Urban environments pose novel challenges for songbirds, and the degree of urbanization can influence nesting success. We used a multi-year (2013-2021) quasi-experimental design to understand the relationship between urbanization and various nesting parameters derived from 380 Black-crested Titmouse (Baeolophus atricristatus; hereinafter BCTI) nests in nest boxes installed across an urbanization gradient (i.e., rural, and low, moderate, and high levels of urbanization) in San Marcos, Texas, USA. The number of eggs, nestlings, and fledglings per nest were negatively influenced by clutch initiation date but not by level of urbanization or year. First clutch initiation date was correlated with level of urbanization, with nests in areas with any level of urbanization being initiated approximately 12 d earlier than rural nests. First clutch initiation dates for all nests were also affected by weather, with warmer mean daily high February temperatures prompting earlier nest initiation. Nest success was similar in rural areas and in areas with low or high urbanization, but was significantly lower in moderately urbanized areas. Nest success was also negatively correlated with clutch initiation date. Overall, our results indicate that BCTI are demonstrating behavioral plasticity to urban environments with earlier lay dates, but that increasing urbanization does not reliably predict changes in nest success. Thus, different degrees of urbanization potentially act as source-sink locations for BCTI populations. Received 8 January 2023. Accepted 12 December 2023.

At lower latitudes ungulate reproduction is often seasonal, but the duration of mating and parturition seasons can be long. To further understand the adaptive significance of synchrony in reproductive events, we examined two hypotheses to link over-winter body mass with lower synchrony of conceptions in a wild population of white-tailed deer ( Odocoileus virginianus (Zimmermann, 1780)) in central Texas. If females maintain over-winter body mass, then the window of time that conception occurs should be relaxed and longer relative to females where over-winter body mass declines. Across 9 years, we measured body mass in 1.5-year-old and older females in November ( n = 170) and in March (118). In March, we also measured forehead–rump lengths in offspring of gravid females and calculated conception dates. Over-winter body mass did not decline but was maintained, on average, across the years of study. Conception dates ranged over 50 days and 52% of conceptions occurred in a 2-week period centered on the median conception date. Relative to northern populations of deer, there was lower synchrony in conception dates. White-tailed deer across the geographic range appear to be flexible in over-winter body mass dynamics that affects duration of reproductive events such as conception.

Antlers are a costly trait that require skeletal reserves to grow to a large size. Thus, insight into variation in antler size requires understanding the connection between antler and body size, which can be summarized through ontogenetic and static scaling relationships. Both types of scaling relationships are also needed to examine the influence of factors besides body mass on antler growth at different ages and whether the effects of these factors diminish with age. Dietary and maternal effects might decline with age as individuals attempt to mitigate size deficits. We examined the potential effects of diet and maternal attributes of dam (mother) age at birth and litter size on body-antler mass relationships throughout ontogeny and at discrete ages. Data on age, maternal characteristics, body mass, and antler mass were gathered from captive, pen-raised White-tailed Deer (n = 168) that consumed either a low-energy (1.77 kcal/g) or standard-energy diet (2.65 kcal/g) from the time they were weaned until they perished by 5.5 years of age. Both types of scaling relationships were estimated with linear mixed-effects models to account for repeated measurements of males, dams, and sires. Diet affected ontogenetic scaling relationships. Males eating the low-energy diet had faster antler growth when young and lighter in body mass than when they were older and heavier-whereas males fed the standard-energy diet had a similar rate of antler growth across the range of body masses. A Bayesian Information Criterion model selection analysis indicated that diet and litter size (singleton, multiple births), but not dam age at birth influenced static scaling relationships. Static scalar coefficients up to 3.5 years of age were positively allometric (>1.0), but isometric (1.0) in 4.5- and 5.5-year-old males. Furthermore, diet and litter size influenced both intercepts and slopes in only the youngest males (1.5 years) indicating that dietary and maternal effects can diminish with age. Body-antler mass relationships are complex. Young males that are small because of maternal effects, for example, might still be able to mitigate smaller body and antler sizes at older ages.

