Nancy Jennings - Academia.edu (original) (raw)
Papers by Nancy Jennings
Wildlife Biology, 2017
The European brown hare Lepus europaeus is an r‐selected species showing relatively high fecundit... more The European brown hare Lepus europaeus is an r‐selected species showing relatively high fecundity, and changes in the hare population can be influenced by the timing of hunting and reproductive activity. Between February and August in Europe, the majority of female hares are either pregnant or suckling young, or both, and if a female is killed during the suckling period, the young hares (leverets) are orphaned and are likely to die of starvation. In England and Wales, in contrast with other European countries, there is no close season when hunting hares is prohibited, and the peak time of hunting in February coincides with the start of reproductive activity. We explore the impact of hunting practices on the risk of death by starvation of dependent young. By modelling scenarios of hunting at the highest documented rate at times of the year based on practices adopted in England and Wales, and by comparing this with the close season practice in Scotland, we quantify seasonally variabl...
Journal of Applied Ecology, 2005
Summary Questionnaires, or social surveys, are used increasingly as a means of collecting data in... more Summary Questionnaires, or social surveys, are used increasingly as a means of collecting data in ecology. We present a critical review of their use and give recommendations for good practice. We searched for papers in which questionnaires were used in 57 ecological academic journals, published over the period 1991–2003 inclusive. This provided a total sample size of 168 questionnaires from 127 papers published in 22 academic journals. Most questionnaires were carried out in North America and western Europe, and addressed species‐level issues, principally focusing on mammals. The majority were concerned with impacts of species and/or their conservation, and just under half with human–wildlife interactions. Postal survey was the method used most frequently to carry out the questionnaires, followed by in‐person interviews. Some questionnaires were conducted by telephone, and none was web‐based. Most questionnaires were concerned with obtaining factual information or perceptions of fac...
Zoo Biology, 2000
The daily food consumption of 26 California sea lions at the Harderwijk Marine Mammal Park was re... more The daily food consumption of 26 California sea lions at the Harderwijk Marine Mammal Park was recorded. Average annual food consumption of males increased with age to stabilize at approximately 4,000 kg/year by the age of 10 years. Females showed a rapid increase in average annual food consumption until they were 3 years old. Thereafter, females housed outdoors averaged 1,800 kg/year, whereas those housed indoors ate approximately 1,400 kg/year. Between the ages of 4 and 7 years, the food intake of males began to fluctuate seasonally, decreasing between May and August. The low food intake in summer was associated with an increase in aggressive behavior. Seasonal fluctuation in the food intake of non-reproductive females was negligible. Between the ages of 6 and 8 years, many females began to reproduce successfully. Pups were born in May and June. The females' food intake decreased approximately 3 days before birth and ceased the next day. Feeding resumed the day after birth, and by 2 days after birth, it had usually returned to normal. On average, female intake increased in the year of conception, the year of birth, during which the pup was suckled for 6 months, and the following calendar year, during which the pup was weaned. Pups began to eat fish at approximately 11 months of age. When forcefed, they were fully weaned within 2 to 23 days. Male weight and body length increased until approximately 20 years of age. Females increased in body length until 6 years and in weight until approximately 13 years of age. The relationship between standard body length and body weight is given. The heavier an animal is, the lower is its food intake as a percentage of body weight. Zoo Biol 19:143-159, 2000.
Marine Environmental Research, 2017
All rights reserved. No part of this publication may be reproduced and/or published by print, pho... more All rights reserved. No part of this publication may be reproduced and/or published by print, photoprint, microfilm or any other means, without the previous written consent of SEAMARCO. In case this report was drafted on instructions, the rights and obligations of contracting parties are subject to the relevant agreement concluded between the contracting parties. © 2016 SEAMARCO Effect pile driving sound on sea bass Kastelein et al.
