Increased growth of the mid-continent population of Lesser Snow Geese (LSGO) has led to the degradation of coastal salt marsh and sedge meadow habitats across Canadian Arctic and sub-Arctic ecosystems. It is believed that a human-induced trophic cascade caused by agricultural habitat modification along migratory routes and wintering grounds has contributed to the increase in LSGO numbers, which has resulted in the alteration of habitat quality and connectivity along northern breeding and stopover sites used by various avian species. This habitat degradation has been shown to decrease the presence and temporal persistence of ground-nesting passerine and shorebird species at a local level and may lead to decreases of Arctic / sub-Arctic breeding avian species across landscapes that LSGO utilize and degrade. In 1999, four paired study plots were established, and used in conjunction with a single study plot from 1976, in order to measure the composition of habitat parameters (barren ground extent; graminoid and shrub cover) and to estimate the number of avian nests found in these plots. Using this historical data along with our findings from 2010 and 2011, our main objectives were to: 1) document the change in the aforementioned habitat parameters over time; 2) estimate the local nesting occupancy rates of the common Savannah Sparrow (SAVS), a robust and adaptable ground nester; and 3) determine which habitat variables are indicative of the rates of change and occurrence of nesting by SAVS within the study plots. By using ANOVA, linear mixed effects, and multi-state occupancy models, results suggest that an increase in barren ground, decreases in shrub and graminoid cover, and a loss of connectivity between suitable nesting patches has led to a 10% (λ = 0.90) annual decline in the probability that SAVS nesting occurred across the study plots from 1999 to 2010. These model results may be used to estimate long-term trends in persistence of breeding SAVS and other similar ground-nesting avian species that share habitats with LSGO along Arctic and sub-Arctic ecosystems. (93 pages)

A growing body of research focuses on how background sounds shape and alter critical elements of animals’ lives, such as foraging behavior, habitat use, and ecological interactions (Bradbury & Vehrencamp, 2011; Barber et al., 2010; Kight & Swaddle, 2011; Shannon et al., 2016). Much of this research has centered on the effects of anthropogenic noise (Dominoni et al., 2020; Francis & Barber, 2013; Ortega, 2012; Swaddle et al., 2015), but recent studies have also revealed that natural sound sources can influence animal behavior (Davidson et al., 2017; Le et al., 2019). Natural sounds, such as crashing surf, can create conditions where signaling and listening are difficult, but how this influences different species’ ecological interactions are unknown. To study the effects of crashing surf sound we experimentally introduced landscape-level acoustic playbacks where surf sound was not naturally present to create a “phantom ocean”. Phantom ocean treatment sites were employed alongside higher frequency “shifted” treatment sites to test for frequency-dependent effects, “real ocean” sites where surf sound was endemic, and ambient control sites. The phantom and shifted treatments were played continuously during the spring and summer of 2017-2019. Within this acoustic experimental landscape we conducted multiple studies to test the effects of crashing surf sound on animal behavior, habitat use, and ecological interactions. Through an artificial caterpillar predation experiment modeled after Roslin et al. (2017), we found that when exposed to natural sound treatments the foraging activity of rodents and arthropods increased, while that of birds declined. A potential explanation for this pattern includes taxon-specific responses reflecting different perceived risk-reward trade-offs in natural sound conditions. To follow this up we performed occupancy modeling on data collected by camera traps set within our system. We observed different responses among groups of species with different functional roles in the community for both detection (p) and occupancy (Ψ) probabilities. Our combined results indicate different species and functional groups have unique foraging behavior and patch use responses to natural sounds, likely based on their ecological interactions. Specifically, Cricetid rodents are likely more active in areas exposed to natural sounds, possibly due to lower perceived predation risk because mesocarnivores are less active. Insectivorous birds are also likely less active under natural sounds conditions, although the frequency of the sound, and the body size and diet of the bird appear influential. Together these findings suggest that natural sounds shape not only individual behavioral adjustments, but also multi-trophic, community level interactions. Our results show that natural sounds are an important driver of ecological interactions, but much remains to be uncovered. The mechanisms by which natural sounds influence individuals, populations, and many other aspects of ecology remain unexplored and provide fertile ground for future inquiry.