Large grazing mammals should negatively affect forage biomass of their food supply, but documentation is lacking in free ranging populations. Furthermore, complications from factors such as weather patterns and spatial heterogeneity might obscure grazing effects on the food supply. We examined influences of Roosevelt elk ( Cervus canadensis roosevelti (Merriam, 1897)) abundance and precipitation on forage biomass at two spatial scales; meadows that contained most of the food supply, and sectors nested in meadows. Spatial heterogeneity in forage biomass might also decline with increasing elk abundance. Elk abundance was estimated from population counts and varied 3.9-fold across the 15 years of study in northwestern California, USA. Each January, early in the growing season, we estimated forage biomass in the 50-ha meadow complex used by the elk population. Measures of palatable forage cover and height were taken in 270 ¼ m 2 plots dispersed throughout sectors. These measurements were then related to dried forage biomass. At both spatial scales, elk abundance was inversely, and precipitation was positively related to forage biomass. At the sector scale, analysis of a linear mixed effect model indicated heterogeneity. In some sectors both predictors were related to forage biomass and in other sectors they were not. Heterogeneity was not from uneven elk grazing as elk grazed sectors in proportion to forage biomass. The varied elk abundance–forage biomass relationships across sectors indicated that spatial heterogeneity declined with increasing elk abundance. Detecting relationships between free ranging ungulate populations and biomass of their food supply is not straightforward.

Ecological processes driving female-skewed adult sex ratios (ASRs; males:females) in populations with polygynous mating systems have been addressed theoretically, but empirical support is scarce. The theoretical framework of the female substitution hypothesis (FSH) asserts that a female-skewed ASR at carrying capacity reflects an overall fitness benefit for females and for males competitive in acquiring access to reproductive females. The FSH predicts that as population abundance increases females should acquire forage more efficiently than males, thereby leading to passive displacement of males. The result is declining ASR associated with differential habitat use by both sexes as food resources are depleted by female scramble competition. We characterized the temporal variation in ASR in a Roosevelt elk population inhabiting the Redwood National and State Parks, California, across 24 years, and determined which of two possible ecological mechanisms was the driver of a declining ASR. The first mechanism explored was that increasing female abundance associated with declining forage in the study area led to the passive displacement of males into the study periphery over time. The second mechanism explored was that a declining ASR was precipitated by a lack of males within the study area and the study periphery. Systematic population surveys from a vehicle were done to estimate abundance and ASR as well as assess male abundance in the study periphery. Forage biomass was estimated in quarter-m(2) plots randomly placed in meadows inhabited by female elk. Our multiple regression analysis revealed an inverse relationship between abundance and ASR indicating density dependence. We found numerous males in the study periphery when females were abundant. Our least squares models indicated declining food resources across years when female abundance increased. Our results showed that the first, and not the second, ecological mechanism examined was responsible for a female-skewed ASR. Our findings provide empirical support for the theoretical framework of the FSH in a nonmigratory population protected from hunting.

The Department is committed to developing and maintaining an effective, positive and cooperative relationship with California federally recognized Tribes (Tribes) regarding elk management.The Department and Tribes share authority to regulate the take of elk, with Tribes having authority on tribal lands and the Department over the remainder of the state.In order to achieve the goals regarding California's elk populations, innovative management actions and collaboration will be required, and guidance from a statewide elk management plan (management plan) is necessary to help mediate competing and conflicting interests.This elk management plan is designed to address these goals and objectives and assure the conservation, protection, restoration, enhancement and reestablishment of California's elk populations and habitat.This is critical to providing cultural, scientific, educational, recreational, aesthetic and economic benefits for present and future generations of Californians.The management plan describes historical and current geographic range, habitat conditions and trends, and major factors affecting Roosevelt, Rocky Mountain and tule elk in California.It identifies, delimits and describes high priority areas for elk management, referred to as Elk Management Units (EMUs) and establishes broad conservation and management objectives.The 22 EMUs collectively comprise the current known distribution of elk in California with few exceptions.The EMU plans are living documents with objectives focused on priori-additional information is gathered and updated independent of the main plan and other individual EMUs.Consistent with other species management plans, EMU plans contain specific information for each high priority area, organized under the following

Herbivores use vigilance to reduce predation risk and interact socially, yet it imposes a foraging efficiency cost. As individuals spend more time with their head up being vigilant, time available to search for and ingest food decreases. We explored whether ungulates can strategically modify behaviours to compensate for vigilance costs via increased cropping rate when food searching time was near-zero and bite sizes were small. We compared the proportion of time individuals had their head up to their cropping rate (bites/observation length) in 271 observations of Roosevelt elk ( Cervus elaphus roosevelti ). Using a linear mixed-effect model, we estimated the head up–cropping rate relationship and found that elk cropping rate was constant across varying lengths of time spent with their head up, indicating no vigilance compensation occurred via increased cropping rate. We discuss settings when cropping rate compensation is expected and other behaviours that might mitigate vigilance costs.