Zoo Biology, 2007
In the wild, walrus calves are occupied with many behaviors necessary for survival. In captivity ... more In the wild, walrus calves are occupied with many behaviors necessary for survival. In captivity there is usually less to occupy them. Therefore it is necessary to develop other ways to occupy the animals to prevent negative behavior. In the present study, food in four different types of dispensers were tested on two walrus calves: fish in ice, fish in a nine‐hole container, fish in a two‐hole container, and fish in ice in a one‐hole container. All four methods of offering fish had an effect on the animals' behavior. There were differences in the way the two animals responded to each of the four dispensers. The dispensers occupied one animal on average between 32–95% of the 90‐min test periods, and the other animal for between 14–57% of the test periods. Due to the effect of learning and rapid development of the calves, which were shifting from a 100% formula diet to a 100% fish diet during the study period, the four methods cannot be compared. Besides the time feeding methods o...
Marine Mammal Science, 2000
In an attempt to test the effectiveness of sounds in deterring harbor porpoises from nets and red... more In an attempt to test the effectiveness of sounds in deterring harbor porpoises from nets and reducing porpoise bycatch in gill net fisheries, two harbor porpoises, kept in a large floating pen at Neeltje Jans, The Netherlands, were subjected to 3 different underwater sounds. The effect of each sound was judged by comparing the animals' behavior during a 15‐min test period with that during a 15‐min baseline period immediately before the test and a 15‐min recovery period immediately after the test. The effects of the alarms were quantified as the distance between the porpoises' surfacings and the alarm and the animals' respiration rates. Each alarm was tested in two positions in the pen. The behavior observed was related to the sound‐pressure‐level distribution in the pen. All three alarms: the standard Dukane alarm (a commercially available alarm with a regular pulse interval of 4.3 sec used to deter dolphins from fishing nets), the random Dukane alarm (the same alarm wi...
Marine Environmental Research, 2008
Two harbor porpoises in a floating pen were subjected to five pure tone underwater signals of 70 ... more Two harbor porpoises in a floating pen were subjected to five pure tone underwater signals of 70 or 120 kHz with different signal durations, amplitudes and duty cycles (% of time sound is produced). Some signals were continuous, others were intermittent (duty cycles varied between 8-100 %). The effect of each signal was judged by comparing the animals' surfacing locations and number of surfacings (i.e. number of respirations) during test periods with those during baseline periods. In all cases, both porpoises moved away from the sound source, but the effect of the signals on respiration rates was negligible. Pulsed 70 kHz signals with a Source Level (SL) of 137 dB had a similar effect to a continuous 70 kHz signal with a SL of 148 dB (re 1 Pa, rms). However, a pulsed 70 kHz signal with a SL of 147 dB had a much stronger deterring effect than a continuous 70 kHz signal with a similar SL. For pulsed 70 kHz signals (2 s pulse duration, 4 s pulse interval, SL 147 dB re 1 Pa, rms), the avoidance threshold Sound Pressure Level (SPL), in the context of the present study, was estimated to be around 130 dB (re 1µPa, rms) for porpoise 064 and around 124 dB (re 1µPa, rms) for porpoise 047. This study shows that ultrasonic pingers (70 kHz) can deter harbor porpoises. Such ultrasonic pingers have the advantage that they do not have a "dinner bell" effect on pinnipeds, and probably have no, or less, effect on other marine fauna, which are often sensitive to low frequency sounds.
Marine Environmental Research, 2007
Worldwide many cetaceans drown incidentally in fishing nets. To reduce the unwanted bycatch in gi... more Worldwide many cetaceans drown incidentally in fishing nets. To reduce the unwanted bycatch in gillnets, pingers (acoustic alarms) have been developed that are attached to the nets. In the European Union, pingers will be made compulsory in some areas in 2005 and in others in 2007. However, pingers may effect non-target marine fauna such as fish. Therefore in this study, the effects of seven presently commercially-available pingers on the behaviour of five North Sea fish species in a large tank were quantified. The species tested were: sea bass (Dicentrarchus labrax), pout (Trisopterus luscus), thicklip mullet (Chelon labrosus), herring (Clupea harengus), and cod (Gadus morhua). The fish were housed as single-species schools of 9-13 individuals in a tank. The behaviour of fish in quiet periods was compared with their behaviour during periods with active pingers. The results varied both between pingers and between fish species. Sea bass decreased their speed in response to one pinger and swam closer to the surface in response to another. Thicklip mullet swam closer to the bottom in response to two pingers and increased their swimming speed in response to one pinger. Herring swam faster in response to one pinger, and pout and cod (close relatives) showed no behavioural responses to any of the pingers. Of the seven pingers tested, four elicited responses in at least one fish species, and three elicited no responses. Whether similar responses would be elicited in these fish species in the wild, and if so, whether such responses would influence the catch rate of fisheries, cannot be derived from the results of this study. However, the results indicate the need for field studies with pingers and fish. Based on the small number of fish species tested, the present study suggests that the higher the frequency of a pinger, the less likely it is to affect the behaviour of marine fish.
