Crested Tits prefer pine forest but not mature forest: insights from an early spring passive acoustic survey

Population declines and range contractions due to habitat loss are pervasive among nonhuman primates, with 60% of species threatened with extinction. However, the extensive vocal activity displayed by many primates makes them excellent candidates for passive acoustic surveys. Passive acoustic survey data is increasingly being used to support occupancy models, which have proven to be an efficient means of estimating both population trends and distributions. Passive acoustic surveys can be conducted relatively quickly and at broad scales, but efficient audio data processing has long proven elusive. The machine learning algorithm BirdNET was originally developed for birds but was recently expanded to include nonavian taxa. We demonstrate that BirdNET can accurately and efficiently identify an endangered primate, the Yucatán black howler monkey (Alouatta pigra), by sound in passive acoustic survey data (collected in southeastern Chiapas, Mexico), enabling us to use a single-season occupancy model to inform further survey efforts. Importantly, we also generated data on up to 286 co-occurring bird species, demonstrating the value of integrated animal sound classification tools for biodiversity surveys. BirdNET is freely available, requires no computer science expertise to use, and can readily be expanded to include more species (e.g., its species list recently tripled to >3000), suggesting that passive acoustic surveys, and thus occupancy modeling, for primate conservation could rapidly become much more accessible. Importantly, the long history of bioacoustics in primate research has yielded a wealth of information about their vocal behavior, which can facilitate appropriate survey design and data interpretation.

Many fish species produce sounds as a part of their reproductive behavior. Using passive acoustic recording approaches, these sounds can be used to document temporal and spatial patterns of reproductive activity of fish populations. We conducted an 11-month passive acoustic survey at three different locations off the coasts of Georgia (40 km north of Grays Reef National Marine Sanctuary) and North Carolina (Onslow Bay) to understand the spawning phenology of two species of acoustically active fishes: black drum (Pogonias cromis) and toadfish (Opsanus sp.). Due to the depth of the recording locations, we could not confirm whether the toadfish calls were produced by O. tau, or another Opsanus species. Both taxa have readily identifiable, distinct sounds. Chorusing sounds from both species were detected at all three Georgia sites and at two of the three North Carolina locations; chorusing duration of both species was greater in Georgia. The onset and duration of chorusing activity for both species was correlated with water temperature. The abundance of calls of these two species from field recordings further demonstrates the value of long-term passive acoustic surveys for understanding the reproductive seasonality of acoustically active fish species.

The goal of this study was to develop a passive acoustic survey protocol to identify spawning habitats of sciaenid fishes. Based on comparisons of recordings of captive-fish and field recordings of species-specific courtship sounds, spawning areas of red drum, weakfish, spotted sea trout, and silver perch (Family Sciaenidae) have been identified in Pamlico Sound, NC. Sciaenid sounds were recorded using either a portable hydrophone deployed from a boat or timer-operated sonobuoys. Loudness of mating choruses of weakfish and silver perch was strongly correlated with the abundance of pelagic sciaenid-type eggs, suggesting that these areas were used for spawning. Sonobuoy recordings showed that weakfish spawned only in the high-salinity habitats near the inlets, spotted sea trout spawned predominantly in the low-salinity areas near the river mouths, silver perch spawned in both high- and low-salinity areas, and red drum spawned most commonly in low-salinity areas, but only in September. The loudness of mating choruses of silver perch was diminished when vocalizing bottlenose dolphins were present in the area around sonobuoys or when recordings of signature whistles were played back. Such ‘‘acoustical avoidance’’ behavior causes variation in sound pressure levels and could lead to lower estimates of abundance of spawning adults when conducting passive acoustic surveys.

