The implications of vehicle collisions for the Endangered endemic Zanzibar red colobus Piliocolobus kirkii

Roads affect wildlife in a variety of negative ways. Road ecology studies have mostly concentrated on areas in the northern hemisphere despite the potentially greater impact of roads on biodiversity in tropical habitats. Here, we examine 4 years (January 2016–December 2019) of opportunistic observations of mammalian roadkill along a road intersecting Jozani-Chwaka Bay National Park, Unguja, Zanzibar. In particular, we assess the impact of collisions on the population of an endemic primate, the Endangered Zanzibar red colobus Piliocolobus kirkii. Primates accounted for the majority of roadkill in this dataset. Monthly rainfall was not associated with roadkill frequency for mammals generally, nor for the Zanzibar red colobus. No single age–sex class of colobus was found dead more often than expected given their occurrence in the local population. The overall effect of roadkill on colobus populations in habitats fragmented by roads is unknown given the lack of accurate, long-term life history data for this species. Our findings suggest that mortality from collisions with vehicles in some groups of colobus is within the range of mortality rates other primates experience under natural predation. Unlike natural predators, however, vehicles do not kill selectively, so their impact on populations may differ. Although a comparison with historical accounts suggests that the installation of speedbumps along the road near the Park's entrance has led to a significant decrease in colobus roadkill, further actions to mitigate the impact of the road could bring substantial conservation benefits.

Size Selective Harvesting Does Not Result in Reproductive Isolation among Experimental Lines of Zebrafish, Danio rerio: Implications for Managing Harvest-Induced Evolution

Size-selective mortality is common in fish stocks. Positive size-selection happens in fisheries where larger size classes are preferentially targeted while gape-limited natural predation may cause negative size-selection for smaller size classes. As body size and correlated behavioural traits are sexually selected, harvest-induced trait changes may promote prezygotic reproductive barriers among selection lines experiencing differential size-selective mortality. To investigate this, we used three experimental lines of zebrafish (Danio rerio) exposed to positive (large-harvested), negative (small-harvested) and random (control line) size-selective mortality for five generations. We tested prezygotic preferences through choice tests and spawning trials. In the preference tests without controlling for body size, we found that females of all lines preferred males of the generally larger small-harvested line. When the body size of stimulus fish was statistically controlled, this preference disappeared and a weak evidence of line-assortative preference emerged, but only among large-harvested line fish. In subsequent spawning trials, we did not find evidence for line-assortative reproductive allocation in any of the lines. Our study suggests that size-selection due to fisheries or natural predation does not result in reproductive isolation. Gene flow between wild-populations and populations adapted to size-selected mortality may happen during secondary contact which can speed up trait recovery.

Gone in 40 years, the curious case of the Himalayan Quail: an attempt at rediscovery and implications for conservation

Himalayan Quail (Ophrysia superciliosa) is a Galliforme species currently classified as Critically Endangered by the IUCN. Given the fact that the species has only been recorded over a period of 40 years in the 19th century, this classification needs more scrutiny. The aim of this study was to explore the possibility of detecting the species in their known historical distribution in the lower Himalayas, and understand if possible, the factors which led to their decline or extinction. The potential habitats in districts of Nainital and Dehradun of Uttrakhand (India), where the species which has been recorded between 1836 to 1876, have been scoured thoroughly insofar as logistics and other factors permitted using trail and point transects. We did not detect any sign of the species in any of the areas, thereby corroborating the results of past surveys/expeditions in search of this species. Domesticated/feral species (grazing pressure and hunting by dogs), natural predation by species such as Yellow-throated Marten (Martes flavigula), hunting by humans, population growth and resulting land-use change, biogeochemical events, and tourism may all have contributed in varying degrees to their decline or extinction. It was found that most, if not all, proposals of strategies to find the species have been thus far unemployed or futile. We suggest improving the chances of re-discovering this species using tools such as molecular/genetic analysis and Unmanned Aerial Vehicles. Management recommendations include stress on grazing laws, sterilization of dogs, awareness about unchecked human population growth and measures for limiting the effects of unsustainable tourism.

