Landscape-wide pulse events predict trait-based responses among wetland birds in perennial channels of a dryland wetland.

Wetlands in arid or semiarid zones are vital for maintaining biodiversity but face growing threats. Flooding regime variability is a key driver of ecological dynamism in these systems, dictating primary productivity on a large spatial scale. The functional composition or diversity of wetland-dependent bird species has been found to be sensitive to fluctuations in hydrological regimes and can thus be indicative of cascading ecosystem responses associated with climate change. In this paper, we investigate whether large-scale changes in inundation and fire-a significant additional biodiversity determinant in (semi-)arid landscapes-are reliable predictors of functional group responses of wetland-dependent birds along a perennial channel of the Okavango Delta, Botswana. We fit generalized additive models (GAMs) to 6 years of bird survey data collected along ~190-km-long annual transects and use remotely sensed landscape-level inundation estimates, as well as spatiotemporal distance to fire, to predict the responsiveness of seven trait-based functional group abundances. During the surveys, a total of 89 different wetland-dependent bird species were recorded, including 76 residents, across all years, with below-surface feeding waders consistently the most abundant functional group. Including estimated spatiotemporal variability in flooding and fire, as well as their interactions, improved model fit for all seven functional groups, explaining between 46.8% and 68.3% of variability in functional group abundances. Covariates representing longer-term variability in inundation generally performed better than shorter-term ones. For example, variability in inundation over the 5 months preceding a survey best predicted the responses of all functional groups, which also all exhibited responsiveness to the interaction between flooding and fire. We were able to interpret the responses of individual functional groups, based on the resource exploitation assumption. Overall, our results suggest that perennial waters in dryland wetlands offer functional refugia to wetland-dependent birds and highlight the indicative power of large-scale trait-based bird monitoring. Our findings demonstrate the potential utility of such a monitoring regime for dryland wetland ecosystems vulnerable to industrial-scale anthropogenic pressure and associated climate change.

Beak and feather disease viruses circulating in Cape parrots (Poicepahlus robustus) in South Africa.

Captive and wild psittacines are vulnerable to the highly contagious psittacine beak and feather disease. The causative agent, beak and feather disease virus (BFDV), was recently detected in the largest remaining population of endangered Cape parrots (Poicepahlus robustus), which are endemic to South Africa. Full-length genomes were isolated and sequenced from 26 blood samples collected from wild and captive Cape parrots to determine possible origins of infection. All sequences had characteristic BFDV sequence motifs and were similar in length to those described in the literature. However, BFDV coat protein (CP) sequences from this study did not contain a previously identified bipartite nuclear localisation signal (NLS) within residues 39-56, which indicates that an alternate NLS is involved in shuttling the CP into the nucleus. Sequences from the wild population shared a high degree of similarity, irrespective of year or location, suggesting that the disease outbreak occurred close to the time when the samples were collected. Phylogenetic analysis of full-length genomes showed that the captive Cape parrot sequences cluster with those isolated from captive-bred budgerigars in KwaZulu-Natal Province, South Africa. Exposure to captive-bred Cape parrots from a breeding facility in KwaZulu-Natal is suggested as a possible source for the virus infection. Phylogenetic analysis of BFDV isolates from wild and captive Cape parrots indicated two separate infection events in different populations, which highlights the potential risk of introducing new strains of the virus into the wild population. The present study represents the first systematic investigation of BFDV virus diversity in the southern-most population of Cape parrots.

Beak and feather disease virus: correlation between viral load and clinical signs in wild Cape parrots (Poicepahlus robustus) in South Africa.

Psittacine beak and feather disease (PBFD), the most prevalent viral disease affecting psittacines, is caused by beak and feather disease virus (BFDV). This study assessed viral load using qPCR in a wild Cape parrot population affected by PBFD and compared it to overall physical condition based on clinical signs attributable to PBFD. A significant inverse correlation between viral load and overall physical condition was found, which confirmed that clinical signs may confidently be used to diagnose the relative severity of BFDV infections in wild populations. This is the first assessment of BFDV viral load in a wild psittacine population.

Recovery from Beak and Feather Disease Virus Infection in a Cape Parrot (Poicephalus robustus) Population in South Africa.

Psittacine beak and feather disease (PBFD) is one of the most important viral diseases affecting parrot species worldwide. Outbreaks of PBFD have been reported in wild endemic and endangered South African Cape Parrots (Poicephalus robustus), most recently in 2008. A previous study of wild Cape Parrots in the Eastern Cape region of South Africa in 2010-11 found 34/49 birds positive for beak and feather disease virus (BFDV), the causative agent of PBFD, showing that the outbreak was still ongoing. The present study (2015-16) screened 30 blood samples from the same Cape Parrot population for BFDV infection by PCR: all parrots were found to be BFDV DNA-negative, which showed both that BFDV infection in the region has declined and that the parrot population has recovered. Our data contribute to the important negative data set which permits monitoring the progress of BFDV infections in wild Psittaciformes. We recommend a PCR method with universal BFDV primers as a quick, easy, and consistent diagnostic test for BFDV detection.