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O sagui-da-serra-escuro (Callithrix aurita) (É.Geoffroy, 1812) é uma espécie endêmica da Mata Atlântica e ameaçada de extinção, considerada em perigo. Callithrix jacchus e C. penicillata são espécies invasoras no Estado do Rio de Janeiro, que competem com C. aurita pelos mesmos recursos, além de formarem híbridos. Nesse contexto, avaliamos a distribuição espacial das espécies de saguis (nativa e invasoras) no interior e entorno do Parque Nacional da Serra dos Órgãos (PARNASO), RJ, Brasil, através do método de playback, entrevistas, e a modelagem de ocupação e detecção. Além disso, comparamos os dados de distribuição atual com os registros de ocorrência anteriores a esse estudo. Os resultados mostraram que a população de saguis nativos e invasores presentes no interior no parque possuem probabilidade de ocupação (0,20 e 0,22), detecção (0,22 e 0,26) e abundância (12,65 e 13,68 grupos) semelhantes. A ocupação de C. aurita está relacionada às áreas do parque mais afastadas da estrada e com menor interferência humana, provavelmente pelo efeito da elevada altitude nessas regiões. Enquanto que a ocupação dos saguis invasores está relacionada à proximidade dos limites do parque e a maior interferência humana, tanto em maiores altitudes quanto em menores. Registramos o processo de hibridação entre saguis nativos e invasores, e a formação de grupos mistos entre eles, em diversos pontos da região de Petrópolis, inclusive no interior do parque, evidenciando as consequências do processo de invasão. Concluímos que a população de Callithrix aurita no PARNASO é pequena, restrita a uma única região do parque, e parte dela possui contato com grupos de saguis invasores, ou está bem próxima deles. As espécies de saguis invasores ocorrem em alguns locais no interior do parque e por todo o seu entorno. Portanto, há uma pressão dos saguis invasores em direção ao interior do PARNASO. Diante deste processo de extinção local de uma espécie endêmica, ameaçada de extinção, e com uma restrita distribuição geográfica, alertamos para a urgente necessidade de iniciar um eficiente programa de manejo das espécies de saguis invasores, juntamente com a reintrodução de grupos de Callithrix aurita. / The Buffy-tufted-ear marmoset (Callithrix aurita) (É.Geoffroy, 1812) is an endemic species of the Atlantic Forest and endangered. Callithrix jacchus and C. penicillata are invasive species in the state of Rio de Janeiro, which compete with C. aurita for the same resources, and form hybrids. In this context, we evaluated the spatial distribution of species of marmosets (native and invasive) in and around the National Park of the Serra dos Órgãos (PARNASO), RJ, Brazil, through using the playback method, interviews, modeling occupation and detection. Furthermore, we compared the actual distribution data with the occurrence of records preceding this study. The results showed that the population of native marmosets and invaders present in the park have similar occupancy probability (0,20 and 0,22), detectability (0,22 and 0,26) and abundance (12,65 and 13,68 groups). The occupancy of the C. aurita is related to the most remote areas of the park road and less human interference, probably due to high altitude in these regions. While the occupancy of the invader marmosets is related to the proximity of the park boundaries and human interference, both at higher altitudes as for minors. We recorded the process of hybridization between native marmosets and invaders, and the formation of mixed groups among them, in various parts of Petropolis, including inside the park, showing the consequences of the invasion process. We concluded that the population of Callithrix aurita in PARNASO is small, restricted to a single region of the park, and some of it has contact with groups of marmosets invaders, or is very close to them. The species of marmoset invaders occur in some places inside the park and all its surroundings. So there is pressure from invader marmosets toward the interior of PARNASO. Given this local extinction process of an endemic species, endangered, and with a restricted range, it alerts to the urgent need to initiate an effective management program of the species of marmosets invaders among the reintroduction of Callithrix aurita groups.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O sagui-da-serra-escuro (Callithrix aurita) (É.Geoffroy, 1812) é uma espécie endêmica da Mata Atlântica e ameaçada de extinção, considerada em perigo. Callithrix jacchus e C. penicillata são espécies invasoras no Estado do Rio de Janeiro, que competem com C. aurita pelos mesmos recursos, além de formarem híbridos. Nesse contexto, avaliamos a distribuição espacial das espécies de saguis (nativa e invasoras) no interior e entorno do Parque Nacional da Serra dos Órgãos (PARNASO), RJ, Brasil, através do método de playback, entrevistas, e a modelagem de ocupação e detecção. Além disso, comparamos os dados de distribuição atual com os registros de ocorrência anteriores a esse estudo. Os resultados mostraram que a população de saguis nativos e invasores presentes no interior no parque possuem probabilidade de ocupação (0,20 e 0,22), detecção (0,22 e 0,26) e abundância (12,65 e 13,68 grupos) semelhantes. A ocupação de C. aurita está relacionada às áreas do parque mais afastadas da estrada e com menor interferência humana, provavelmente pelo efeito da elevada altitude nessas regiões. Enquanto que a ocupação dos saguis invasores está relacionada à proximidade dos limites do parque e a maior interferência humana, tanto em maiores altitudes quanto em menores. Registramos o processo de hibridação entre saguis nativos e invasores, e a formação de grupos mistos entre eles, em diversos pontos da região de Petrópolis, inclusive no interior do parque, evidenciando as consequências do processo de invasão. Concluímos que a população de Callithrix aurita no PARNASO é pequena, restrita a uma única região do parque, e parte dela possui contato com grupos de saguis invasores, ou está bem próxima deles. As espécies de saguis invasores ocorrem em alguns locais no interior do parque e por todo o seu entorno. Portanto, há uma pressão dos saguis invasores em direção ao interior do PARNASO. Diante deste processo de extinção local de uma espécie endêmica, ameaçada de extinção, e com uma restrita distribuição geográfica, alertamos para a urgente necessidade de iniciar um eficiente programa de manejo das espécies de saguis invasores, juntamente com a reintrodução de grupos de Callithrix