Defra - Department for Environment, Food and Rural Affairs.

Science Search

Science and Research Projects

Return to Science Search homepage   Return to Project List

Improved estimates of daily food and water requirements for use in risk assessments - PS2330

Description
Methods of estimating water intake in birds for risk assessment were reviewed in project PS2327. Current methods of estimating the drinking water requirements of birds were considered to be unsatisfactory as they do not take account of the water in the food so that a bird eating dry seeds would appear to have the same drinking water requirements as a bird feeding on leaves. It was recommended that drinking water estimates should be based on estimates of water influx rate (WIR) from doubly labelled water (DLW) studies combined with estimates of water in food and metabolic water production to calculate drinking water requirements. This provides a more realistic estimate of drinking water requirements than the existing method and is similar to the approach used for estimating daily energy expenditure (DEE) and food requirements in project PN0908.

It was recommended that where WIR estimates from studies on the species of concern are available, these should preferably be used in any risk assessment. Where WIR estimates for the species of concern are not available (which is the case for most UK species), estimates should be based on the appropriate allometric equation from Nagy and Peterson (1988), which allow predictions to be made for birds of different sizes and types (passerines, carnivores etc.). However, given the relative lack of actual measured WIR values for UK species, and the large number of DLW studies conducted since the late eighties when the existing allometric equations for water flux were developed, it was also recommended that these are updated to include this new information.

Given the need to review the DLW literature to update the water intake estimates, and the ongoing revision of the current SANCO bird and mammal risk assessment guidance document, then it would be sensible to gather recent information about energy requirements at the same time so that these estimates can also be updated. This would ensure that the new guidance is based on the most up to date information available. These data can be incorporated, where appropriate, into the WEBFRAM models of pesticide risk assessment published on the internet in which external users can carry out probabilistic assessments of the effects pesticides on wildlife.

Also, as part of PN0908, it was shown that the relationship between avian body mass and energy expenditure within a species was often quite different from that between species: a fat blue tit may not use the same energy as a thin great tit. It would be helpful to check for similar relationships among mammal species. And because risk analyses are usually focused at the level of the individual bird or mammal, it is appropriate, especially for probabilistic assessments, to collect information on individual variation in energy expenditure.

The aims of the project are to:

Provide improved methods of estimating daily water intake by birds for use in risk assessments by including data from DLW studies conducted since the publication of Nagy and Peterson (1988).

Update the existing estimates of energy and food requirements of birds and mammals by including data from DLW studies conducted since the completion of PN0908.

Investigate the relationship between bodyweight and measured energy expenditure within species for mammals.

Present the above information to PSD in a form that can be of immediate use in risk assessments.

Literature from DLW studies will be reviewed to develop an up to date database of energy and water requirements for birds. Recent data on energy requirements of mammals will also be collated. These will then be used to generate allometric equations like those of Nagy and Peterson (1988) for water intake and Crocker et al. (2002) for energy requirements.
Objective
Provide improved methods of estimating daily water intake by birds for use in risk assessments by including data from doubly-labelled water (DLW) studies conducted since the publication of Nagy and Peterson (1988).
2. Update the existing estimates of energy and food requirements of birds and mammals by including data from DLW studies conducted since PN0908.
3. Investigate the relationship between bodyweight and measured energy expenditure within species for mammals.
4. Present the above information to PSD in a form that can be of immediate use in risk assessments (e.g. spreadsheets, tables etc.) as was done in project PN0908.

Project Documents
• Final Report : Improved estimates of daily food and water requirements for use in risk assessments   (523k)
Time-Scale and Cost
From: 2007

To: 2007

Cost: £17,331
Contractor / Funded Organisations
Central Science Laboratory
Keywords
Agriculture and Food Chain              
Birds              
Crops              
Drinking Water              
Environmental Effects              
Habitats              
Indicators              
Mammals              
Pest and Weed Control              
Pesticide Residues              
Pesticide use              
Pesticides              
Plants and Animals              
Risk assessment and management              
Water              
Fields of Study
Pesticide Safety