Nesting in close quarters: Causes and benefits of high-density nesting behaviour in Painted Turtles

Many oviparous reptiles nest in aggregations and with temporal synchrony. We hypothesized that these traits reflect attraction by conspecifics rather than limiting suitable habitat. We quantified whether Painted Turtles (Chrysemys picta (Schneider, 1783)) in Algonquin Park, Ontario, were nesting communally, identified cues females used to select nest sites, and tested whether hatching success was higher in spatially-clustered nests. We found that nests were closer to one another than expected by chance (i.e., were clustered), but that individual nest site selection was only weakly influenced by micro-habitat characteristics. Survival of clustered nests (49%) was not significantly higher than that of solitary nests (39%). When turtle models were placed on the nesting embankment, females nested most often with the highest density of models. Given that reproductive lifespan is the major axis of fitness and that there was little benefit to nest survival in clustered nests, we suggest that clustering is related to females cueing to conspecific nests to expedite the nesting process and gain a good-quality nest site (chosen by the first nesting female in the cluster) while investing little energy in nest-site selection. This strategy may reduce time spent on land, thereby minimizing chances of dehydration, temperature stress, and adult depredation.

Host Plant Availability and Nest-Site Selection of the Social Spider Stegodyphus dumicola Pocock, 1898 (Eresidae)

An animals’ habitat defines the resources that are available for its use, such as host plants or food sources, and the use of these resources are critical for optimizing fitness. Spiders are abundant in all terrestrial habitats and are often associated with vegetation, which may provide structure for anchoring capture webs, attract insect prey, or provide protective function. Social spiders construct sedentary communal silk nests on host plants, but we know little about whether and how they make nest-site decisions. We examined host plant use in relation to host plant availability in the social spider Stegodyphus dumicola Pocock, 1898 (Eresidae) across different arid biomes in Namibia and analysed the role of host plant characteristics (height, spines, scent, sturdiness) on nest occurrence. Host plant communities and densities differed between locations. Spider nests were relatively more abundant on Acacia spp., Boscia foetida, Combretum spp., Dichrostachys cinerea, Parkinsonia africana, Tarchonanthus camphoratus, and Ziziphus mucronatus, and nests survived longer on preferred plant genera Acacia, Boscia and Combretum. Spider nests were relatively more abundant on plants higher than 2 m, and on plants with thorns and with a rigid structure. Our results suggest that spiders display differential use of host plant species, and that characteristics such as rigidity and thorns confer benefits such as protection from browsing animals.

Population density, habitat preference, and breeding biology of Chukar Partridge (Alectoris chukar) in Malakand division, Khyber Pakhtunkhwa, Pakistan

The field biology of Chukar Partridge (Alectoris chukar) was studied in Malakand division, which is an important range of its distribution in Pakistan. The abundance of the species at different altitudes was studied using both transect trails of various lengths and point counts at certain spots. The average monthly population density was estimated to be 1.448±0.466 birds/ha. The population density in August, September, and October 2020 was significantly (P<0.05) higher, as compared to the rest of the months. Chukar Partridge sightings were the lowest in December, with mean±SD = 0.996±0.147 birds/ha and the highest in October 2.333±0.202 birds/ hae in all the study sites. At each study site, maximum activity habitats were marked and selected for breeding ecology study. Data was collected on breeding time, nest site selection, nest size, incubation period, and hatching success. The breeding season in this species starts in February, with the peak months being March and April, when calls are frequently heard. The frequency of calls varied from 0.15 to 0.3 per minute. Throughout the breeding season, twelve nests were observed using binoculars and camera traps from a distance to avoid disturbance, wherever possible and without disrupting the species. Nesting sites were mostly on slopes under the eaves of Dodonea viscosa, Calotropis procera and Zizyphus oxyphylla. Dry leaves of Poa annua, Cynodon dactylon, Dichanthium annulatum, small twigs of bushes, and downy feathers were used as nesting materials. The average diameter of nest (n=12) was 25.43±3.4 (mean±SD) cm. Overall, the mean clutch size was 94.5±30.187 egg/nest with an incubation period of 22–24 days. The hatching success rate was 82% with 315 successfully hatched chicks, while the fledging rate was 83% (265 fledged out of 315 hatched in, n=42 nests).

Ecology, Taxonomic Status, and Conservation of the South Georgian Diving Petrel (Pelecanoides georgicus) in New Zealand

<p>Procellariiformes is a diverse order of seabirds under considerable pressure from onshore and offshore threats. New Zealand hosts a large and diverse community of Procellariiformes, but many species are at risk of extinction. In this thesis, I aim to provide an overview of threats and conservation actions of New Zealand’s Procellariiformes in general, and an assessment of the remaining terrestrial threats to the South Georgian Diving Petrel (Pelecanoides georgicus; SGDP), a Nationally Critical Procellariiform species restricted to Codfish Island (Whenua Hou), post invasive species eradication efforts in particular. I reviewed 145 references and assessed 14 current threats and 13 conservation actions of New Zealand’s Procellariiformes (n = 48) in a meta-analysis. I then assessed the terrestrial threats to the SGDP by analysing the influence of five physical, three competition, and three plant variables on nest-site selection using an information theoretic approach. Furthermore, I assessed the impacts of interspecific interactions at 20 SGDP burrows using remote cameras. Finally, to address species limits within the SGDP complex, I measured phenotypic differences (10 biometric and eight plumage characters) in 80 live birds and 53 study skins, as conservation prioritisation relies on accurate taxonomic classification. The results from the meta-analysis revealed that New Zealand’s Procellariiformes are at risk from various threats (x̅= 5.50 ± 0.34), but species also receive aid from several conservation actions (x̅= 7.19 ± 0.33). Results from a logistic regression showed that smaller species are more threatened onshore than offshore. The majority of the conservation actions appear in place where needed. However, habitat management, native predator control and the mitigation of risks associated with environmental stochasticity may need improvement. Analysis of SGDP nest-site selection showed dependency on mobile, steep, seaward-facing foredunes. Invasive plant species, the presence of conspecifics, or the presence of other seabird species did not influence SGDP nest-site selection. Assessment of interspecific interactions at SGDP burrows showed seven species occurring at burrows, but only Common Diving Petrels (P. urinatrix; CDP) interfered with SGDP breeding success. Assessment of phenotypic differences within the SGDP revealed that the New Zealand SGDP population differs in five biometric and three plumage characters from all other populations and warrants species status based on a species delimitation test with quantitative criteria. I propose to name this Critically Endangered species Pelecanoides taylorii sp. nov. These findings indicate that P. taylorii is of considerable conservation concern and additional measures, even after successful eradication of invasive species, may be required to safeguard this species. Based on the habitat preference, stochastic events, such as storms and storm surges, appear a major threat to P. taylorii. The assessed interspecific interactions at nest-sites, indicate competition with CDPs to be a minor threat. I propose a translocation as a potential strategy to relieve the pressure on P. taylorii, but further monitoring and research is needed to enable the implementation of such a conservation strategy.</p>