Research objectives were to determine nodule-forming capacities and competition for nodule-formation of Frankia strains ArI3 and Ag45/Mut15, which were assessed 90 days after planting of host seedlings in containers within soil microcosms. Both strains were inoculated in a ‘4 × 4’ factorial design with all combinations (n = 16) of cell numbers of the two strains (0, 102, 103, or 104 cells g−1 of soil) determined by qPCR. In all cases, inoculation significantly increased plant height compared to non-inoculated controls. Root nodules were formed on all inoculated plants with strain Ag45/Mut15 alone forming few nodules, for all inoculum amounts whiles strain ArI3 alone formed about ten-times more nodules at the lowest inoculum amount than Ag45/Mut15, with notable increases in nodule numbers for each ten-fold increase in inoculum. Except for nodules formed after inoculation of strain Ag45/Mut15 alone, nodules in all combinations harbored strain ArI3 only. Both strains were detected in rhizosphere soils for all three inoculum amounts. In contrast to nodules and rhizosphere soil, however, strain ArI3 was not detected in any bulk soil samples after three months of incubation, while strain Ag45/Mut15 was detected with densities about ten-fold higher than the original inoculum. These analyses demonstrate that strain ArI3 is initially more infective and competitive for root nodule formation than strain Ag45/Mut15. Strain Ag45/Mut15, however, survived and increased in cell numbers in bulk soil after 90 days whereas strain ArI3 disappeared indicating a reversal of competitive advantage between these two strains in the soil matrix over time.

Prescribed fires often stimulate short-term productivity of grasslands that influences use by large, grazing herbivores. But studies examining burning effects on large herbivore population dynamics while simultaneously considering other environmental factors that might also influence population dynamics are lacking. We examined the influences of burned area, precipitation during the growing season, and possible distributional shifts from a nearby public hunt on maximum intrinsic rate of population growth (r(max)) and environmental carrying capacity (K). We examined the influences of these predictors in a Roosevelt elk (Cervus elaphus roosevelti) population studied across 43 years where abundances ranged from 4 to 322 animals and prescribed fires ranged from 14 to 891 ha of burned area in Redwood National and State Parks, California, USA. The highest count across surveys conducted in a year was our index of elk (females, juveniles, subadult males) abundance. We estimated Ricker type models in a hierarchical, state-space formulation that separated observer error from process variation. We found a slight influence from burned area on both r(max) and K but a stronger influence from precipitation during the growing season. The lack of a substantial effect from burned area on elk population parameters might be from a variety of factors such as spatial and temporal variation in intensity of prescribed fires and weak density dependence. Nonetheless, one positive benefit to elk population processes was that the patchwork of burning retarded encroachment of woody plants into forage habitat and, thus, maintained a constant area of forage habitat across 43 years. (C) 2021 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.

An inverse density-dependent relationship between abundance and adult sex ratio (ASR, males:female) occurs in some populations of polygynous mammals due to life history differences between the sexes. Male fecundity and survival is dictated by attempts to obtain as many copulations as possible, whereas female fecundity and survival is dictated by resource acquisition. Therefore, females usually acquire forage before males as a result of intetspecific scramble competition, particularly when forage becomes more limited at K carrying capacity. This leads to the passive displacement of males in a given area. The common belief is that most monogamous mammal populations exhibit balanced adult sex ratios. The coupling of sexually mature males and females in a population result in this pattern for this mating system. Present literature focuses on primary or secondary sex ratios in mammals or on ASR patterns within individual species. Our goal was to test if expected ASR patterns would be visible across numerous species in both mating systems. We hypothesized we would see an inverse relationship between abundance and ASR across polygynous populations, and no relationship between abundance and ASR across monogamous populations. We extracted time series population data from published literature for 43 populations of 15 different mammal species. Results from our analysis of a linear mixed-effects model were consistent with our hypothesis for polygynous populations, as we found a significant inverse relationship between abundance and ASR. However, our analysis also revealed a significant inverse relationship between abundance and ASR in monogamous populations that was not consistent with our hypothesis. Our findings provide quantitative support for a theoretical model explaining the evolutionary and ecological mechanisms driving a density-dependent relationship between abundance and ASR in polygynous mammals. An investigation into monogamous mammals is needed to assess why some species with this mating system display a density-dependent response in ASR as well.

