaged 21% ± 4% per year and was positively related to annual rainfall. From 2005 to 2021, pox prevalence was only 2% ± 0.1% and despite several wet years there was no relationship with rainfall. The Oahu Elepaio appears to have evolved resistance to the pox variant currently in Hawaii. Elepaio nest success was higher with rat control (58% ± 1%) than without rat control (42% ± 6%). Nest success did not differ significantly between native tree species (52% ± 6%) and nonnative tree species (58% ± 6%) or between fruiting tree species (58% ± 1%) and nonfruiting species (61% ± 6%). Elepaio annual fecundity was higher with rat control (0.78 ± 0.02) than without rat control (0.48 ± 0.04) and varied among sites and years. The two primary threats to the species have been ameliorated through a combination of effective management and natural adaptation. The species' status should continue to improve if management is maintained, and someday, if patterns of natural adaptation continue, it could break free from conservation reliance.

Brood parasitism of Hooded Warblers by Brown-headed Cowbirds: Severe impact on individual nests but modest consequences for seasonal fecundity and conservation

Abstract Brood parasitism by Brown-headed Cowbirds (Molothrus ater) often has pronounced negative effects on host nests. However, the extent to which parasitism reduces annual reproduction and presents conservation challenges for host species is unclear. We address this issue with data from a color-banded population of Hooded Warblers (Setophaga citrina) in Pennsylvania, where Hooded Warblers have increased dramatically despite frequent nest parasitism. Our analysis is based on both an extensive dataset (8 years, 847 nests) on the per-nest impacts of cowbird parasitism and female-based stochastic simulations that accurately reflect the reproductive biology and parasitism rate (30%) of our study population. Cowbird parasitism has multiple negative consequences for Hooded Warbler nests, including (1) reduced host clutch size; (2) increased nest abandonment; (3) increased risk of complete failure due to predation; and (4) in surviving nests increased egg loss, hatching failure, and nestling mortality. We estimate that parasitism reduces success of Hooded Warbler nests 68%, from 1.29 to 0.41 fledglings per nest. For females and populations, however, the consequences of nest parasitism are considerably less extreme; female annual fecundity decreases 25% for each nesting attempt parasitized, and population-level fecundity drops 5.6% for each 10% increase in the frequency of parasitism. These more modest impacts are attributable to (1) steep declines in rates of cowbird parasitism as the nesting season progresses, (2) rapid renesting following abandonment or failure of parasitized nests, and (3) regular double brooding, with second broods initiated in late June and July when the incidence of cowbird parasitism is low. Our results help resolve the paradox of how cowbird parasitism can have both severe consequences for individual host nests but more modest and sustainable conservation impacts on the seasonal fecundity of females and populations. They further underscore the importance of determining population-level effects of brood parasites before investing in costly management efforts.

Comparing Life Histories of the Shortest-Lived Turtle Known (Chicken Turtles, Deirochelys reticularia) with Long-Lived Blanding's Turtles (Emydoidea blandingii)

Evolutionary theories predict major differences in life-history trait values of long- and short-lived organisms. Such comparisons have not been possible for chelonians because no short-lived turtle was known until research revealed that chicken turtles (Deirochelys reticularia; DR) have a maximum longevity of 21 yrs. Life-history trait values of DR females are 1) age at maturity of females = 5–6 yrs; 2) clutches per season = 1.6; 3) annual fecundity = 6–8 female eggs per female; 4) average juvenile survivorship from age 1 to maturity = 0.60; and 5) low average annual adult survivorship = 0.66. We compared DR with the very long-lived Blanding's turtles (Emydoidea blandingii; EB) in Michigan. Over 14 yrs with no mortality (the minimum age at maturity of EB), the maximum potential fecundity produced by a single female embryo and her mature female offspring was 5 female eggs for EB and 1040 eggs for DR. Comparisons of life table output for approximately stable populations of DR and EB resulted in cohort generation times of 7 and 37 yrs, respectively. The life-history prediction that short-lived organisms should produce smaller offspring was not supported. Average wet mass of eggs is 10 g (8.4–11.3 g) for DR and 12 g (10–14 g) for EB; and average wet mass of hatchlings is 7.3 g (6–9 g) for DR and 9.3 g (6–13 g) for EB. Both differences are smaller than expected based on the difference in longevity. Short-lived female DR have an unusual tactic of investing in high fecundity and making substantial body size-specific investment in large eggs, which may reflect why juvenile survivorship had greater influence on population change rates than did adult survivorship. In contrast, adult survivorship had the greatest influence on population change rates of EB. Comparison of cohorts of 1000 female DR and EB hatchlings highlights the differences in life histories of short- and long-lived turtles: all DR would be dead by the time the last female EB had reached maturity at 21 yrs of age.