Marine Environmental Research, 2008
Mammal Review, 2006
Accurate and sensitive survey and monitoring methods are needed for shrews. We present a new desi... more Accurate and sensitive survey and monitoring methods are needed for shrews. We present a new design of hair tube and a new, simple method of species identification from multivariate analysis of four parameters measured from shrew guard hairs using a binocular microscope with incident light. Multivariate analysis of these parameters measured from hairs of known identity showed that they can be used to identify hair to the species level with 85% accuracy. We compared our indices of abundance from hair tubes (the hair tube index) with those from live trapping in 40 field margins. Capture‐mark‐recapture methods showed that capture rate did not vary systematically across sites, so that number of individuals captured was used as an index of abundance. The hair tube index showed a significant association with the number of individuals captured for Sorex araneus and Neomys fodiens. The lack of a significant association for Sorex minutus may be because hair tubes are more sensitive in detect...
The Journal of the Acoustical Society of America, 2008
Echolocation effort (number and duration of echolocation click trains produced) by a harbor porpo... more Echolocation effort (number and duration of echolocation click trains produced) by a harbor porpoise is described in relation to target presence, strength and distance, and performance of the detection task. The porpoise was presented with two target sizes at five distances (12–20m), or no target, and had to indicate whether it could detect the target. Small, distant targets required long and multiple click trains. Multiple click trains mostly occurred when the small target was far away and not detected, and during target-absent trials in which the animal correctly responded. In target-absent trials, an incorrect response was linked to short click trains. Click train duration probably increased until the animal’s certainty about the target’s presence or absence exceeded a certain level, after which the porpoise responded.
Wildlife Biology, 2017
The European brown hare Lepus europaeus is an r‐selected species showing relatively high fecundit... more The European brown hare Lepus europaeus is an r‐selected species showing relatively high fecundity, and changes in the hare population can be influenced by the timing of hunting and reproductive activity. Between February and August in Europe, the majority of female hares are either pregnant or suckling young, or both, and if a female is killed during the suckling period, the young hares (leverets) are orphaned and are likely to die of starvation. In England and Wales, in contrast with other European countries, there is no close season when hunting hares is prohibited, and the peak time of hunting in February coincides with the start of reproductive activity. We explore the impact of hunting practices on the risk of death by starvation of dependent young. By modelling scenarios of hunting at the highest documented rate at times of the year based on practices adopted in England and Wales, and by comparing this with the close season practice in Scotland, we quantify seasonally variabl...
Journal of Applied Ecology, 2005
Summary Questionnaires, or social surveys, are used increasingly as a means of collecting data in... more Summary Questionnaires, or social surveys, are used increasingly as a means of collecting data in ecology. We present a critical review of their use and give recommendations for good practice. We searched for papers in which questionnaires were used in 57 ecological academic journals, published over the period 1991–2003 inclusive. This provided a total sample size of 168 questionnaires from 127 papers published in 22 academic journals. Most questionnaires were carried out in North America and western Europe, and addressed species‐level issues, principally focusing on mammals. The majority were concerned with impacts of species and/or their conservation, and just under half with human–wildlife interactions. Postal survey was the method used most frequently to carry out the questionnaires, followed by in‐person interviews. Some questionnaires were conducted by telephone, and none was web‐based. Most questionnaires were concerned with obtaining factual information or perceptions of fac...