Habitat use by the Eastern Black Rail (Laterallus jamaicensis jamaicensis) in coastal Texas, USA is poorly understood. To provide data for effective management of the subspecies in Texas, home range size was estimated and habitat use was examined. From February-May of 2017 and 2018, regular locations of 13 radio-transmitted Eastern Black Rails were obtained at San Bernard National Wildlife Refuge, Texas. The mean fixed kernel home range for birds with >= 24 relocations was 2.3 ha, with a mean core area of 0.43 ha. Average 95% MCP home range was 0.98 ha with a mean core area of 0.12 ha. During radio tracking, an Eastern Black Rail nest was found on 19 March 2018, the earliest on record for the state. Birds used the Salt and Brackish High Tidal Marsh, Salty Prairie, and Baccharis (Baccharis spp.) Shrubland, and avoided Salt and Brackish Low Tidal Marsh. Home ranges contained a gently sloping elevation gradient suggesting the importance of on-foot access to higher ground. Protection and restoration of Salty Prairie, and Salt and Brackish High Tidal Marsh is recommended for maintaining Eastern Black Rail populations in coastal Texas. Received 4 June 2020, accepted 15 July 2021.

Group-size variation has been examined within a framework of costs and benefits to ecological factors such as food limitations and risks from predators. Social interactions between males from male-male competition might also influence group size particularly in polygynous males. To explore the role of social and ecological factors on group size outside the mating season I examined the influence of abundance on male grouping patterns in a population of Roosevelt elk (Cervus elaphus roosevelti) in northwestern California, USA. Male grouping patterns were complex, males often group with other males, but they also can be transient members of female groups. Because male-male competition is pervasive even outside of the mating season, sizes of groups comprised of males only should be positive and linearly related to abundance of the male population or frequency associated. Whereas the number of males in female groups should be inversely related to female abundance or density associated. Males associating with females is more likely at low female abundance because females might still be reproductively active and per capita forage should be abundant. Across a 23-year study I examined whether male or female abundance was related to male only group sizes and the number of males in female groups. Size of male-only groups displayed a positive, linear relationship with male abundance and the number of males in female groups exhibited an inverse, linear relationship with female abundance. Uncovering forces influencing male grouping patterns required using the appropriate metric of abundance. Social factors likely influenced sizes of male-only groups and ecological factors probably influenced male prevalence in female groups.

Prescribed fire should increase plant and forage biomass for herbivores in meadows, but the response is likely to be influenced by environmental conditions.Across 15 years prescribed fires occurred every two to four years in September in Boyes meadow, Humboldt County, California.We measured the presence or absence of prescribed fires in September, climatic conditions one month later, Roosevelt elk (Cervus elaphus roosevelti) abundance, and the biomass of elk forage in January.From analysis of a linear mixed effects model we found that prescribed fires increased forage biomass the first January post-burn and even more so a year after the burn.Forage biomass two years post-burn decreased but was still more than three to four years post-burn.October precipitation had a positive effect on forage biomass but we detected no influence from low temperature in October or elk abundance.Given that prescribed fire increased elk forage biomass two years later, continuing to burn Boyes meadow on a three to four year rotation is suggested.

We studied the ecological health of springs experiencing varying levels of urban development to assess impacts to rare endemic salamanders (Eurycea spp.) of Central Texas. We evaluated measures of invertebrate species richness, water quality, and contaminant uptake by salamanders to determine how springs and their inhabitants were being affected by urban growth and changing land-use patterns. The number of environmental contaminants present and concentrations of contaminants increased in both water and salamander tissues with increasing age of the developments (i.e., years postconstruction) and increasing levels of impervious cover (e.g., roads) in urban watersheds compared with nondeveloped sites. We conclude that urbanization and associated increases in pollutant loading in watersheds can result in a loss of spring biodiversity and the accumulation of persistent and potentially toxic pollutants in salamanders. Although we detected generally low levels of pollutants, the altered water quality and invertebrate composition observed at springs, coupled with the changing hydrology and chronic contaminant exposure inherent in urban landscapes, is cause for concern, with potential implications for the long-term health, survival, and recovery of salamanders.

Conflicting evidence exists supporting linear and nonlinear density‐dependent population growth when species have slow life histories. The Ricker (linear) and θ‐logistic (nonlinear) models are commonly used to analyze survey data for these species, but no evaluation has examined whether these hypotheses can be differentiated with field data. We conducted a simulation exploring effects from shape of density dependence and variation in vital rates on the fit of these models. When vital rates had moderate to high variation, the models had similar fit. The θ‐logistic model differed from the Ricker model and was biologically realistic (θ > 1) when variation in vital rates was low and the growth response was nonlinear. Furthermore, the θ‐logistic model has issues with model convergence when using vague priors and when variation in vital rates as high. These results indicate that the Ricker model is appropriate for population survey data of species with slow life histories.