We conducted a preliminary passive acoustic survey of the occurrence of freshwater drum, Aplodinotus grunniens, in the New York State Canal System (NYSCS) to demonstrate the usefulness of underwater sound monitoring in invasive species studies. Data from known populations of freshwater drum in Dale Hollow Reservoir and J. Percy Priest Lake in Tennessee and Lake Champlain in New York were used to validate freshwater drum call characteristics. Similar to more well studied marine members of the Sciaenidae, freshwater drum calls are composed of highly variable trains of 1–119 knocks call−1 (mean = 25 knocks call−1), a mean knock period of 33 knocks s−1, mean peak frequency of 400 Hz, and mean duration of 0.8 s. The occurrence of drum chorus calls at many locations within the NYSCS indicates likely spawning throughout the system, and suggests the possibility that individuals have invaded the Hudson River from native populations of Lake Champlain, Lake Erie, and Lake Ontario. We point out that the species has been excluded from the east coast of North America throughout history by geographic barriers, and it would have been impossible for the species to gain entrance to the Hudson without the NYSCS, or direct introduction, and thus it is a true invasive which will likely have a dramatic impact on the Hudson River ecosystem. We suggest that freshwater drum most likely also invaded Lakes Oneida, Onondaga, Cayuga and Seneca through the NYSCS. We conclude that passive acoustic surveys are a highly effective non-invasive tool to monitor the distribution of soniferous invasive organisms in aquatic systems, and promise to be especially useful in documenting the future spread of freshwater drum in the Hudson River system.

Assessment of reptile response to habitat degradation in arid and semi-arid regions

Field studies have demonstrated interspecific niche separation between the Willow Tit Parus montanus and the Crested Tit P. cristatus in mixed-species flocks using mature coniferous forest. The dominant Crested Tit prefers the upper parts in pine, while the Willow Tit forages lower in the canopy. Foraging niche shifts of these species were studied when they foraged alternately in mature pine forest and in areas with saplings. In the saplings, where flying predators are unable to attack prey in the lower part of the canopy because of the dense branch structure there, Crested Tits switched to forage in the lower parts. As the subordinate species, Willow Tits foraged lower in the mature forest and higher up in the saplings, thus in both cases using more exposed parts of the canopy. Predation risk from Sparrowhawks Accipiter nisus seemed to be high. Since Crested Tits used the safest sites in both habitats, tits seem able to evaluate predation risk and adjust their habitat use. The spatial segregation of foraging niches in flocks of wintering tits can be explained by their response to habitat gradients in predator exposure.

Habitat loss, fragmentation and degradation effects on small mammals: Analysis with conditional inference tree statistical modelling

Anthropogenic habitat fragmentation has well-established deleterious effects on populations and communities of native vertebrates, but the mechanisms underlying population decline under fragmentation remain poorly understood. Most studies of vertebrates in anthropogenically-fragmented habitats have focused on population density, demographics or fecundity. Relatively little attention has been given to indices of health status, body condition or physiological stress. In this study, 30 populations of a small marsupial, the agile antechinus (Antechinus agilis), living in anthropogenically-fragmented forest patches were sampled in two years (2007 and 2008). Immediately after sampling in each fragment, a population in a matched control site in similar, but unfragmented forest (a 'pseudofragment') was sampled. Indices of population density (relative abundance), estimated fat reserves (mass-size residuals), health status (erythrocyte variables), parasite load (simplified ectoparasite counts and eosinophil percentages) and chronic physiological stress (total and differential immune cell counts) were examined. Relative abundances were lower and parasite load indices higher in fragmented than continuous forest. Fragment populations displayed indications of regenerative anaemia, which is related to poor health status and potentially caused by chronic stress, frequent blood loss or heavy parasite loads. Estimated fat reserves were higher in fragment than continuous forest populations. Nonetheless, differential leukocyte counts suggested that chronic physiological stress was greater (i.e. greater neutrophil-to-lymphocyte ratios) (N:L) in populations in fragments. Anthropogenic fragmentation effects are not often distinguished in the ecological literature from those of co-occurring processes, such as habitat loss and degradation. To investigate the effects of these processes, environmental factors were examined that were thought to have a potential influence on agile antechinus (e.g. fragment patch core area, proportion of edge habitat, isolation, woody debris abundance, shrub density etc). Relative abundance of agile antechinus was positively correlated with forest patch core area and native tree-cover within a 0.5 km radius of a study site. Estimated fat reserves, particularly in males, were greater in populations in fragments with a smaller core area, but statistical modelling indicated that the effect was an indirect one: males had greater estimated fat reserves where the abundance of conspecifics was lower, suggesting that this metric was responding to intraspecific competition and per capita food availability. Health status, indexed by erythrocyte indicators of regenerative anaemia,was positively associated with greater microhabitat heterogeneity, and abundance of shrubs, logs and native trees other than Eucalyptus species. Female abundances were lower in edge habitat (< 60 m from edge) than in fragment interiors (> 80 m from edge), and females had higher chronic stress indicators (N:L) where fragments were more highly dissected by edge habitat. Although parasite load indices and male N:L were higher in fragment than continuous forest sites, the environmental factors responsible were not identified. The study has demonstrated that anthropogenic habitat fragmentation, loss and degradation can have broadly negative effects on a native vertebrate, not only on its population density, but also in terms of health status and chronic physiological stress. This is a serious concern from a conservation management perspective, because chronic stress has pronounced fitness-reducing effects in vertebrates, including reduced reproductive investment, fecundity and survivorship.

