Investigating the effects of predator removal and habitat management on nest success and breeding population size of a farmland passerine: a case study

SummaryA survey of Scottish Crossbills Loxia scotica was carried out in 3,506 km2 of conifer woodland in northern Scotland during January to April 2008 to provide the first estimate of the global population size for this endemic bird. Population estimates were also made for Common Crossbills L. curvirostra and Parrot Crossbills L. pytyopsittacus within this range. Crossbills were lured to systematically selected survey points for counting, sexing and recording their calls for later call-type (species) identification from sonograms. Crossbills were located at 451 of the 852 survey points, and adequate tape-recordings made at 387 of these. The Scottish Crossbill had a disjunct distribution, occurring largely within the eastern part of the study area, but also in the northwest. Common Crossbills had a mainly westerly distribution. The population size of post-juvenile Scottish Crossbills was estimated as 13,600 (95% C.I. 8,130–22,700), which will approximate to 6,800 (4,065–11,350) pairs. Common Crossbills were more abundant within this range (27,100, 95% C.I. 14,700–38,400) and Parrot Crossbills rare (about 100). The sex ratio was not significantly different from parity for Scottish Crossbills. The modal number at survey points was two but numbers were larger in January than later in the survey. The numbers and distribution of all crossbill species are likely to vary between years, depending upon the size of the cone crops of the different conifers: all were coning in 2008. Common Crossbill and Parrot Crossbill numbers will also be affected by irruptions from continental Europe. A monitoring scheme is required to detect any population trend, and further work on their habitat requirement (e.g. conifer selection at different seasons) is needed to inform habitat management of native and planted conifer forests to ensure a secure future for this endemic bird.

Download Full-text

Fish Habitat: Essential Fish Habitat and Rehabilitation

Fish Habitat: Essential Fish Habitat and Rehabilitation ◽

10.47886/9781888569124.ch27 ◽

1999 ◽

Keyword(s):

Lake Erie ◽

Habitat Management ◽

Fish Habitat ◽

Learning By Doing ◽

Suitable Habitat ◽

Physical Habitat ◽

Fish Stocks ◽

Habitat Features ◽

Fish Habitats

<em>Abstract.—</em> The quality and quantity of habitats determine ecosystem productivity. Hence, they determine the potential fish productivity that sustains the fish harvests extractable from freshwaters and seas. Efforts to conserve and protect fish habitats are frustrated by key unanswered questions: which habitat types and how much must be protected to ensure natural self-sustaining fish stocks? Minns and Bakelaar presented a prototype method for assessing suitable habitat supply for fish stocks in Lake Erie, an analysis that can be used to address conservation issues. Here, the method is refined and extended, taking the assessment of habitat supply for pike <em>Esox lucius </em> in the Long Point region of Lake Erie as a case study. As with the previous study, much emphasis is placed on “learning by doing.” Because available inventories of habitat features are coarse and incomplete, improved guidelines for estimating habitat supply are expected from these prototype studies. The habitat supply method previously presented by Minns and Bakelaar is elaborated in three ways here: (1) the basic physical habitat assessment is derived from a remote-sensing inventory database; (2) methods of quantifying the thermal regime and integrating it with other habitat elements are examined; (3) habitat supply estimates are used in a pike population model, and pike biomass and production are simulated for the Long Point region of Lake Erie and then compared with available records. The roles of error and uncertainty are examined for all elements in the estimation and application of suitable habitat supply values. There is potential for supply measurement and analysis to guide fish habitat management.

Download Full-text

Predator exclosures, predator removal, and habitat improvement increase nest success of Snowy Plovers in Oregon, USA

The Condor ◽

10.1650/condor-14-7.1 ◽

2014 ◽

Vol 116 (4) ◽

pp. 619-628 ◽

Cited By ~ 8

Author(s):

Stephen J. Dinsmore ◽

David J. Lauten ◽

Kathleen A. Castelein ◽

Eleanor P. Gaines ◽

Mark A. Stern

Keyword(s):

Nest Success ◽

Predator Removal ◽

Habitat Improvement ◽

Snowy Plovers

Download Full-text

Estimating western ringtail possum (Pseudocheirus occidentalis) density using distance sampling

Australian Mammalogy ◽

10.1071/am09037 ◽

2010 ◽

Vol 32 (2) ◽

pp. 197 ◽

Cited By ~ 1

Author(s):