Size dimorphic ungulates often display ecological differences attributed to body size. We predicted that male elk should select foraging sites containing more abundant forage than sites selected by smaller-bodied female and juvenile elk. To test this prediction, we estimated forage biomass at bite stations grazed by juvenile, adult female, and adult male Roosevelt Elk (Cervus elaphus roosevelti). Moreover, we examined the potential confounding influences of number of bites taken and group size on forage biomass at bite stations. We measured forage biomass associated with focal observations of 310 grazing elk (55 juveniles, 145 females, 110 males) in 2 meadow complexes in Redwood National and State Parks, California, 2008–2011. Analyzing a linear mixed effects model, our fixed effects showed that forage biomass at bite stations grazed by males tended to be greater than that of bite stations grazed by juveniles and females. When we considered the additional uncertainty from random effects, there was considerable overlap in 95% confidence intervals of estimated forage biomass at bite stations grazed by juvenile, female, and male elk. Therefore, the positive correlation between age-sex classes and forage biomass was weak. There also was no influence from number of bites taken at bite stations or group size on forage biomass at bite stations. When forage was limited, body size had a weak influence at bite stations grazed by juvenile, adult female, and adult male Roosevelt Elk.

Flexibility in gut morphology has fitness consequences in herbivores. To accommodate dietary variation in energy concentration, rumen–reticulum absorptive capacity and organ mass might also covary. We hypothesized that low energy diets result in greater food intake but lower volatile fatty acid concentrations. The consequence would be heavy rumen–reticulum organs and low absorptive capacity. We measured rumen–reticulum organ mass and absorptive capacity in captive white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) from central Texas, USA. Deer consumed a pelleted ration, ad libitum, of 1.77 kcal/g (low) or 2.67 kcal/g (standard) digestible energy from the time animals were weaned. In December, 4.5- and 5.5-year-old deer were euthanized, the rumen–reticulum was extracted, thoroughly rinsed, wrung out, and weighed. Four 1 cm × 3 cm samples were extracted from four regions of the rumen and mucosal surface area was measured. Our surrogate of food intake and mastication intensity was first molar height. Molar height was lower in animals consuming the low energy diet. Analyses indicated sex-specific responses. Males eating the low energy diet had heavier rumen–reticulum organs, but females did not. Females consuming the low energy diet had a lower surface enlargement factor, but males did not. The processes driving variation in rumen–reticulum morphology from dietary variation require further examination.

Population and land management relies on understanding population regulation and growth, which may be impacted by variation in population growth parameters within and among populations. We explored the interactions between variation in carrying capacity (K), intrinsic population growth rate (r), and strength of density dependence (β) within and among elk (Cervus elaphus) herds in a small part of the geographic range of the species. We also estimated stochastic fluctuations in abundance around K for each herd. We fit linear Ricker growth models using Bayesian statistics to seven time series of elk population survey data. Our results indicate that K and β varied among herds, and that r and β varied temporally within herds. We also found that herds with smaller K had less stochastic fluctuation in abundances around K, but higher temporal variation in β within herds. Population regulation and the rate of return to the equilibrium abundance is often understood in terms of β, but ecological populations are dynamic systems, and temporal variation in population growth parameters may also influence regulation. Population models which accommodate variation both within and among herds in population growth parameters are necessary, even in mild climates, to fully understand population dynamics and manage populations.

The Saddle-billed Stork Ephippiorhynchus senegalensis exemplifies a case in conservation research in which a species is assessed as Least Concern on the IUCN Red List and the resulting consideration of low conservation priority has precluded proper scientific study. As a first step in understanding this stork's true status, we collated all available data to develop a distribution map and then investigated range-wide patterns of occurrence. The updated map greatly improves on past knowledge of the stork's distribution and helps to identify regions where range contractions have occurred, particularly in Central Africa and parts of West Africa. We found that the stork's distribution closely overlaps with protected areas and that there has been an overall increase in surface water (largely manmade water bodies)-a proxy for habitat-across the species' extent of occurrence in recent decades. While this research represents a valuable contribution to our understanding of the Saddle-billed Stork, it also highlights the need for unbiased empirical data, especially from areas that are poorly surveyed, for developing a science-based conservation status assessment.