Biology subjects

Lambert, H.

Publications and source records attributed to Lambert, H..

3 recordsLinked to original sources

bioRxiv2025

Passive Acoustic Monitoring within the Northwest Forest Plan Area: 2023 Annual Report

Here we document progress in implementing large-scale passive acoustic monitoring across the Northwest Forest Plan area to track population trends of northern spotted owls (Strix occidentalis caurina), barred owls (S. varia), marbled murrelets (Brachyramphus marmoratus), and a broad array of forest-adapted wildlife. In 2023, we deployed 4,012 autonomous recording units across 1,009 randomly selected 5-km{superscript 2} hexagons, generating nearly 2.2 million hours of recordings, representing approximately 1 petabyte of acoustic data. These data were processed with PNW-Cnet v5, the latest version of our convolutional neural network model, trained on 135 sound classes representing over 80 species and environmental sounds. Model performance demonstrated high precision for focal species and many additional taxa, substantially reducing manual review effort while enabling broad-scale biodiversity assessments. Results confirmed northern spotted owl detections in all 20% sample areas, with occupancy varying geographically and declining notably in the Tyee study area. Barred owls were widely detected, with the highest prevalence in Oregon and Washington and comparatively lower occupancy in California. Marbled murrelets were consistently detected in coastal areas, particularly the Olympic Peninsula and Oregon Coast Range. Beyond these focal species, PAM and PNW-Cnet generated robust datasets for a wide range of birds, mammals, and disturbance indicators, underscoring the value of random-site, multi-species monitoring. The 2023 field season marked the first full implementation of the 2% + 20% NWFP sampling design, expanding monitoring coverage while strengthening collaborations with federal and state partners. These efforts provide the foundation for long-term, cost-effective wildlife monitoring and inform conservation strategies in dynamic forest ecosystems.

ecology↗

bioRxiv2025

Honeybees collect pollen from the buzz-pollinated flowers of invasive Solanum elaeagnifolium in Northern Greece

Around 6% of flowering plants, including most solanaceous species, have flowers specialized for buzz-pollination (sonication). The poricidal anthers of these flowers release pollen in response to frequency-specific vibrations, which buzz-pollinating bees, including bumble bees and many solitary bees, generate via rapid oscillation of flight muscles. Honeybees are incapable of sonication and typically avoid visiting buzz-pollinated plants, although they have previously been observed to scavenge residual pollen from petals of buzz-pollinated flowers in natural settings. Here, we report a novel interaction in which honeybees consistently visit and extract pollen from flowers of Solanum elaeagnifolium (silverleaf nightshade) within a large invasive plant population in Northern Greece. We postulate that honeybee foraging effort on S. elaeagnifolium reflects the shortage of alternative floral resources at the peak of the Mediterranean summer, consistent with observations for pollen-starved bees in captivity. This newly established behavioral shift of honeybees may convey important implications for plant invasions, particularly under climate change, and requires further investigation for untangling its ultimate drivers.

ecology↗

bioRxiv2025

Fine-scale variation in pollen availability influences Bombus terrestris colony behaviour, development and fitness.

Climate change threatens the long-established synchronization of seasonal pollinator activity and flowering time. Bumble bees are particularly vulnerable to these shifts, with resource availability playing a significant role in colony establishment and success. Recently, we documented a mechanism whereby pollen-deprived bumble bees deliberately damaged plant leaves, speeding up the production of flowers in two different species. However, it is unknown whether bumble bees obtain a benefit through this behaviour, both on a spatial and temporal scale. In the current study, we evaluate the effects of pollen availability on colony development, behaviour and reproductive fitness in Bombus terrestris using semi-natural and laboratory experiments. We find that the close proximity of flowers has significant effects on reproductive investment and output of B. terrestris colonies in a small-scale rooftop experiment. Moreover, we find that small shifts in the timing of pollen availability (5 days) shape the behaviour and development of the first generation of offspring, with significant carry-over effects on reproductive fitness for B. terrestris microcolonies. This suggests that small changes in the distribution of food may have significant impacts on colony success that cannot be compensated for over the course of the season. Furthermore, our findings suggest bumble bee colonies can feasibly profit by altering the timing of pollen resources, even by a few days.

ecology↗