Projected Climate and Hydroregime Variability Constrain Ephemeral Wetland-Dependent Amphibian Populations in Simulations of Southern Toads.

Amphibian populations are threatened globally by stressors, including diminishing availability of suitable wetland breeding sites, altered hydroregimes driven by changing weather patterns, and exposure to contaminants. Ecological risk assessment should encompass spatial and temporal scales that capture influential ecological processes and demographic responses. Following the PopGUIDE framework of population model development for risk assessment, we used matrix population models, in conjunction with existing hydroregime predictions, under a climate change scenario to evaluate the effects of environmental stochasticity and aquatic pesticide exposure on amphibians that are dependent on ephemeral wetlands. Using southern toads (Anaxyrus terrestris) as an example, we simulated population dynamics with breeding success dependent on hydroregime suitability. Years were defined as optimal, marginal, or insufficient for successful toad recruitment, based on the duration of their potential breeding season and rate of larval development to metamorphosis. We simulated both probabilistic and chronologically specific population projections, including variable annual fecundity, based on hydroregime suitability and reduced larval survival from carbaryl exposure. In our simulations, populations were more negatively impacted by prolonged drought, and consequently multiple sequential years of reproductive failure, than by aquatic pesticide exposure. These results highlight the necessity of reliable climate projections to accurately represent the effects of altered hydroregimes on amphibian populations. Risk assessment approaches could be improved with flexible modifications that allow inclusion of various extrinsic stressors and identification of demographic and ecological vulnerabilities when precise data are lacking.

Exceptional parallelisms characterize the evolutionary transition to live birth in phrynosomatid lizards

Viviparity, an innovation enhancing maternal control over developing embryos, has evolved >150 times in vertebrates, and has been proposed as an adaptation to inhabit cold habitats. Yet, the behavioral, physiological, morphological, and life history features associated with live-bearing remain unclear. Here, we capitalize on repeated origins of viviparity in phrynosomatid lizards to tease apart the phenotypic patterns associated with this innovation. Using data from 125 species and phylogenetic approaches, we find that viviparous phrynosomatids repeatedly evolved a more cool-adjusted thermal physiology than their oviparous relatives. Through precise thermoregulatory behavior viviparous phrynosomatids are cool-adjusted even in warm environments, and oviparous phrynosomatids warm-adjusted even in cool environments. Convergent behavioral shifts in viviparous species reduce energetic demand during activity, which may help offset the costs of protracted gestation. Whereas dam and offspring body size are similar among both parity modes, annual fecundity repeatedly decreases in viviparous lineages. Thus, viviparity is associated with a lower energetic allocation into production. Together, our results indicate that oviparity and viviparity are on opposing ends of the fast-slow life history continuum in both warm and cool environments. In this sense, the ‘cold climate hypothesis’ fits into a broader range of energetic/life history trade-offs that influence transitions to viviparity.

Sexual size monomorphism may evolve in lizards with a body size maximizing reproductive performance for both sexes.

We used Takydromus septentrionalis, a sexually size-monomorphic lacertid lizard, as a model system to test the hypothesis that sexual size monomorphism may evolve in lizards where reproductive performance is maximized at a similar body size for both sexes. We allowed lizards housed in laboratory enclosures to lay as many clutches (for females) as they could or to mate as many times (for males) as they could in a breeding season. Size-assortative mating was weak but evident in T. septentrionalis, as revealed by the fact that male and female snout-vent lengths (SVLs) in mating pairs were significantly and positively correlated. Mating frequency (indicative of male reproductive performance) varied from 1 to 8 per breeding season, generally increasing as SVL increased in adult males smaller than 67.4 mm SVL. Clutch frequency varied from 1 to 7 per breeding season, with female reproductive performance (determined by clutch frequency, annual fecundity, and annual reproductive output) maximized in females with a SVL of 68.0 mm. Accordingly to our hypothesis, the reproductive performance was maximized in the intermediate sized rather than the largest individuals in both sexes, and the body size maximizing reproductive performance was similar for both sexes. Future work could usefully investigate other lineages of lizards with sexually monomorphic species in a phylogenetic context to corroborate the hypothesis of this study.

Age-specific, population-level pedigree of wild black bears provides insights into reproduction, paternity, and maternal effects on offspring apparent survival.