aurita. / The Buffy-tufted-ear marmoset (Callithrix aurita) (É.Geoffroy, 1812) is an endemic species of the Atlantic Forest and endangered. Callithrix jacchus and C. penicillata are invasive species in the state of Rio de Janeiro, which compete with C. aurita for the same resources, and form hybrids. In this context, we evaluated the spatial distribution of species of marmosets (native and invasive) in and around the National Park of the Serra dos Órgãos (PARNASO), RJ, Brazil, through using the playback method, interviews, modeling occupation and detection. Furthermore, we compared the actual distribution data with the occurrence of records preceding this study. The results showed that the population of native marmosets and invaders present in the park have similar occupancy probability (0,20 and 0,22), detectability (0,22 and 0,26) and abundance (12,65 and 13,68 groups). The occupancy of the C. aurita is related to the most remote areas of the park road and less human interference, probably due to high altitude in these regions. While the occupancy of the invader marmosets is related to the proximity of the park boundaries and human interference, both at higher altitudes as for minors. We recorded the process of hybridization between native marmosets and invaders, and the formation of mixed groups among them, in various parts of Petropolis, including inside the park, showing the consequences of the invasion process. We concluded that the population of Callithrix aurita in PARNASO is small, restricted to a single region of the park, and some of it has contact with groups of marmosets invaders, or is very close to them. The species of marmoset invaders occur in some places inside the park and all its surroundings. So there is pressure from invader marmosets toward the interior of PARNASO. Given this local extinction process of an endemic species, endangered, and with a restricted range, it alerts to the urgent need to initiate an effective management program of the species of marmosets invaders among the reintroduction of Callithrix aurita groups.

No description available.

Positive biotic interactions such as mutualism, commensalism and facilitation are ubiquitous in nature, but historically have received considerably less research attention than negative interactions such as competition, predation and parasitism. The paucity of research on positive interactions is particularly evident in stream ecosystems and in vertebrate communities. Stream fishes clearly provide an ideal system for advancing research on positive interactions. Many minnows (Cyprinidae) of eastern North America engage in a potentially mutualistic reproductive interaction known as nest association, in which individuals of one species (nest associates) spawn in nests constructed by host species. In nest association, hosts provide unsilted gravel substrate for spawning nest associates, and increased parental care to associate broods. High associate: host egg ratios can create a dilution effect, reducing the probability that host eggs will be preyed upon by egg predators. Nest associative interactions are common, but are relatively understudied compared to other interactions among stream fishes. The goals of this study were to apply general ecological models to this novel system to (a) gain new insight into the mechanisms structuring nest associative stream fish communities, and (b) to use inference from stream fish communities to potentially expand and improve the general ecological models. These goals required completion of three objectives, including (1) examining the influence of abiotic and biotic contexts on reproductive behavior and fitness outcomes between a cyprinid host and associate, using the biological markets model to generate predictions; (2) examining the utility of the nest web framework (previously only used for cavity nesting vertebrate communities) and the stress gradient hypothesis (previously applied almost exclusively to plant communities) for predicting which associate species spawn on nests built by various nest building species, and the consequences of these choices, respectively; and (3) using two-species occupancy modeling to determine the relative influence of biotic interactions and habitat covariates on the co-occurrence of a host and two nest associates. To accomplish these goals, I conducted a large-scale experiment to manipulate presence of mutualists (Nocomis leptocephalus, host; Chrosomus oreas, associate), egg predators (biotic context) and habitat quality (abiotic context). I conducted behavioral nest observations and conducted repeated stream fish stream fish community surveys to collect demographic data. I constructed a nest web from observational data, and implemented structural equation modeling through an information-theoretic framework to identify nest web plausibility across a large spatial extent. I tested some predictions of the stress gradient hypothesis by regressing juveniles-per-nest and a metric of cyprinid community structure on a composite measure of physical stress (scaled gradients of catchment-scale agricultural land use and catchment area). I used two-species occupancy modeling to model co-occurrence of N. leptocephalus hosts and two associates, C. oreas and Clinostomus funduloides, and used an information-theoretic framework to compare hypotheses representing the importance of biotic interactions, habitat covariates or both at determining species co-occurrence. Results corroborated some (but not all) model predictions, and identified room for improvement in each of the general models. Nest associative spawning by C. oreas was not context dependent; C. oreas did not spawn in the absence of a reproductively active male N. leptocephalus at any treatment level. However, the net fitness outcome of host and associate species was mutualistic, and the interaction