Zoo Biology, 2000
The daily food consumption of 26 California sea lions at the Harderwijk Marine Mammal Park was re... more The daily food consumption of 26 California sea lions at the Harderwijk Marine Mammal Park was recorded. Average annual food consumption of males increased with age to stabilize at approximately 4,000 kg/year by the age of 10 years. Females showed a rapid increase in average annual food consumption until they were 3 years old. Thereafter, females housed outdoors averaged 1,800 kg/year, whereas those housed indoors ate approximately 1,400 kg/year. Between the ages of 4 and 7 years, the food intake of males began to fluctuate seasonally, decreasing between May and August. The low food intake in summer was associated with an increase in aggressive behavior. Seasonal fluctuation in the food intake of non-reproductive females was negligible. Between the ages of 6 and 8 years, many females began to reproduce successfully. Pups were born in May and June. The females' food intake decreased approximately 3 days before birth and ceased the next day. Feeding resumed the day after birth, and by 2 days after birth, it had usually returned to normal. On average, female intake increased in the year of conception, the year of birth, during which the pup was suckled for 6 months, and the following calendar year, during which the pup was weaned. Pups began to eat fish at approximately 11 months of age. When forcefed, they were fully weaned within 2 to 23 days. Male weight and body length increased until approximately 20 years of age. Females increased in body length until 6 years and in weight until approximately 13 years of age. The relationship between standard body length and body weight is given. The heavier an animal is, the lower is its food intake as a percentage of body weight. Zoo Biol 19:143-159, 2000.
Marine Environmental Research, 2017
All rights reserved. No part of this publication may be reproduced and/or published by print, pho... more All rights reserved. No part of this publication may be reproduced and/or published by print, photoprint, microfilm or any other means, without the previous written consent of SEAMARCO. In case this report was drafted on instructions, the rights and obligations of contracting parties are subject to the relevant agreement concluded between the contracting parties. © 2016 SEAMARCO Effect pile driving sound on sea bass Kastelein et al.
Zoo Biology, 2007
In the wild, walrus calves are occupied with many behaviors necessary for survival. In captivity ... more In the wild, walrus calves are occupied with many behaviors necessary for survival. In captivity there is usually less to occupy them. Therefore it is necessary to develop other ways to occupy the animals to prevent negative behavior. In the present study, food in four different types of dispensers were tested on two walrus calves: fish in ice, fish in a nine‐hole container, fish in a two‐hole container, and fish in ice in a one‐hole container. All four methods of offering fish had an effect on the animals' behavior. There were differences in the way the two animals responded to each of the four dispensers. The dispensers occupied one animal on average between 32–95% of the 90‐min test periods, and the other animal for between 14–57% of the test periods. Due to the effect of learning and rapid development of the calves, which were shifting from a 100% formula diet to a 100% fish diet during the study period, the four methods cannot be compared. Besides the time feeding methods o...
Marine Mammal Science, 2000
In an attempt to test the effectiveness of sounds in deterring harbor porpoises from nets and red... more In an attempt to test the effectiveness of sounds in deterring harbor porpoises from nets and reducing porpoise bycatch in gill net fisheries, two harbor porpoises, kept in a large floating pen at Neeltje Jans, The Netherlands, were subjected to 3 different underwater sounds. The effect of each sound was judged by comparing the animals' behavior during a 15‐min test period with that during a 15‐min baseline period immediately before the test and a 15‐min recovery period immediately after the test. The effects of the alarms were quantified as the distance between the porpoises' surfacings and the alarm and the animals' respiration rates. Each alarm was tested in two positions in the pen. The behavior observed was related to the sound‐pressure‐level distribution in the pen. All three alarms: the standard Dukane alarm (a commercially available alarm with a regular pulse interval of 4.3 sec used to deter dolphins from fishing nets), the random Dukane alarm (the same alarm wi...