We assessed habitat preference of a lynx (Lynx canadensis) population through 8 years of a snowshoe hare (Lepus americanus) cycle. Seventy-four percent of our southern Yukon study area was approximately 30-year-old regenerating forest resulting from a large wildfire. The study area was not trapped and lynx density was very high compared with other populations in North America. Contrary to our prediction, there was no discernable shift in habitat preference through the hare cycle; however, our habitat types were coarsely mapped and our radiolocations relatively inaccurate. Lynx may have altered their habitat preferences at finer scales (for patches <2 ha). Lynx showed strong preference for regenerating habitats over mature white spruce (Picea glauca) and alpine–subalpine. Lodgepole pine (Pinus contorta) dominated regenerating stands were preferred over spruce–willow (Salix spp.) stands of equal age. Riparian willow stands were also preferred over mature spruce forest and alpine. Lynx used riparian willow stands more in winter, but we detected no other shifts in habitat preference between snow-free and winter periods. We did not detect any difference in habitat preference between sexes. Independent juveniles made greater use of mature forest and perhaps riparian willow than adults, but no other difference in preference between the two age groups was noted. Lynx preference for regenerating habitat over mature forest suggests that burns will benefit lynx, especially if the regenerating community is pine dominated. Logging will only likely provide similar benefits if a dense pine understory results, which is unlikely in intensively managed stands. The suppression of forest fires in recent decades may have contributed to the decline of lynx numbers in the south of their range.

Spatial distributions of coral reef fish species are potentially determined by habitat preferences and behavioural interactions. However, the relative importance of these factors and whether or not behavioural interactions reinforce or disrupt habitat associations are poorly understood. This paper explores the degree to which habitat and social preferences explain the association that three common coral reef cardinalfish species (Zoramia leptacanthus, Archamia zosterophora and Cheilodipterus quinquelineatus; family Apogonidae) have with coral substrata at Lizard Island, Great Barrier Reef. At diurnal resting sites, species were strongly associated with branching corals, with 80–90% of each species inhabiting one branching coral species, Porites cylindrica. Species were also highly gregarious, forming large con-specific and hetero-specific aggregations in coral heads, potentially reinforcing habitat associations. Three-way choice experiments were conducted to test fishes habitat preferences for living coral over dead substrata, for particular coral species, and the influence of gregarious behaviour on these habitat choices. The strength of habitat preferences differed among species, with Z. leptacanthus preferring live coral and P. cylindrica, A. zosterophora preferring P. cylindrica, whether live or dead and C. quinquelineatus exhibiting no preferences. All species were attracted to conspecifics, and for C. quinquelineatus and A. zosterophora, conspecific attraction resulted in stronger preferences for live corals. Gregarious behaviour also increased C. quinquelineatus associations with P. cylindrica. The relative strength of social attraction versus habitat preferences was investigated by comparing fish habitat preferences in the presence and/or absence of conspecifics. The presence of conspecifics on non-preferred rubble habitat reduced each species association with live coral. This study’s results indicate that in the field, habitat preferences and conspecific attraction combine to reinforce the association between cardinalfishes and a narrow range of coral substrata.

