Effectiveness of population-based recovery actions for threatened southern mountain caribou.

Habitat loss is affecting many species, including the southern mountain caribou (Rangifer tarandus caribou) population in western North America. Over the last half century, this threatened caribou population's range and abundance have dramatically contracted. An integrated population model was used to analyze 51 years (1973-2023) of demographic data from 40 southern mountain caribou subpopulations to assess the effectiveness of population-based recovery actions at increasing population growth. Reducing potential limiting factors on threatened caribou populations offered a rare opportunity to identify the causes of decline and assess methods of recovery. Southern mountain caribou abundance declined by 51% between 1991 and 2023, and 37% of subpopulations were functionally extirpated. Wolf reduction was the only recovery action that consistently increased population growth when applied in isolation, and combinations of wolf reductions with maternal penning or supplemental feeding provided rapid growth but were applied to only four subpopulations. As of 2023, recovery actions have increased the abundance of southern mountain caribou by 52%, compared to a simulation with no interventions. When predation pressure was reduced, rapid population growth was observed, even under contemporary climate change and high levels of habitat loss. Unless predation is reduced, caribou subpopulations will continue to be extirpated well before habitat conservation and restoration can become effective.

Idiopathic laryngeal spasm: management and long-term outcome.

Idiopathic laryngeal spasm (ILS) is an uncommon disorder characterised by brief episodes of stridor, occurring at any time. Subsequent outpatient ENT examination is normal. These episodes cause considerable anxiety for both patient and physician. Little is known about the initiating event(s) in this condition or the long-term outcome. Using a combination of telephone and postal questionnaires with case note review, we have reviewed a cohort of 21 patients with this diagnosis managed by the senior author over the last 15 years. None of the 19 patients who responded were worse; 13 (68%) described improvement or complete resolution of symptoms. ILS is difficult to classify in the spectrum of vocal cord disorders, but appears distinct to those previously described. The condition responds well to a conservative management approach of reassurance and counselling.