Marine Environmental Research, 2008
Two harbor porpoises in a floating pen were subjected to five pure tone underwater signals of 70 ... more Two harbor porpoises in a floating pen were subjected to five pure tone underwater signals of 70 or 120 kHz with different signal durations, amplitudes and duty cycles (% of time sound is produced). Some signals were continuous, others were intermittent (duty cycles varied between 8-100 %). The effect of each signal was judged by comparing the animals' surfacing locations and number of surfacings (i.e. number of respirations) during test periods with those during baseline periods. In all cases, both porpoises moved away from the sound source, but the effect of the signals on respiration rates was negligible. Pulsed 70 kHz signals with a Source Level (SL) of 137 dB had a similar effect to a continuous 70 kHz signal with a SL of 148 dB (re 1 Pa, rms). However, a pulsed 70 kHz signal with a SL of 147 dB had a much stronger deterring effect than a continuous 70 kHz signal with a similar SL. For pulsed 70 kHz signals (2 s pulse duration, 4 s pulse interval, SL 147 dB re 1 Pa, rms), the avoidance threshold Sound Pressure Level (SPL), in the context of the present study, was estimated to be around 130 dB (re 1µPa, rms) for porpoise 064 and around 124 dB (re 1µPa, rms) for porpoise 047. This study shows that ultrasonic pingers (70 kHz) can deter harbor porpoises. Such ultrasonic pingers have the advantage that they do not have a "dinner bell" effect on pinnipeds, and probably have no, or less, effect on other marine fauna, which are often sensitive to low frequency sounds.
Marine Environmental Research, 2007
Worldwide many cetaceans drown incidentally in fishing nets. To reduce the unwanted bycatch in gi... more Worldwide many cetaceans drown incidentally in fishing nets. To reduce the unwanted bycatch in gillnets, pingers (acoustic alarms) have been developed that are attached to the nets. In the European Union, pingers will be made compulsory in some areas in 2005 and in others in 2007. However, pingers may effect non-target marine fauna such as fish. Therefore in this study, the effects of seven presently commercially-available pingers on the behaviour of five North Sea fish species in a large tank were quantified. The species tested were: sea bass (Dicentrarchus labrax), pout (Trisopterus luscus), thicklip mullet (Chelon labrosus), herring (Clupea harengus), and cod (Gadus morhua). The fish were housed as single-species schools of 9-13 individuals in a tank. The behaviour of fish in quiet periods was compared with their behaviour during periods with active pingers. The results varied both between pingers and between fish species. Sea bass decreased their speed in response to one pinger and swam closer to the surface in response to another. Thicklip mullet swam closer to the bottom in response to two pingers and increased their swimming speed in response to one pinger. Herring swam faster in response to one pinger, and pout and cod (close relatives) showed no behavioural responses to any of the pingers. Of the seven pingers tested, four elicited responses in at least one fish species, and three elicited no responses. Whether similar responses would be elicited in these fish species in the wild, and if so, whether such responses would influence the catch rate of fisheries, cannot be derived from the results of this study. However, the results indicate the need for field studies with pingers and fish. Based on the small number of fish species tested, the present study suggests that the higher the frequency of a pinger, the less likely it is to affect the behaviour of marine fish.
Marine Environmental Research, 2008
Mammal Review, 2006
Accurate and sensitive survey and monitoring methods are needed for shrews. We present a new desi... more Accurate and sensitive survey and monitoring methods are needed for shrews. We present a new design of hair tube and a new, simple method of species identification from multivariate analysis of four parameters measured from shrew guard hairs using a binocular microscope with incident light. Multivariate analysis of these parameters measured from hairs of known identity showed that they can be used to identify hair to the species level with 85% accuracy. We compared our indices of abundance from hair tubes (the hair tube index) with those from live trapping in 40 field margins. Capture‐mark‐recapture methods showed that capture rate did not vary systematically across sites, so that number of individuals captured was used as an index of abundance. The hair tube index showed a significant association with the number of individuals captured for Sorex araneus and Neomys fodiens. The lack of a significant association for Sorex minutus may be because hair tubes are more sensitive in detect...
The Journal of the Acoustical Society of America, 2008
Echolocation effort (number and duration of echolocation click trains produced) by a harbor porpo... more Echolocation effort (number and duration of echolocation click trains produced) by a harbor porpoise is described in relation to target presence, strength and distance, and performance of the detection task. The porpoise was presented with two target sizes at five distances (12–20m), or no target, and had to indicate whether it could detect the target. Small, distant targets required long and multiple click trains. Multiple click trains mostly occurred when the small target was far away and not detected, and during target-absent trials in which the animal correctly responded. In target-absent trials, an incorrect response was linked to short click trains. Click train duration probably increased until the animal’s certainty about the target’s presence or absence exceeded a certain level, after which the porpoise responded.