The formulation of effective control strategies for any pest species generally involves the study of habitat use and preference and niche width in anthropogenically transformed natural landscapes. We evaluated whether the use, habitat preference, and niche range of the Amblyomma mixtum tick changed between stages, habitats, and seasonality (dry-wet seasons 2019) on a farm in Yopal (Casanare, Colombia). The presence and relative abundance of free-living larvae, nymphs, and adults was quantified in four different habitats according to the type of vegetation cover (Riparian Forest, Cocoa Crop, King Grass Crop, and Star Grass Paddock). Habitat availability was estimated, environmental variables were analyzed, and various indices of habitat use and preference, and niche width were calculated. A. mixtum’s habitat use and preference, and niche width changed between stages, habitat types, and time of the year. The total abundance of A. mixtum was an order of magnitude greater in the dry season than the wet season. In the dry season, all stages used all habitats, while A. mixtum adults used all the habitats in both seasons. In the dry season, nymphs and larvae preferred three out of the four habitats, while adults preferred the King Grass Crop. In the wet season, nymphs and larvae preferred two habitats, whereas the adults preferred the King Grass Crop. The value of the niche width index was high for larvae, nymphs, and adults in the dry season, while it was high only for adults in the wet season. Thus, A. mixtum’s vast environmental tolerance and niche breadth allows the species to use and colonize changing habitats (unstable or temporary) with fluctuating environmental conditions (e.g., King Grass Crop), potentially keeping a stable population over time and making it an extremely resistant species. However, the wet flooding season in Yopal may exceed A. mixtum’s stages’ tolerances.

Altogether, 4,008 sand flies belonging to seven species were collected over a period of one year in the micro-habitats of a single canyon in the Carmel Mountain ridge. The three most abundant were P. arabicus, P. tobbi, and P. simici. Our results suggest that none of the seven sand fly species was indifferent to the heterogeneity of the microenvironment inside the canyon. Apart from the rare P. perfiliewi, which was only collected on the upper part of the south-facing slope, and P. tobbi, which clustered on the north-facing slope, the bulk of the other sand flies were caught on the bottom of the canyon. During the summer, the catches of all sand fly species increased to reach their maximum number in August and September. In April and May, there was lush vegetation and humidity, so species were distributed evenly throughout their habitats. With the onset of summer dryness, the sand flies concentrated in the humid habitats. The rate of concentration was essentially higher for males than for females, and this variation may result from differences in the behavior of the two sexes. During our study, none of the 2,318 dissected female sand flies were positive for Leishmania promastigotes.

The chital, Axis axis, constitutes one of Nepal's six deer species and maintains a closed population within the forest of the Institute of Forestry, Hetauda Campus. Presently, the chital population faces a range of challenges, prompting a comprehensive study encompassing population status, habitat preference analysis, and threat assessment. We utilized the pellet group count method on 74 systematic random sample plots (4×4m) within a 100×100 m grid for population estimation. Pellet presence/absence in predetermined habitat characteristics was analyzed to assess habitat preferences. Concurrently, a relative threat ranking method from household interviews was employed to evaluate existing threats. The study revealed a total chital population estimate of approximately 141 individuals, with a population density of 190 individuals per km2. Their habitat preference showed an affinity towards areas abundant in Sal and riverine forests, along with an inclination towards locations further from roads within the forested areas. Primary threats to the chital population encompassed attacks from feral dogs, illegal hunting, and habitat degradation mainly due to invasive alien plant species. This study shows that with effective management of the feral dogs, mitigation strategy to control illegal hunting with the help of local authorities, and improving the habitat conditions concerning their preferences, the chital population has the potential to continue growing in the coming years.

Worldwide, anthropogenic habitat loss and degradation have led to substantial biodiversity declines. Preserving biodiversity requires an understanding of how habitat loss and degradation interact to impact species populations, and how land-use decisions can limit these losses. We present a mathematical partitioning of changes in landscape-level population abundance in response to land-use change using a modified version of the Price equation from evolutionary biology. The Price equation partitions changes in species abundance into multiple drivers related to habitat loss, habitat degradation, and their interaction. We describe its development and exemplify its applicability using simulated data. Applying the Price equation to simulated data reveals the roles of habitat loss, habitat degradation, and their interaction in driving population change in patchy landscapes undergoing complex land-use change processes. The Price equation is a theoretical tool that may enhance our understanding of the effects of land-use change on populations by accounting for the specific processes by which land-use change operates across landscapes.

Responses of flora and fauna in wet eucalypt production forest to the intensity of disturbance in the surrounding landscape