outcome switched from commensalistic to mutualistic with abiotic context. N. leptocephalus reproductive success was improved by C. oreas presence in less-silted habitats, but not in heavily-silted habitats. This is most likely because broods were subject to predation in both habitat types, but were also negatively affected by siltation in silted habitats. Accordingly, egg dilution by associates was not sufficient to support a mutualistic relationship in less favorable habitats. Results suggest that the biological markets model may be a useful tool for predicting fitness outcomes of nest associative mutualism, but may not be as useful for predicting the behavioral outcomes of obligate mutualisms. Future applications of the biological markets model should carefully consider species traits, specifically the degree to which trading behavior is obligate for participants. Future work with this model will yield more insight by considering highly facultative associates. Nest webs constructed from nest observational data suggested an interaction topology in which strong (nearly-obligate) associates relied most frequently on N. leptocephalus nests, and less frequently on nests constructed by Campostoma anomalum. Weak (facultative) associates were seldom associated with nests constructed by either species, and probably spawned before hosts began nesting activity. Structural equation models corroborated this topology throughout the New River basin, although some less-supported model evidence specified some nest association by weak associates. Juveniles-per-nest of strong associates responded positively to physical stress, while this metric for other cyprinid reproductive groups showed no relationship. Proportional representation of Nocomis and strong associates also increased predictably with physical stress. This study suggests that the nest web framework can be informative to systems outside the ones for which it was developed; future studies may be able to use this framework to better understand the role of habitat-modifying species in communities other than cavity nesting terrestrial vertebrates and nest associative stream fishes. This work extended the nest web framework by (a) modeling the outcomes of interactions instead of the interactions themselves, and (b) by using structural equation modeling to test nest web predictions with an information-theoretic framework. This study also suggests that the stress gradient hypothesis can be useful for understanding interaction dynamics in vertebrate communities; this represents the first direct evidence that this model can be used in vertebrate communities. Further, I demonstrate that the stress gradient hypothesis may be extended to predict community structure. However, more research in a diversity of systems will be needed to determine the extent to which this can be applied. This study provides some of the first evidence of large-scale positive co-occurrence patterns in vertebrates. However, the precise roles of habitat covariates and biotic interactions were species-specific. Occupancy results suggest that co-occurrence between N. leptocephalus and nest associate C. funduloides is driven only by reproductive behavioral interactions. Alternatively, evidence suggests that co-occurrence between N. leptocephalus and C. oreas is driven by both nest association and habitat covariates. That two-species occupancy modeling can be a useful tool for comparing difficult-to-test hypotheses involving biotic interactions at large spatial scales. This study represents the first quantitative, multi-scale treatment of positive interactions in stream ecosystems. This study demonstrates that applying general ecological models to stream fish communities can yield new insights about both the study system and the models themselves. While models of negative interactions, food webs and dispersal have been applied to stream fishes, we stand to gain much ground by also considering positive biotic interactions. In doing so, stream fish ecologists will also be able to contribute to the advancement of general ecology, and thus raise awareness for these understudied ecosystems and taxa. / Ph. D.

L’écologie du Desman des Pyrénées (Galemys pyrenaicus), mammifère semi-aquatique endémique de la péninsule ibérique et des Pyrénées, demeure encore très peu connue. Les objectifs de cette thèse, dans le cadre d’un Plan National d’Actions, ont été d’identifier les variables environnementales agissant sur la répartition de l’espèce à différentes échelles spatiales, en considérant sa détectabilité imparfaite (i.e. fausses absences et fausses présences). Une probabilité de détection élevée, mais spatialement hétérogène à l’échelle des Pyrénées françaises, a été mise en évidence. La distribution du Desman des Pyrénées s’est également révélée spatialement structurée et majoritairement influencée par des facteurs propres aux milieux aquatiques, mais en forte régression depuis les années 80. Ces résultats ont permis de proposer des mesures de conservation pour cette espèce menacée. / The ecology of the Pyrenean desman (Galemys pyrenaicus), a small semi-aquatic mammal endemic to the Iberian Peninsula and the Pyrenees, remains still largely unknown. The aim of this PhD thesis conducted within the framework of a National Action Plan was to identify the environmental variables influencing the Desman distribution at various spatial scales, by accounting for its imperfect detection (i.e. false absences and false presences). A high, but spatially heterogeneous at the French Pyrenees extent, probability of detection was highlighted. The distribution of the Pyrenean Desman was also emphasized to be spatially structured and mainly influenced by aquatic factors, but severely contracting for the last 25 years. These results enabled to suggest conservation measures for this endangered species.