The impact and implications of vehicle collisions on the endangered and endemic Zanzibar red colobus (Piliocolobus kirkii)

Roads can affect wildlife in a variety of negative ways. Studies of road ecology have mostly concentrated in the northern hemisphere despite the potentially greater impact on biodiversity that roads may have in tropical habitats. Here, we examine a 4-year opportunistic dataset (January 2016 – December 2019) on mammalian roadkill observed along a road intersecting Jozani-Chwaka Bay National Park, Unguja, Zanzibar. In particular, we assess the impact of collisions on the population of an endangered and endemic primate, the Zanzibar red colobus (Piliocolobus kirkii). Primates accounted for the majority of roadkill. Monthly rainfall variation was not associated with roadkill frequency for mammals and specifically for the Zanzibar red colobus. No single age-sex class of colobus was found dead more often than expected given their availability in the local population. The exact effect of roadkill on colobus populations in habitats fragmented by roads is unknown given the lack of accurate, long-term life history data for this species. However, the frequency of kills documented in this study suggests further mitigation measures may be important. Our data show that mortality from collisions with vehicles in some groups of colobus are comparable to rates of mortality experienced by other primate populations from natural predation. Unlike natural predators, however, vehicles are not ‘selective’ in their targeting of ‘prey’. The long-term implications of such a ‘predation regime’ on this species remain to be established.

Predaceous Diving Beetles (Coleoptera: Dytiscidae) May Affect the Success of Amphibian Conservation Efforts

The role of invertebrate predation in shaping vertebrate communities is often underestimated or overlooked, which has resulted in the lack of their recognition in conservation planning. This is evident with predaceous diving beetles (Coleoptera: Dytiscidae) which are often the top predator in many aquatic freshwater habitats. During weekly monitoring of a compensatory habitat reintroduction for an endangered frog species, a group of a dozen adult diving beetles were encountered attacking and quickly dismembering and consuming a tadpole. A single adult diving beetle was also discovered burrowing its head deep inside and consuming a tadpole approximately three to four times its size. Although Dytiscidae are known to occasionally consume vertebrates such as tadpoles, adults are typically considered scavengers, and this communal predatory behavior and feeding method have not been previously documented. Besides these interesting novel behaviors, these observations may have implications for amphibian conservation since management efforts are not typically concerned with naturally occurring ubiquitous threats such as those from small invertebrate predators, as it is rarely been observed in nature. However, this may be perhaps due to their ability to consume prey rapidly, especially if predating in groups. Although amphibian conservation plans expect some losses from natural predation, diving beetles may affect conservation efforts such as captive breeding and reintroductions with populations already on the threshold of extinction and where every individual critical to success.

Predaceous Diving Beetles (Coleoptera: Dytiscidae) May Affect the Success of Amphibian Conservation Efforts

During weekly monitoring of a compensatory habitat reintroduction for an endangered frog species, a group of a dozen adult diving beetles (Coleoptera: Dytiscidae) were encountered attacking and quickly dismembering and consuming a tadpole. A single adult diving beetle was also discovered burrowing its head deep inside and consuming a tadpole approximately three to four times its size. Although Dytiscidae are known to occasionally consume vertebrates such as tadpoles, adults are typically considered scavengers, and this communal predatory behavior and feeding method have not been previously documented. Besides these interesting novel behaviors, these observations may have implications for amphibian conservation since management efforts are not typically concerned with naturally occurring ubiquitous threats such as those from small invertebrate predators, as it is rarely been observed in nature. However, this may be perhaps due their ability to consume prey rapidly, especially if working in packs. Although amphibian conservation plans always expect some losses from natural predation, diving beetles may seriously affect conservation efforts such as captive breeding and reintroductions with populations already on the threshold of extinction and where every individual critical to success.

Predaceous Diving Beetles (Coleoptera: Dytiscidae) May Affect the Success of Amphibian Conservation Efforts

During weekly monitoring of a compensatory habitat reintroduction for an endangered frog species, a group of a dozen adult diving beetles (Coleoptera: Dytiscidae) were encountered attacking and quickly dismembering and consuming a tadpole. A single adult diving beetle was also discovered burrowing its head deep inside and consuming a tadpole approximately three to four times its size. Although Dytiscidae are known to occasionally consume vertebrates such as tadpoles, adults are typically considered scavengers, and this communal predatory behavior and feeding method have not been previously documented. Besides these interesting novel behaviors, these observations may have implications for amphibian conservation since management efforts are not typically concerned with naturally occurring ubiquitous threats such as those from small invertebrate predators, as it is rarely been observed in nature. However, this may be perhaps due their ability to consume prey rapidly, especially if working in packs. Although amphibian conservation plans always expect some losses from natural predation, diving beetles may seriously affect conservation efforts such as captive breeding and reintroductions with populations already on the threshold of extinction and where every individual critical to success.