Wildlife pedigrees provide insights into ecological and evolutionary processes. DNA obtained from noninvasively collected hair is often used to determine individual identities for pedigrees and other genetic analyses. However, detection rates associated with some noninvasive DNA studies can be relatively low, and genetic data do not provide information on individual birth year. Supplementing hair DNA stations with video cameras should increase the individual detection rate, assuming accurate identification of individuals via video data. Video data can also provide birth year information for individuals captured as young of the year, which can enrich population‐level pedigrees. We placed video cameras at hair stations and combined genetic and video data to reconstruct an age‐specific, population‐level pedigree of wild black bears during 2010–2020. Combining individual birth year with mother–offspring relatedness, we also estimated litter size, interlitter interval, primiparity, and fecundity. We used the Cormack‐Jolly‐Seber model in Program Mark to evaluate the effect of maternal identity on offspring apparent survival. We compared model rankings of apparent survival and parameter estimates based on combined genetic and video data with those based on only genetic data. We observed 42 mother–offspring relationships. Of these, 21 (50%) would not have been detected had we used hair DNA alone. Moreover, video data allowed for the cub and yearling age classes to be determined. Mean annual fecundity was 0.42 (95% CI: 0.27, 0.56). Maternal identity influenced offspring apparent survival, where offspring of one mother experienced significantly lower apparent survival (0.39; SE = 0.15) than that of offspring of four other mothers (0.89–1.00; SE = 0.00–0.06). We video‐documented cub abandonment by the mother whose offspring experienced low apparent survival, indicating individual behaviors (e.g., maternal care) may scale up to affect population‐level parameters (e.g., cub survival). Our findings provide insights into evolutionary processes and are broadly relevant to wildlife ecology and conservation.

Drivers of the Australian native pet trade: The role of species traits, socioeconomic attributes and regulatory systems

Abstract The pet trade is a major driver of both biodiversity loss and the introduction of invasive alien species. Building a comprehensive understanding of the pet trade would improve prediction of conservation and biosecurity threats, with the aim to prevent further negative impacts. We used South Australia’s native wildlife permit reporting system as a data‐rich example of a vertebrate pet market, spanning 590 distinct taxa across 105 families of terrestrial vertebrates (mammals, reptiles, birds and amphibians). Using a piecewise structural equation modelling (SEM) approach, we tested the influence of 11 a priori variables relating to pets (e.g. species traits), pet owners (e.g. socioeconomic metrics) and regulatory systems (e.g. permit requirements) on the quantities of captive pet keeping, breeding, trading and escapes into the wild. Birds and reptiles with higher annual fecundity were more likely to be kept in captivity and birds with larger adult mass were more likely to be sold. Species with more stringent permit requirements were possessed and escaped, in lower abundances. Pet keeping was weakly correlated with regions of lower human population densities and higher unemployment rates, yet all socioeconomic variables were ultimately poor at explaining trade dynamics. More escapes occurred in regions that possessed larger quantities of pets, further emphasising the role of propagule pressure in the risk of pet escapes. Synthesis and applications. Species traits are a strong determinant of native pet trade dynamics, yet permit systems also play a key role in de‐incentivising undesirable trade practices. While our research highlighted the positive potential of trade regulatory systems, we recommend that consistent permit category criteria are established to reduce trade in threatened species as well as invasive alien species of high biosecurity risk. Implementation of such systems is broadly needed across a greater diversity of wildlife markets and jurisdictions.

Nesting attempts and annual fecundity in a population of the yellow-chinned spinetail (Certhiaxis cinnamomeus), with a review on Neotropical passerines

Nesting attempts and annual fecundity in a population of the yellow-chinned spinetail (Certhiaxis cinnamomeus), with a review on Neotropical passerines

Species Traits Drive Long-Term Population Trends of Common Breeding Birds in Northern Italy.

