Impacts of ecological mismatches should be most pronounced at points of the annual cycle when populations depend on a predictable, abundant, and aggregated food resource that changes in timing or distribution. The degree to which species specialize on a key prey item, therefore, should determine their sensitivity to mismatches. We evaluated the hypothesis that the effects of ecological mismatch during migratory stopover are mediated by a species’ foraging ecology by comparing two similar long‐distance migratory species that differ in their foraging strategies during stopover. We predicted that a specialist foraging strategy would make species more sensitive to effects of mismatch with a historically abundant prey, while an active, generalist foraging strategy should help buffer against changing local conditions. We estimated arrival times, start of mass gain, and rate of mass gain during spring stopover in Delaware Bay, USA. At this site, shorebirds feed on a temporally aggregated food resource (horseshoe crab Limulus polyphemus eggs), the timing of which is linked to water temperature; red knot (Calidris canutus rufa) specializes on these while the ruddy turnstone (Arenaria interpres) feeds more generally. We used a hierarchical nonlinear model to estimate the effect of mismatch between shorebird arrivals and timing of crab spawning on the timing and rate of mass gain over 22 yr. In years with cooler water temperature, crabs spawned later, which was associated with later and faster mass gain for the knots. Turnstones exhibited less inter‐annual variation in the timing and rate of mass gain than knots, and we found no relationship between mass gain dynamics and the availability of horseshoe crab eggs for this generalist species. Long‐distance migrants rely on predictable resources en route and even when these linkages are simple and predictable, populations can be vulnerable to change; these results suggest that generalist foraging strategies may buffer migratory species against phenological mismatch. We provide a framework to evaluate population responses to changes in prey phenology at sites vulnerable to climatic change.

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Hand‐arm vibration syndrome (HAVS) is an irreversible neurodegenerative, vasospastic, and musculoskeletal occupational disease of workers who use powered hand tools. The etiology is poorly understood. Neurological symptoms include numbness, tingling, and pain. This study examines impact hammer vibration‐induced injury and recoverability of hair mechanosensory innervation. Rat tails were vibrated 12 min/d for 5 weeks followed by 5 week recovery with synchronous non‐vibrated controls. Nerve fibers were PGP9.5 immunostained. Lanceolate complex innervation was compared quantitatively in vibrated vs sham. Vibration peak acceleration magnitudes were characterized by frequency power spectral analysis. Average magnitude (2515 m/s2, root mean squared) in kHz frequencies was 109 times that (23 m/s2) in low Hz. Percentage of hairs innervated by lanceolate complexes was 69.1% in 5‐week sham and 53.4% in 5‐week vibration generating a denervation difference of 15.7% higher in vibration. Hair innervation was 76.9% in 5‐weeks recovery sham and 62.0% in 5‐week recovery vibration producing a denervation difference 14.9% higher in recovery vibration. Lanceolate number per complex (18.4 ± 0.2) after vibration remained near sham (19.3 ± 0.3), but 44.9% of lanceolate complexes were abnormal in 5 weeks vibrated compared to 18.8% in sham. The largest vibration energies are peak kHz accelerations (approximately 100 000 m/s2) from shock waves. The existing ISO 5349‐1 standard excludes kHz vibrations, seriously underestimating vibration injury risk. The present study validates the rat tail, impact hammer vibration as a model for investigating irreversible nerve damage. Persistence of higher denervation difference after 5‐week recovery suggests repeated vibration injury destroys the capability of lanceolate nerve endings to regenerate.

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Hand Arm Vibration Syndrome (HAVS) is an occupational disease affecting 50% of riveting hammer operators after 10 years of work. 1 Current international standards (ISO 5349) seeking to protect workers from occupational vibration are not effectively predicting HAVS onset. 1-3 Scarce research has been done which investigates the long term effects of riveting hammer vibration exposure and nerve regeneration. The present study examines the effects of typical occupational vibrational exposure on cutaneous mechanosensory peripheral nerve populations (lanceolates) and as well as nerve bodies (dorsal root ganglion) that are responsible for nerve regeneration. A piezoelectric sensor-based data acquisition system is used rather than the traditional laser vibrometer. Although data analysis is not complete, current results show that the piezoelectric system is a viable means of vibrational analysis for both laboratory and workplace research. It records dominant kilohertz frequencies in the riveting hammer vibration signal which are currently overlooked by ISO 5349.