Which Beak Fits the Bill? - An Activity Examining Adaptation, Natural Selection and Evolution

Oct 15, 2026

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Evolution is a unifying concept within biology, yet many students hold misconceptions about how evolution works. This activity uses bird beaks as tools to model adaptation and natural selection by having students forage for different seed types, collect data, and interpret variation in feeding traits. The inquiry extends to hypothesizing population changes when seed abundances shift and comparing results with observed patterns from Darwin’s finches.

LanguageEnglish

CategoryExam

FormatPDF

Pages3

Reading Time8 min

AccessFree to download

Abstract

Introduction

Methods

Activity One: Foraging in an environment with equal quantities of four different sized seeds

Data collection and Table 1 setup

Student questions

INNOVATIONS Which Beak Fits the Bill? An Activity Examining Adaptation, Natural Selection and Evolution Randi (Ruth) Darling Biology Department, Westfield State University, 577 Western Ave, Westfield, MA 01086 [rdarling@westfield.ma.edu](rdarling@westfield.ma.edu) Abstract: Evolution is a unifying concept within biology. In fact, Dobzhansky, a noted evolutionary biologist, argued, "Nothing in biology makes sense except in the light of evolution" (Dobzhansky, 1973) . However, often students have misconceptions about evolution. There are a number of available activities where students use tools (representing bird beaks) to collect different food items. These activities enable students to see how various beaks are adapted to feeding on certain types of food. This article describes an inquiry-based activity that takes the process several steps further. In this inquiry-based activity, students not only examine adaptations that birds have for capturing prey, and changes in a bird population over time, but also hypothesize what would happen to the bird population if relative seed abundances change over time. Students then model an environmental change recorded by researchers when observing Darwin’s Finches. The Grant’s observed a severe drought in 1977 resulting in a drastic decline in seed production with small seeds being particularly affected (Grant, 1999; Boag & Grant 1981) . Students then test their hypothesis and compare their findings to those observed by the Grants. This activity is well suited for students in general biology, ecology or evolution classes. Key words: Evolution, natural selection, adaptation, variation in populations INTRODUCTION Organisms display variation in traits such as body size, color, speed, and aggressiveness. Variation is found between species and within a species. Many traits of organisms are adaptations to their environment. In birds, for example, there is variability in the size and shape of the beak, or bill, which is utilized for finding and capturing food. Some birds have wide, thick bills used for crushing seeds; some have short, thin bills for picking up small prey; while others have long tubular bills for drinking nectar from flowers. The adaptations that we see in organisms are a result of evolution by natural selection. Before conducting this activity, I introduce the concepts of adaptation, natural selection and evolution. In class, we discuss variation in bill shape and size in Darwin’s finches, and how this variability arose. Then, after discussing evolution by natural selection, the students conduct this inquiry-based activity allowing them to simulate evolution. METHODS I divide the class into groups of 5-6 students per group. In each group, one student serves as the timer, and data recorder for the group (students can alternate jobs for Activity 2) . The remaining students are “birds” and forage for seeds. Students use tweezers, pliers and other household items to simulate variation in bird beaks within a population of birds feeding on a variety of types of seeds. The “birds” each select one of five different beaks, such that in each group there are five different types of birds. I provide a range of beaks sizes to choose from. Ideas for beaks include: pointed tweezers, wide tweezers, eyelash curlers, needle nose pliers, regular pliers, forceps, snap clothespins, and different sizes of binder clips. When choosing beak types, choose a range of types including some that are very pointed, and others that are wider. This activity works best if all the pliers are spring loaded. Each student uses their beak to forage for seeds. I explain that each student simulates a bird’s beak. Students represent birds with variability in beak size and shape within a single species (for example, within one species of Darwin’s finches) . First, students gain experience using their beak. I have each group assemble four stations, one for every seed type: thistle, safflower, black

FAQs

What is the purpose of the beak-foraging activity?

The activity helps students examine how beak structure relates to adaptation and feeding, and how natural selection can lead to changes in bird populations over time.

How do students collect data during the activity?

Students use beak tools to forage at stations containing different seed types for one minute, count seeds captured, and record results in Table 1.

What hypothesis do students test in Activity One?

In an environment with equal quantities of four seed types, students predict which beak types would become most abundant and which would be least common, based on how well each beak captures different foods.

Oct 15, 2026

Upload by Ben