Ecology, Taxonomic Status, and Conservation of the South Georgian Diving Petrel (Pelecanoides georgicus) in New Zealand

<p>Procellariiformes is a diverse order of seabirds under considerable pressure from onshore and offshore threats. New Zealand hosts a large and diverse community of Procellariiformes, but many species are at risk of extinction. In this thesis, I aim to provide an overview of threats and conservation actions of New Zealand’s Procellariiformes in general, and an assessment of the remaining terrestrial threats to the South Georgian Diving Petrel (Pelecanoides georgicus; SGDP), a Nationally Critical Procellariiform species restricted to Codfish Island (Whenua Hou), post invasive species eradication efforts in particular. I reviewed 145 references and assessed 14 current threats and 13 conservation actions of New Zealand’s Procellariiformes (n = 48) in a meta-analysis. I then assessed the terrestrial threats to the SGDP by analysing the influence of five physical, three competition, and three plant variables on nest-site selection using an information theoretic approach. Furthermore, I assessed the impacts of interspecific interactions at 20 SGDP burrows using remote cameras. Finally, to address species limits within the SGDP complex, I measured phenotypic differences (10 biometric and eight plumage characters) in 80 live birds and 53 study skins, as conservation prioritisation relies on accurate taxonomic classification. The results from the meta-analysis revealed that New Zealand’s Procellariiformes are at risk from various threats (x̅= 5.50 ± 0.34), but species also receive aid from several conservation actions (x̅= 7.19 ± 0.33). Results from a logistic regression showed that smaller species are more threatened onshore than offshore. The majority of the conservation actions appear in place where needed. However, habitat management, native predator control and the mitigation of risks associated with environmental stochasticity may need improvement. Analysis of SGDP nest-site selection showed dependency on mobile, steep, seaward-facing foredunes. Invasive plant species, the presence of conspecifics, or the presence of other seabird species did not influence SGDP nest-site selection. Assessment of interspecific interactions at SGDP burrows showed seven species occurring at burrows, but only Common Diving Petrels (P. urinatrix; CDP) interfered with SGDP breeding success. Assessment of phenotypic differences within the SGDP revealed that the New Zealand SGDP population differs in five biometric and three plumage characters from all other populations and warrants species status based on a species delimitation test with quantitative criteria. I propose to name this Critically Endangered species Pelecanoides taylorii sp. nov. These findings indicate that P. taylorii is of considerable conservation concern and additional measures, even after successful eradication of invasive species, may be required to safeguard this species. Based on the habitat preference, stochastic events, such as storms and storm surges, appear a major threat to P. taylorii. The assessed interspecific interactions at nest-sites, indicate competition with CDPs to be a minor threat. I propose a translocation as a potential strategy to relieve the pressure on P. taylorii, but further monitoring and research is needed to enable the implementation of such a conservation strategy.</p>

Nest-site selection and nest design of Iberian bullfinches Pyrrhula pyrrhula iberiae in northwestern Spain

Nest-habitat selection and nest design in a Eurasian bullfinch population in the Iberian Peninsula are thoroughly addressed in this study for the first time. Hedgerows and meadows were found around all of the nests and most of them were supported by hedgerows, so bullfinches consistently used the general woody vegetation available as reproduction habitat and site. Also, poplar plantations appeared preferentially in the immediate surroundings of the nests. Partly reflecting these results, bullfinches chose zones with greater shrub and tree cover than that available. Bullfinches placed their nests on a wide variety of plant species, but showed predilection for thorny species. Overall mean height of nests above the ground was 1.43 m and large-sized shrubs/trees were preferred. The most predominant bullfinch nest orientations were S, E and centered, which arguably provided thermal benefits and protected from severe weather. In general, there were no significant temporal variations in nest-site selection. With the exception of thorny support and favourable orientation, acting jointly, there was no significant association between nest-site characteristics and nesting success, presumably because many nests were already located in the most advantageous places at each time, and because despite this, predation pressure was high. Nest external dimensions were relatively variable, whereas internal width was the least variable nest dimension. No significant monthly or interannual variations in nest weight were observed. Larger nests did not hold larger clutches. Successful nests were larger than unsuccessful ones. The bullfinch nests were of simple construction, with two clearly different regions, the outer nest and the internal cup, with no significant temporal variations in the weight of either. The outer, structural nest consisted mainly of twigs, whereas roots and herbaceous shoots were the highest fractions lining the cup. Hair was the only animal-derived material used by bullfinches.