G. R. Finlayson ◽

A. N. Diment ◽

P. Mitrovski ◽

G. G. Thompson ◽

S. A. Thompson

Keyword(s):

Urban Development ◽

Population Size ◽

Western Australia ◽

Distance Sampling ◽

Reliable Estimate ◽

Population Estimates ◽

Density Estimates ◽

The Subject ◽

Ringtail Possum

A reliable estimate of population size is of paramount importance for making management decisions on species of conservation significance that may be impacted during development. The western ringtail possum (Pseudocheirus occidentalis) is regularly encountered during urban development and is the subject of numerous surveys to estimate its abundance. A variety of techniques have been used for this species with mixed results. This paper reports on a case study using distance sampling to estimate density of P. occidentalis in a small habitat remnant near Busselton, Western Australia. Density estimates obtained were within the range of previous studies of this species and we suggest that this technique should be employed in future surveys to improve the accuracy of population estimates for this species before development.

Download Full-text

A Study of Population Size and Activity Patterns and Their Relationship to the Prey Species of the Eurasian Lynx Using a Camera Trapping Approach

Animals ◽

10.3390/ani9110864 ◽

2019 ◽

Vol 9 (11) ◽

pp. 864

Author(s):

Xiaoming Tang ◽

Shupei Tang ◽

Xiaoyu Li ◽

Dalai Menghe ◽

Wuliji Bao ◽

...

Keyword(s):

Community Structure ◽

Population Size ◽

Habitat Management ◽

Activity Patterns ◽

Management Strategies ◽

Camera Trapping ◽

Ecosystem Functions ◽

Lynx Lynx ◽

Eurasian Lynx ◽

Different Seasons

Revealing the behavioral relationships between predators and their prey is fundamental in understanding the community structure and ecosystem functions of such animals. This study aimed at detecting the population size and activity patterns of Eurasian lynx (Lynx lynx) (along with its prey) by camera trapping monitoring from 2014 to 2017 at the Saihanwula nature reserve in central Inner Mongolia. The total effective trapping days were 29,892 and 20 lynx were identified from 343 trapping photos based on the inner side patterns of their forelimbs. The daily activity rhythms of the lynx overlapped with those of different prey in different seasons. The yearly activity pattern of the lynx was influenced by its main prey’s biology. In conclusion, this study reveals that the activity patterns of the top predator matched those of its prey in different time periods. Habitat management strategies promoting the restoration of prey communities would benefit the lynx in maintaining a stable community structure.

Download Full-text

Fish population size, and not density, as the determining factor of parasite infection: a case study

Parasitology ◽

10.1017/s0031182003004566 ◽

2004 ◽

Vol 128 (3) ◽

pp. 305-313 ◽

Cited By ~ 58

Author(s):

A. M. BAGGE ◽

R. POULIN ◽

E. T. VALTONEN

Keyword(s):

Species Richness ◽

Population Density ◽

Population Size ◽

Fish Population ◽

Host Population ◽

Fish Length ◽

Total Fish ◽

Infection Parameters ◽

The Mean

The diversity and abundance of parasites vary widely among populations of the same host species. These infection parameters are, to some extent, determined by characteristics of the host population or of its habitat. Recent studies have supported predictions derived from epidemiological models regarding the influence of host population density: parasite abundance and parasite species richness are expected to increase with increasing host population density, at least for directly transmitted parasites. Here, we test this prediction using a natural system in which populations of the crucian carp, Carassius carassius (L.), occur alone, with no other fish species, in a series of 9 isolated ponds in Finland. The ectoparasite communities in these fish populations consist of only 4 species of monogeneans (Dactylogyrus formosus, D. wegeneri, D. intermedius and Gyrodactylus carassii); the total and relative abundance of these 4 species varies among ponds, with one or two of the species missing from certain ponds. Across ponds, only one factor, total fish population size, explained a significant portion of the variance in both the mean number of monogenean species per fish and the mean total abundance of monogenean individual per fish. In contrast, fish population density did not influence either monogenean abundance or species richness, and neither did any of the other variables investigated (mean fish length per pond, number of fish examined per pond, distance to the nearest lake, and several water quality measures). In our system, proximity among fish individuals (i.e. host population density) may not be relevant to the proliferation of monogeneans; instead, the overall availability of host individuals in the host population appeared to be the main constraint limiting parasite population growth.

Download Full-text