Simple SummaryWe assessed population trends for breeding birds in Lombardy (N Italy) from 1992 to 2019 and investigated the relationships between the observed trends and groups of species sharing similar characteristics (i.e., functional groups). We found a general positive or stable situation for 76% of the species. However, about 24% of the species declined, with worrying negative trends (greater than −50%) for two-thirds of them. Regarding species groups, we found that populations of migrants, of species with short incubation period, and of species with high annual fecundity declined. Similarly, populations of plant-eaters, of species feeding on invertebrates, and of farmland birds decreased. Only populations of woodland birds increased. In conclusion, our study provided a portrait of the status of common breeding birds in the region. Moreover, by analyzing the population response of the functional groups, we identified which of them experienced the most significant population changes, providing the foundations to implement studies aimed at quantifying the effects of specific divers responsible of the observed population changes in these groups.Long-term population trends are considerable sources of information to set wildlife conservation priorities and to evaluate the performance of management actions. In addition, trends observed in functional groups (e.g., trophic guilds) can provide the foundation to test specific hypotheses about the drivers of the observed population dynamics. The aims of this study were to assess population trends of breeding birds in Lombardy (N Italy) from 1992 to 2019 and to explore the relationships between trends and species sharing similar ecological and life history traits. Trends were quantified and tested for significance by weighted linear regression models and using yearly population indices (median and 95% confidence interval) predicted through generalized additive models. Results showed that 45% of the species increased, 24% decreased, and 31% showed non-significant trends. Life history traits analyses revealed a general decrease of migrants, of species with short incubation period and of species with high annual fecundity. Ecological traits analyses showed that plant-eaters and species feeding on invertebrates, farmland birds, and ground-nesters declined, while woodland birds increased. Further studies should focus on investigation of the relationship between long-term trends and species traits at large spatial scales, and on quantifying the effects of specific drivers across multiple functional groups.

Fecundity pattern and spawning dynamics of the common cuttlefish Sepia officinalis

ABSTRACT The fecundity pattern of common cuttlefish, Sepia officinalis, was assessed in Thermaikos Gulf, one of the species’ main fishing grounds in the eastern Mediterranean. Female samples, collected with coastal fishing gears during the population spawning season (January–July), were analysed using a combination of histology and whole mount analysis of ovarian tissue. The potential fecundity was shown to vary seasonally, showing the highest values at the beginning of spawning, gradually dropping thereafter. Previtellogenic oocytes (<0.5 mm) were the most prevalent group occurring throughout the spawning period in all maturity stages. Low or null levels of oocyte recruitment during the spawning period in combination with seasonal drop in fecundity and clutch-specific egg production suggest that the fecundity pattern of cuttlefish displays similarities with the so-called ‘determinate fecundity’ pattern of fishes. Spent females end up having small reserves of secondary growth oocytes (pre- and vitellogenic) that will never be spawned. Potential annual fecundity was thus estimated as the difference in total fecundity between pre-spawners and spent females and equalled 2569 oocytes/eggs. For a spawning period of four months, the ratio between potential fecundity and clutch size (100–200 eggs) indicated 13–25 different spawning events with a mean interval of 5–9 days.

Effects of patch-burn grazing and rotational grazing on grassland bird abundance, species richness, and diversity in native grassland pastures of the Midsouth USA

Declines in native warm season grasslands have been linked to grassland bird population decline due to habitat loss including conversion to non-native grasses. Rotational grazing (ROT) and patch-burn grazing (PBG) are two possible tools to restore native warm-season grasses (NWSG) on working-lands in the Mid-South USA and thus aid in the recovery of grassland bird populations. This project compares ROT, PBG, and before treatment implementation to assess their effects on grassland-associated bird species. At three research sites between KY and TN, 14–10 ha NWSG pastures were established and randomly assigned 7 pastures each to ROT and PBG treatment and monitored avian relative abundance during the breeding season from 2014 to 2017. Avian call count data and vegetation characteristics were collected in 2014 and treated as a before treatment year. Following 2014, ROT and PBG treatments were implemented across each respective research site. We used the open N-mixture model framework to estimate avian relative abundance related to year, treatments, research site, and landscape and within-field variables. Avian species richness and diversity were calculated for each treatment, research site, and year. Landscape variables, within-field variables, and research sites exerted more influence on relative abundance than ROT or PBG. Grassland-associated bird species relative abundance and species richness/diversity were affected by habitat disturbances (both ROT and PBG) but varied by species and site. Field sparrows [Spizella pusilla] had the highest increase in relative abundance (9.68 ± 1.24 birds/point count location or 1.77 ha) while northern cardinals [Cardinalis cardinalis] exhibited a significant decrease in relative abundance (3.44 ± 1.54 birds/point count location) following treatment implementation on specific research sites. Species diversity and richness did not differ between ROT and PBG treatments. However, a site and year difference were observed for both estimates. Using ROT and/or PBG to create habitat disturbances can alter within-field variables (i.e., vegetation height) which, taken into context with landscape variables, could impact grassland bird populations and diversity depending on grassland bird species habitat requirements. Our research provided the baseline information for ROT and PBG impacts on grassland birds in the east/southeastern USA. However, we believe future research should focus on breeding and annual fecundity to better understand how populations will change over time and how working lands conservation might aid this conservation effort without a reduction in livestock productivity.